A COMPARISON OF TWO PLATE WASTE EVALUATION

METHODS IN PUBLIC SCHOOLS

by

KATHERINE NOTZON ANDERSON, B.S.

A THESIS

IN

RESTAURANT, HOTEL, AND INSTITUTIONAL MANAGEMENT

Submitted to the Graduate Faculty of Texas Tech University in

Partial Fulfillment of the Requirements for

the Degree of

MASTER OF SCIENCE

Approved

Accepted

August, 1994

~0 .s ~3 11'1~4 tJ (). i ~r'

ACKNOWLEDGEMENTS

I would like to thank the members of my thesis

committee, Dr. Hoover, Dr. Huffman, and Dr. Martin. They

all aided in my achievement of this goal, which at times,

felt quite elusive. A most special thanks must go to my

committee chairperson, Dr. Hoover. She spent a considerable

amount of time and effort helping me to get this thesis into

a publishable form.

For the love, support, prayers, and encouragement, I

would like to thank my entire family but especially my

parents, Frederic and Estela Notzon. Their support always

kept me going. A most special thanks must also go to my

beloved late husband, Conde Nevin Anderson, III.

Remembering both his encouragement and continuous belief 1n

me made this dream a reality.

TABLE OF CONTENTS

ACKNOWLEDGEMENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

L I S T 0 F TAB L E S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

CHAPTER

I. INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Statement of the Problem...................... 2

Purpose of the Study.......................... 3

Hypotheses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Definitions................................... 3

Research Assumptions.......................... 4

Research Limitations.......................... 5

II. REVIEW OF LITERATURE.......................... 6

History of School Food Service and Governmental Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Dietary Guidelines. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Nutrition Education and Training.............. 10

Plate Waste................................... 11

Plate Waste Methods........................... 12

Time Studies.................................. 15

Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

I I I . METHODOLOGY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Site.......................................... 17

Sub j e c t s • . • • . . • . • . . . . . • • . . . . . . . . . . . . . . • . . . . . . • 18

Pilot Study................................... 18

Data Collection............................... 19

Variables..................................... 21

111

D at a An a 1 y s i s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

IV. RESULTS AND DISCUSSION........................ 23

Participant Demographics...................... 23

Correlation of Plate Waste Methods............ 25

Time Required to Assess Plate Waste........... 30

An a 1 y s i s o f R e s u 1 t s . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2

V. SUMMARY AND CONCLUSIONS....................... 36

Major Findings of the Study................... 37

Impact of the Study........................... 38

Recommendations for Further Research.......... 39

Conclusion.s ................................... 39

REFERENCES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

APPENDICES

A. PLATE WASTE RECORD. . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

B. BACKGROUND OF RESEARCHERS..................... 46

C. STANDARD WEIGHT RECORD........................ 47

D. VISUAL ASSESSMENT PLATE WASTE PROCEDURES ....... 48

E. SCRAPE/WEIGH PLATE WASTE PROCEDURES ............ 50

F. PLATE WASTE TIME SHEET. . . . . . . . . . . . . . . . . . . . . . . . . 52

lV

LIST OF TABLES

1. Profile of students by gender, grade and ethnic i t y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 4

2. Correlation of accuracy based on menu item.............................................. 26

3 . Comparison of correlations with prior plate waste studies .............................. . 28

4. Mean time required per tray to assess plate waste based on observation method ...................... . 31

5 . Mean time required per tray to assess plate waste based on type of tray ............................ . 33

v

CHAPTER I

INTRODUCTION

School food service personnel have the responsibility

of adequately feeding the nation's school-aged children

according to guidelines set forth by the United States

Department of Agriculture (USDA). School lunches served, as

specified by the National School Lunch Program (NSLP), must

account for one-third of the children's required daily

intake (Public Law 79-396). Although the majority of the

school meals offered should be consumed by the children,

plate waste is a serious problem that plagues the school

food service industry.

The National School Lunch Act of 1946 (Public Law 79-

396) and the Child Nutrition Act of 1966 (Public Law 89-642)

authorized the federal financing of food assistance to

approximately 28 million children through nine various

programs which are all classified as child nutrition

programs ("Chapter IV: Child Nutrition Programs," 1989).

The USDA subsidizes school food service operations only for

meals which follow the meal patterns and serving sizes

specified by the Child Nutrition Program. Although simply

offering the appropriate meal patterns in the mandated

amounts keeps the school food service operations in

compliance and in business, the reason for the existence of

the food service programs must not be overlooked. The focus

1

of a school food serv1ce operation should be to offer

nutritious and appealing food which contributes to the

health and well-being of children. This goal cannot be

accomplished if food is not consumed by the children,

resulting in large amounts of waste.

Statement of the Problem

Plate waste is measured for various reasons. Food

service personnel measure plate waste to determine the

popularity of given menu items, especially when trying out

new products or when serving traditional menu items that

have been prepared with revised recipes. Educators look at

plate waste when determining the effectiveness of nutrition

education curriculum. Effective curriculum not only

1ncreases nutrition knowledge, but also, can cause a

positive change in eating behavior. This change would be

noted by the decreased amount of food the children discard

on their trays (Graves & Shannon, 1983). Parents and

taxpayers, although not actively involved in studying plate

waste, need to be aware of the problem. It costs both

groups 1n the monetary sense, and for parents, the loss of

nutrition for their children. Keeping in mind resources

such as time, money, and effort, identifying accurate and

efficient methods for determining plate waste is necessary

both from a research, and an economic point of view.

2

Purpose of the Study

The purpose of the study was to compare the visual

assessment method and the scrape/weigh method for

determining plate waste. Specific objectives of the study

were to:

1. Measure plate waste utilizing the visual method

and the scrape/weigh method.

2. Compare the accuracy of the visual assessment

method with the scrape/weigh method.

3. Compare the time required for data collection for

each method.

Hypotheses

This study incorporated the following null hypotheses:

1. The correlation for accuracy is low between the

visual assessment and the scrape/weigh method when

determining plate waste.

2. There is no significant difference 1n the time

required for data collection for the two methods.

Definitions

A contract management company 1s a company which runs

the food service operation of a third party by providing a

management team, policies and procedures, and other

operational provisions in exchange for a management fee.

3

Plate waste constitutes any food which is left uneaten

4

on a tray with the intention that it be thrown away (Spears,

1990).

The scrape/weigh method involves scrap1ng the edible

portions of food left on a tray, onto a pre-weighed

container, placing this container onto a scale and recording

the weight (Spears, 1990).

Type A school lunch refers to the lunch served in a

school cafeteria which meets the USDA criteria for meal

pattern and serving sizes. It is also referred to as a

reimbursable lunch (Pannell, 1990).

The visual assessment method is used in determining

plate waste by visually estimating food left on a tray and

recording observations by means of predetermined coding

(Spears, 1990).

Research Assumptions

The first assumption in this study was that the

individuals who observed and recorded plate waste possessed

the skills necessary to collect accurate data. With the

scrape/weigh method, a digital scale was used to determine

an objective measure of plate waste. Therefore, the next

assumption was that the scrape/weigh method yielded an

accurate measure.

Method bias was controlled by: (1) the order of data

collection (visual assessment was performed before the

scrape/weigh method so that the researchers were not either

5

consciously nor unconsciously trying to match the known

plate waste); (2) the design of the data collection forms

(results for each method were recorded on separate pages, to

avoid the opportunity to match data); and (3) limiting the

communication during assessments strictly to verbalizing

plate waste measurements and indicating when to start and

stop timing (to avoid possible cuing).

Research Limitations

The most substantial limitation in this study is that

of human error. Although all effort was made to ensure

accuracy of results, findings may not be 100% accurate.

Another possible limitation of this research is that the

findings cannot be generalized to other sites and types of

food service operations.

CHAPTER II

REVIEW OF LITERATURE

History of School Food Service and Governmental Support

The practice of serving food at school had its

beginnings as early as 1853 and was accomplished primarily

through volunteer groups. It was not long before schools

across the country took on the responsibility of serving

lunches. However, school lunch (program) expansion was not

seen until the Great Depression of the 1930s. It was at

this time that modest efforts by the federal government to

assist school lunch programs were initiated (Pannell, 1990).

Federal support of the school lunch program was

provided initially by relief programs. Relief included

employment within the school lunch program, and also, the

donation of surplus commodities. From the perspective of

the federal government, the school lunch program served two

basic purposes: to offer employment (at a time when this

country had under 25% of its workforce unemployed), and to

help farmers unload their price depressing agricultural

surpluses ("Chapter IV: Child Nutrition Programs," 1989).

As the growing awareness of the relationship between

nutrition, good health, and learning was becoming more

apparent, Congress approved the National School Lunch Act on

June 4th, 1946 (Public Law 79-396). Its intent was to

provide a basic level of support for all school children

6

both nutritionally and financially ("Chapter IV: Child

Nutrition Programs," 1989).

7

As early as the 1960s, legislators and other

policymakers began to focus on America's hunger and poverty.

This interest led to the passing of the Child Nutrition Act

of 1966 (Public Law 89-642). The Act provided for the first

substantial funding for needy children's meals, developed

guidelines for identification of the needy, and provided the

basis to pilot a breakfast program (Pannell, 1990).

Pressures mounted based on the growing number of

schools operating lunch programs, increased concern about

balanced diets, good nutrition, and the changing economy.

Due to these pressures, the USDA came to the realization

that commodities alone did not provide adequate support for

school lunch programs. Therefore, increased financial aid

would be necessary. After 1970, federal cash assistance

finally exceeded commodity aid to child nutrition programs.

Through the years, cash aid for child nutrition programs has

increased. For fiscal year ending in 1993, preliminary data

indicated cash assistance for the National School Lunch

Program (NSLP) topped $4 billion for the first time

(Hiemstra, 1994). School Breakfast, although a considerably

smaller program, received $868 million in 1993, an 1ncrease

of 10% (Hiemstra, 1994). The financial assistance for both

the breakfast and lunch child nutrition programs represents

participation of 29,400,000 children (United States

Department of Commerce, 1993).

Dietary Guidelines

8

To g1ve additional support to the NSLP, the USDA worked

1n conjuction with the United States Department of Health

and Human Services (DHHS) to issue the Dietary Guidelines

for Americans (USDA & DHHS, 1990). This pamphlet has been

used as a nutrition education tool for the public and

school-aged children (DeMicco, 1990). The USDA highly

recommended that school districts use the Dietary Guidelines

for Americans (DGA) in planning the breakfast and lunch

menus.

In order to assist in meeting DGA objectives, the USDA

developed new recipes, as well as modified pre-existing

government issued recipes, for use in school kitchens across

the nation. The recipes were lower in salt, fat, and sugar

(Glover, Stitt, Kendrick, & Hayes, 1991). However, s1nce

plate waste and participation have been problems in the

past, some food service managers and directors were

concerned about using the new rec1pes. They questioned

whether the new recipes would result in students being even

less likely to eat foods with reduced fats, salt, and sugar.

Many food service managers and directors were fearful that

plate waste would increase while participation would

decrease. Investigators have, however, reported that

9

reduced fat and sodium foods are acceptable to school-aged

children (Coale & Bedford, 1984; Sandoval, Lockner, &

Adkins, 1986). However, preference for higher fat foods was

evident.

To implement the DGA, it is important to first identify

possible barriers and to address them. Barriers likely to

be faced by school food personnel are: lack of awareness or

knowledge regarding the DGA; apathy toward using DGA; and

non-support by school administrators, teachers, and parents.

Additional barriers are: fear of risks associated with

trying new menu items such as student rejection of foods or

financial risk; lack of culinary, nutrition, or food science

skills in developing, modifying, or preparing appropriate

recipes; and contraints imposed by the operation such as

kitchen equipment (DeMicco, 1990).

To eliminate the barriers for implementing DGA, Glover

et al. (1991) indicated that cafeteria managers needed

assistance. This assistance should come in the form of

increasing the availability of ingredients and food items

that make it possible for them to plan and prepare meals

that follow DGA.

DeMicco (1990) offered many strategies to help

implement DGA. Strategies included: (1) gaining support

from administrators, school food service staff, teachers,

and parents; (2) developing educational programs for

elementary school teachers in order for them to teach

10

students about the DGAs; (3) developing training programs

for food service personnel on the DGA; and (4) continuing to

work on developing and modifying recipes to reflect DGA.

Nutrition Education and Training

As the links between eating and learning, health and

well-being are being recognized, nutrition education has

gained importance in the schools. The intent of legislation

in establishing nutrition education programs such as

Nutrition, Education, and Training (NET), is to "teach

children through a positive daily lunchroom experience and

appropriate classroom reinforcement, the value of a

nutritionally balanced diet" (Maretzkik, 1979, p. 176).

Until recently, most nutrition education programs have

emphasized learning to choose from the four basic food

groups and, presumably, this knowledge would assure adequate

nutrient intake. Although such programs do increase

nutrition knowledge when students are subsequently tested, a

corresponding improvement in student food behavior is often

lacking (Green & Munroe, 1987; Contento, Manning, & Shannon,

1992).

Many nutrition education programs are currently

available and utilized. Most of these programs share some

basic characteristics. They are designed primarily to: (1)

encourage positive eating habits through alternative menus;

(2) promote nutrition education in the classroom; and (3)

11

train teachers and food service personnel to carry out these

goals {Contento, Manning, & Shannon, 1992; Sandoval,

Lockner, & Adkins, 1986). Regardless of the curriculum

implemented, a means of program assessment is necessary.

One of the most valid assessments of any nutrition

education program 1s through monitoring student plate

waste/consumption data. Therefore, plate waste evaluations

should be an integral part of any nutrition education

program {Green & Munroe, 1987).

Plate Waste

In any non-commercial food service program, one would

expect to observe some degree of plate waste (Lilly, Davis,

Wilkening, & Shank 1980). Many factors contribute to this

problem in the school setting: scheduling recess either

before or immediately after the lunch period (Read &

Moosburne, 1985; Schwab, 1989); serving too large a portion

of food; differences in food preferences {Lachance, 1976;

Jansen & Harper, 1978); lack of nutrition educat1on (Kirks &

Wolff, 1985; Graves & Shannon, 1983); and lack of food

quality due to poor preparation techniques (Devan, Gregoire,

& Spears, 1988).

The need to curb plate waste is vitally important for

two basic reasons, the first being cost. In 1987, it was

estimated that $600 m1llion was spent in the US on plate

waste (Green & Munroe, 1987). Secondly, and even more

12

critical than the monetary issue is the loss of nutrients to

the school children. Although most Type A school lunches

achieve the standard for many nutrients, some noon meals

will fall below the desired level of nutrients when all of

the food served is not eaten (Lilly et al., 1980).

Recent research has indicated that most adult heart

disease begins in childhood. Therefore, not only how much

children eat, but what children eat will have an impact on

their health as adults ("Project 2001," 1991).

Plate Waste Methods

Three generally accepted methods for determining plate

waste are: self-report, scrape/weigh, and visual

assessment. Of the three methods, self-reporting 1s the

least utilized. Although the self-report method has been

shown to produce similar results when compared to

scrape/weigh and visual assessment methods, scrape/weigh and

visual assessment are most highly correlated (Comstock, St.

Pierre, & Mackiernan, 1981; Holdt, Sitter, & Gates, 1993).

Comstock, St. Pierre, and Mackiernan (1981) documented

correlations of .93 when compar1ng scrape/weigh and visual

assessment, and .74 when compar1ng scrape/weigh and self­

report. A study by Holdt, Sitter, and Gates (1993) which

also compared the scrape/weigh to visual assessment and the

scrape/weigh to self-report produced correlation

coefficients of .92 and .78, respectively. In addit1on to

the differences in correlations, an added concern is the

potential for errors in self-reported dietary intake data

(Dubois, 1990).

13

Scraping and weighing edible portions of plate waste is

the most traditional method and thought to be most accurate

(Comstock, St. Pierre, & Mackiernan, 1981). This method

does have inherent weaknesses. It 1s messy, time-consuming,

and requires adequate staffing and space (Comstock, St.

Pierre, & Mackiernan, 1981). The visual assessment method

has positive aspects for food service personnel who may

continue plate waste observations in the future. Advantages

of visually assessing plate waste includes the modest time

required, simple equipment (paper and pencil) needed, and

the amount of data that can be obtained in a short time

(Lachance, 1976).

Because of the visual assessment method's s1mplicity,

it would appear to be the method of choice for most

researchers. The scrape/weigh method and the visual

assessment method have been compared to determine the

similarity of results. In a study conducted by Lachance

(1976), it was found that as long as the visual method was

perfomed in a very systematic manner, the method yielded

reliable data. Data gathered from 85 trays showed total

plate waste amounts of 41.2% for the visual est1mation

method, and 43.3% for scraping and weighing, a difference of

only 2.1%. Likewise, Comstock, St. Pierre, and Mack1ernan

(1981) found that by us1ng trained data collectors, visual

estimations of plate waste correlated highly with actual

plate waste (approximately .93).

14

On the other hand, the research by Kirks and Wolff

(1985) resulted in a different conclusion. They contended

that previous plate waste studies showing high correlat1ons

amongst the two methods were not totally valid because

visual assessment was tested using an insensitive

instrument.

In these earlier studies, the two plate waste methods

were correlated without pretest/posttest evaluations and

also, without treatment versus control groups. Kirks and

Wolff (1985) found that the visual assessment method had

high correlations to the actual weights, but that the

validity of the visual assessment method was inconsistent.

When looking at total amounts of plate waste, the

discrepancy was statistically significant. In their study,

visual estimation showed a total of 3% decrease in plate

waste after nutrition education, while the actual weight

showed plate waste was lowered by 32%. If one were to use

visual estimates exclusively, one might conclude that the

nutrition education curriculum had not been successful in

changing the children•s food behavior; the scrape/weigh

method showed the reverse to be true.

15

Time Studies

Previous researchers have indicated that in using

either the scrape/weigh or the visual assessment method, a

time difference exists between using the two. To determine

if the scrape/weigh method is a more time consuming

procedure as compared to the visual assessment method, a

time study must be conducted. The direct time study

approach, often called a time study, a stopwatch study, or

clocking the job, is the most widely used method for

establishing work standards (Adam & Ebert, 1989).

Work measurement, another term which can be used

interchangeably with time study, is defined as a method of

establishing an equitable relationship between the amount of

work performed and the human input used to do that work.

Time studies or work measurement are necessary to determine

if human resources are being effectively used (Spears,

1990).

The importance of timing is that standard time data are

established, and reasonable estimates of cost for utilizing

a given method may be determined. Timing is helpful in that

one can use the information to better schedule and staff for

the method chosen, and overall, timing allows one to

effectively evaluate alternatives (Konz, 1990).

Summary

There is a concern amongst parents, taxpayers, school

food serv1ce personnel, educators, and the federal

government. This concern centers on whether children are

receiving and consuming nutritious meals while at school.

School food service personnel strive to serve nutritious

meals, and educators, strive to improve the nutrition

knowledge and eating behaviors of the children.

Assessing whether children are consuming the meals

offered at school can be determined through plate waste

analysis. The plate waste method chosen should be

effective, accurate, and efficiently utilize resources.

16

CHAPTER III

METHODOLOGY

The purpose of this study was to determine the degree

of correlation for accuracy existing between the

scrape/weigh method and the visual assessment method for

identifying plate waste. Time requirements were calculated

for both methods to determine which plate waste method was

more efficient. Ease of use for a particular method was not

quantitatively measurable and so was not included in this

study as a dependent variable. However, this factor will be

discussed.

Site

The site chosen for data collection was an elementary

school located in west Texas, and representative of those in

the area. The food service department at this school was

operated by a contract management company. The dining room

contained seating for 240 students.

The dishroom, where plate waste measurements were made,

was a 10 x 13 1/2 foot facility. The counters were made of

stainless steel and ran the length and width of the room.

Three food carts were available for retrieving and

transporting lunch trays to the dishroom.

17

18

Subjects

The subjects from whom plate waste data were collected

included children enrolled in kindergarten through fourth

grade at an elementary school. Only children eating a lunch

provided by the school were included in this study. The

data were collected over a period of two days. The subjects

were from a random sample and were stratified based on

grade.

The number of students in the study per day was based

on 10% of the school's enrollment per grade. The current

enrollment averaged 530. The study incorporated a m1n1mum

of 50 students daily, with nine or more students per grade.

Every eighth student was counted upon exiting the lunch line

and was given a Plate Waste Record (Appendix A) at the

dining table.

Pilot Study

A pilot study was conducted to develop and refine

procedures and forms that were to be used in the actual

study. Based on results of the pilot study, m1nor rev1s1ons

were made on the Plate Waste Record. The original form did

not incorporate a means for recording demographic data. In

addition, data not considered pertinent for this study (such

as school number) was omitted from the form used for the

present study.

The subjects used in the pilot study were third and

fourth graders. In total, 72 trays were collected.

19

The visual assessment was first used to determine plate

waste. After recording visual assessment data, the Plate

Waste Record form was turned over so that the weight of the

plate waste could be recorded. The pilot test procedures

used to measure plate waste for both methods were effective

and were utilized for the present study.

Data Collection

Data on plate waste were collected over a two day

period during the spring of 1994. Three researchers

(Appendix B) collected the data. One researcher assessed

the plate waste by the visual assessment method and by the

scrape/weigh method. The second researcher recorded the

data, and the third researcher took the timings for both

methods and recorded the timings. A training sess1on for

the researchers was held prior to collecting data for the

study. Additionally, the researchers spent one day on site,

practicing the procedures and protocol which were to be used

1n the actual study.

The Standard Weight Form (Appendix C), which was

designed to provide a record of the average weight for all

menu items, was filled out prior to the beginning of meal

service. To accomplish this, five trays were purchased and

taken to the dishroom where each menu item was scraped and

20

weighed. Using the five weight scores per item, an average

was computed for each menu item resulting in standard

weights.

Forms, which had been customized and preprinted based

on the menu, were checked against the food on the serving

line. Any menu substitutions, additions or deletions were

noted and the forms modified. Forms were sequentially

numbered prior to arriving at the site.

Four of the five trays which were purchased to obtain

standard weights, were altered to resemble the various

stages of plate waste using the visual assessment scale:

(1) majority of food consumed; (2) 50% consumed; (3) 1 bite

to 25% consumed; and (4) none consumed. The altered trays

were used as a visual standard for the researcher during

actual plate waste assessment.

After the dishroom was set up and all forms were

prepared, the researchers went into the cafeteria area to

select the subjects. The researchers were stationed at the

end of the cafeteria line. Two of the researchers counted

off the appropriate number of children, followed the

children to their tables to record the necessary information

(a legend was attached to the researchers' clipboards which

revealed the meaning of demographic codes), and proceeded as

outlined in Appendices D and E. The third researcher

collected the trays and forms as the children finished

lunch, set them up in the dishroom according to grade, and

21

discarded any disposable items (i.e., plastic forks, spoons,

napkins) which would not be used for either method of plate

waste analysis.

Plate waste procedures for the visual assessment method

(Appendix D) were used to guide researchers. Research

procedures required the timing of the visual assessment

method to begin when each tray was ready to be assessed, and

to stop after each of the trays had been assessed. Appendix

E was used to guide researchers through the plate waste

procedures using the scrape/weigh method. Research

procedures required that the timing for each tray assessed

by the scrape/weigh method begin as soon as food was

prepared for weighing and to stop timing after all menu

items on the tray were weighed. Timings for the two methods

were recorded on the Plate Waste Time Sheet (Appendix F).

Variables

The independent variable in this study was the method

used to determine plate waste. The dependent variables were

the accuracy of the results and the time involved in

measuring plate waste.

Data Analysis

Analysis included descriptive statistics for the

demographic data. To determine the degree to which a

relationship existed between the two methods of plate waste,

correlations were calculated us1ng Pearson r. Analysis

included the correlations for specific menu items, and

overall for meals.

22

To ascertain if there was a difference in the time

required for data collection for the two methods, the t-test

for nonindependent samples was used. The alpha level was

considered significant at .05.

CHAPTER IV

RESULTS AND DISCUSSION

This study compared two plate waste evaluation methods,

scrape/weigh and visual assessment. Both methods were

utilized to measure plate waste at an elementary school

cafeteria in west Texas. The degree to which the plate

waste results correlated was determined, as well as the time

that was required to assess each tray by method. The data

for this study were collected over two nonconsecutive days,

during the months of April and May of 1994.

Participant Demographics

Table 1 shows the demographic profile of those who

participated in this study. Kindergarten through fourth

grade students were included. Each grade was represented

relatively evenly, although observations of first graders

was slightly higher due to a larger enrollment of this

grade.

There were 54 subjects on the first day of the study,

50 subjects on the second day, resulting in 104 total

observations. The ratio of males to females in this study

was evenly divided. However, this factor occurred by chance

and was not manipulated by the researcher. The students

were predominantly White (64%), followed by Hispanic (28%).

23

Table 1: Profile of students by gender, grade and ethnici ty. a

Characteristic Number

Gender

Female 50

Male 49

Data unavailable 5

Grade

Kindergarten 18

Grade 1 24

Grade 2 19

Grade 3 19

Grade 4 20

Data unavailable 4

Ethnicity

African American 2

American Indian 0

Asian 0

Hispanic 29

White 67

Data unavailable 6

24

Percent

48.1

47.1

4.8

17.3

23.1

18.3

18.3

19.2

4.8

1.9

0.0

0.0

27.9

64.4

5.8

25

Correlation of Plate Waste Methods

Plate waste data for the scrape/weigh and the visual

assessment method were collected according to the procedures

outlined in Appendices D and E. From the data, a

correlation coefficient for the two methods, based on menu

items, was computed (Table 2).

The correlation coefficients 1n this study ranged from

.81 to .99. Overall coefficients for day one and day two

equalled .86 and .85, respectively.

The data that were gathered to acquire correlations

between the two methods of plate waste were analyzed

further. The objective was to determine if the type of menu

item affected the accuracy of the visual assessment method

in comparison to the scrape/weigh.

Table 2 shows the results of menu item analysis. Of

the 12 menu items served, three were repeated on both days.

These repeated items included mashed potatoes, dinner rolls,

and milk. All three items closely correlated: mashed

potatoes .93 and .95; dinner rolls, .97 and .95; and for

milk, .93 and .92.

The main entree on day one was oven-fried chicken and

consisted of chicken nuggets on day two. It was in the meat

category where both the highest and the lowest correlations

for the entire study were found. As was expected, chicken

nuggets proved to have a considerably higher correlation

than the oven-fried chicken, with correlation coeffic1ents

26

Table 2: Correlation of accuracy based on menu item.

Day 1 Day 2

Corre- Corre-lation Number lation Number Coeff- of Coeff- of

Menu Item icient Servings icient Servings

Meat/Meat Alternate

Oven-fried chicken .81 54

Chicken nuggets .99 49

Vegetable/Fruit

Mashed Potatoes .93 52 .95 49

Green Beans .97 35

Spring Peas .95 31

Mixed Fruit .96 41

Bread/Bread Alternate

Dinner Roll .97 54 .95 50

Milk

Milk .93 53 .92 48

Other

Cake .94 51

Overall .86 54 .85 50

27

of .99 and .81, respectively. To visually assess the oven­

fried chicken, the researcher had the chicken bone to

contend with, making it difficult to estimate how much of

the meat was actually left. The chicken nuggets, however,

were totally edible. In addition, all students were served

four chicken nuggets. This portion based on count made

estimation extremely easy, because the numbering of the

visual assessment scale coincided exactly with the number of

nuggets. For example, 1n the visual assessment method, four

signifies that no food 1s consumed. Therefore, if the four

nuggets that were served were still left on the tray, the

researcher knew that none had been consumed and assigned a

four.

Menu items in the remaining components varied only

slightly in their correlations. Within the vegetable/fruit

component, coefficients for the five items ranged from .93

to .97. In the other component, which consisted of a slice

of cake, correlations were .94. All correlations in the

study were quite high.

Previous studies conducted to determine a correlation

between the scrape/weigh and visual assessment method

provide similar findings (Table 3). For their study,

comstock, St. Pierre, and Mackiernan (1981) modified the

five-point scale recommended by Lachance (1976) into a S1X­

point scale. They then proceeded to determine if there were

correlations between the two plate waste methods. The1r

28

Table 3: Comparison of correlations with prior plate waste studies.

Study

Present Study {1994)

n = 104

Correlations

By Menu Items

Overall

Comstock, St. Pierre, and Mackiernan (1981)

n = 500 By Meal Components

Overall

Dubois {1990)

n = 283 By Meal Components

Overall

Kirks and Wolffe (1985)

n = 343 By Meal Components

Overall

Stallings and McKibben {1982)

n = 250 By Menu Item

Overall

Value Range

.81 to .99

.85 to .86

.77 to .98

.90 to .95

.90 to .98

.95

.92 to .93

.80

.58 to .99

not reported

29

study produced correlations by meal components ranging from

.77 to .98. Overall values for this study ranged from .90

to .95.

Stallings and McKibben (1982) found from their two-day

study that the visual assessment method measured plate waste

accurately when compared to the scrape/weigh. The

correlations by menu item ranged from .58 for fruit cocktail

to .99 for a dinner roll.

The correlations obtained 1n the study by Dubois (1990)

were similar to the present study, although the objectives

were different. Dubois wished to quantify the magnitude and

direction of the inaccuracy found in visual assessment when

compared to the scrape/weigh. Her correlations by meal

components ranged from .90 to .98. Kirks and Wolff (1985)

found high correlations within certain food groups,

specifically the protein and bread groups, with values of

.93 and .92. Their overall value was .80.

During the present study, some students (third and

fourth graders) were allowed to participate in the offer

versus serve program. Offer versus serve allows students to

choose everything offered to them on the serving line, or

they may choose among the components (i.e., meat and bread)

as long as a minimum of three are picked up. The three

components they choose must be acceptable based on the USDA

meal pattern guidelines. Therefore, due to offer versus

serve, not all meal components were chosen by the students

30

~n th~s study. The number of menu items served during the

two day period reflected this choice, and hence, varied.

Since there was no component chosen less than 30 times, the

data were not adversely affected by the offer versus serve

tray, and all correlations were statistically valid.

Time Required to Assess Plate Waste

The time (in seconds) to measure the waste of each tray

~n the study was determined (Table 4). In comparing the two

methods, the scrape/weigh method took over twice as long to

perform, averaging 43.72 seconds per tray with the visual

requiring 20.11 seconds. The probability level of the t­

test at which timings for the two methods were considered

significant was 0.05. This data indicated that the

scrape/weigh method is, in fact, a significantly slower

method of determining plate waste when compared to the

visual assessment method. Prior studies (Lachance, 1976;

Comstock, St. Pierre, & Mackiernan, 1981; Stallings &

McKibben, 1982) also indicated this; however, none reported

quantitative data.

Not only was there a time difference between the

scrape/weigh and visual assessment methods, but also, a

difference based on the type of trays available to the

students. Students in kindergarten through second grade

were required to pick up a preserved, standard tray. These

trays included a m~n~mum of five meal components, to meet

31

Table 4: Mean time required per tray to assess plate waste based on observation method.a

Scrape/weighb Visualb Probabili tyc

43.72 + 28.87 20.11 + 14.05 0.000

bHean in seconds + standard deviation

32

the USDA meal pattern guidelines. Third and fourth graders

were given the offer versus serve option. Since the third

and fourth graders tended to eat the items (either more of

or the entire serving) which they had personally chosen,

there was less plate waste. Less, or no plate waste, in

turn, meant that less time was required by the researchers

using either method.

Table 5 reports the average time required to assess

each tray based not only on plate waste method, but also the

type of tray. The data illustrate that offer versus serve

trays reduced the time that was required in using either

plate waste method. For the visual assessment method, this

meant a reduction in time of approximately 40%. Although

the time reduction for the scrape/weigh method was not as

dramatic, it did reduce the time by 14 seconds per tray or

approximately 30%.

Generating the time requirements by plate waste method

and by type of tray could be beneficial to others who will

determine plate waste. With the timing information,

evaluators can estimate how long plate waste measurements

will take, given the type of method chosen, and given the

type of trays offered.

Analysis of Results

The scrape/we1gh method and the visual assessment

method were compared in order to determ1ne if a correlation

33

Table 5: Mean time required per tray to assess plate waste based on type of tray.

Method

Scrape/ Weigh

Visual

Standarda, c

49.45+29.75

23.67+16.60

Offer vs. Serveb, c Probabilityd

35.15+25.17 .0139

14.56+4.59 .0012

cMean in seconds + standard deviation

34

existed. The data showed that the two methods were

extremely close in plate waste results. The visual

assessment method had correlations as high as .99 for

individual menu items. Even when the visual method was used

on individual menu items which were difficult to discern

(such as chicken with the bone intact), the correlation was

still significant at .81.

Two possible reasons can be g1ven for the acquisition

of such reliable data on the visual assessment method in

this study. First, prior to collecting data, plate waste

method training both in-class .and on-site occurred.

Training was used to help ensure that data were collected

and measured in an orderly and systematic fashion. Second,

the researcher responsible for assessing all trays had prior

experience working in the field of school food service.

This comfort and familiarity with the surroundings, types of

foods, and portion sizes may have contributed to a higher

level of accuracy.

Timings of the methods also generated significant

findings. The scrape/weigh method required twice the amount

of time as the visual assessment method. Furthermore, the

time it took to use either method was lengthened when

measuring plate waste from a standard tray, as compared to

an offer versus serve tray.

Depending on one's motivation for determining plate

waste, visual assessment may be the method which suits many

35

purposes. It g1ves a high degree of accuracy, requ1res half

the time of the more traditional scrape/weigh method, allows

one to assess more trays due to time efficiency, requires

inexpensive equipment (paper and pencil), and it is very

easy to do.

CHAPTER V

SUMMARY AND CONCLUSIONS

Plate waste, a long standing problem within the school

food service industry, is measured for a variety of

purposes. Regardless of one's motive for determining plate

waste, an accurate and efficient method needs to be

utilized.

Three generally accepted methods for determ~ning plate

waste are: self-report, scrape/weigh, and visual

assessment. Of the three methods, the scrape/weigh and

visual assessment show the highest degree of correlation

(Comstock, St. Pierre, & Mackiernan, 1981; Holdt, Sitter, &

Gates, 1993). Scrape/weigh, the most precise method in

terms of the quantitative data it generates, has inherent

drawbacks. In general, scrape/weigh is very time consuming.

The visual assessment method, a simpler and faster means of

determining plate waste, is a possible alternative to the

scrape/weigh, although there is a question as to the

accuracy of its data.

This study measured plate waste us~ng both the

scrape/weigh and the visual assessment method. Their

results were compared to determine if v1sual assessment

produced accurate measurements. Time required to determine

waste by both methods also was identified.

36

The null hypotheses which guided this study were:

(1) the correlation for accuracy is low between the visual

assessment and the scrape/weigh method when determining

plate waste; and (2) there is no significant difference 1n

the time required for data collection for the two methods.

Major Findings of the Study

37

Plate waste data were collected for two days. The data

generated from each method were then compared. The

correlation coefficients for the scrape/weigh and the visual

assessment method, for both days, by menu items, were

statistically significant (p<O.OS). Values ranged from .81

to .99. These values were equal to or greater tnan values

found in pr1or studies which concluded that a correlation

did exist between the scrape/weigh and the visual assessment

methods.

The correlatj_ons of .81 and .99 were both from the meat

component. The higher value was the correlation for chicken

nuggets, the lower value, for oven-fried chicken. Although

the oven-fried chicken was more challenging to assess due to

the presence of a bone, it still had a correlation which was

significant. All correlations for individual menu items 1n

this study were statistically significant.

For a determination as to whether there was a time

difference 1n using either of the plate waste methods, every

tray measured for plate waste was also timed. The

38

scrape/weigh method proved to take twice as long per tray as

the visual assessment method.

Further analysis revealed that there was a time

difference based on the plate waste method, and by the type

of tray that was assessed. Students given the offer versus

serve option (as opposed to those who were given a standard

tray) had trays which required less time to assess. Offer

versus serve trays reduced the time that was needed for

assessment using either plate waste method. Using the

scrape/weigh method on an offer versus serve tray reduced

the time minimally, however, for the visual assessment, the

time needed per tray was cut in half.

Impact of the Study

The research from this study accomplished two things:

it showed that a strong relationship does exist between

accuracy of the scrape/weigh and the visual assessment

method, and that a time difference does exist between the

methods. Others who will need to measure plate waste in the

most efficient, and accurate manner would likely find the

results of this research helpful. Although the visual

assessment method is not appropriate for all situations,

particularly if one wishes to determine actual nutrlents

lost through plate waste, it would appear to work, 1n most

instances, quite effectively.

39

Recommendations for Further Research

Three basic recommendations need to be made for further

research. The first recommendation is that further research

which compares the scrape/weigh to the visual assessment

method, use a larger sample size. Although this study

included an acceptable number of observations, a more

comprehensive study could prove more conclusively the extent

to which the methods correlate.

This study suggests that a time difference exists when

collecting data for different plate waste methods. However,

this study did not establish standard times required be

either plate waste method. Therefore, the second

recommendation is that standardized times should be defined

for each method.

Since plate waste can occur 1n any setting which serves

a captive audience, the last recommendation is that the t1me

required for both plate waste methods be determined in other

non-commercial settings. The different methods of serving,

types of customers, and types of food offered, have the

potential to impact the time required for plate waste

methods.

Conclusions

To conclude, the method chosen to assess plate waste

should depend first and foremost, on how the data will

ultimately be used. Also, another basic factor that needs

40

to be considered when choosing a plate waste method is the

amount of resources available for the study. Assuming that

one has a choice in the method used, and is aware that both

methods tend to give accurate results, choosing the visual

assessment method should strongly be considered.

The visual assessment method has many benefic1al

characteristics: it is simple to learn and to use; it

requires inexpensive equipment; twice the amount of data can

be gathered, relative to using scrape/weigh; and most

importantly, data generated from the visual assessment

method are reliable. These points, in addition to the

potential cost savings from the minimal materials needed and

the reduction in staffing hours, should be convinc1ng

arguments toward measur1ng plate waste w1th the visual

assessment method.

REFERENCES

Adam, E., & Ebert, R.J. (1989). Production and operations management: Concepts, models and behav1or (4th ed. ). Englewood Cliffs, NJ: Prentice-Hall.

Chapter IV: Child nutrition programs: A narrat1ve legislative history and program analysis. (1989). School Food Service Research Review, 13,(1), 22-25.

Child Nutrition Act of 1966. Public Law 89-642. October 11, 1966. 89th Congress: U.S. Statutes at Large. Volume 80, p. 885-890.

Coale, E.K., & Bedford, M.R. (1984). Fat-controlled menus 1n a school lunch program. School Food Service Research Review, 8, 37-41.

Comstock, E.M., St. Pierre, R.B., & Mackiernan, Y.D. (1981). Measuring individual plate waste in school lunches. Journal of the American Dietetic Association, 79, 290-296.

Contento, I.R., Manning, A.D., & Shannon, B. (1992). Research perspective on school-based nutrition education. Journal of Nutrition Education, 24(5), 247-260.

DeMicco, F.J. (1990). Identification of barriers that impede school food services from implementing the dietary guidelines. School Food Service Research Review, 14, 10-13.

Devan, K.S., Gregoire, M.B., & Spears, M.C. (1988). Evaluation of a vegetable preparation training program: Part II: Assessment by plate waste observation and student and sensory panel ratings. School Food Service Research Review, 12, 24-27.

Dubois, s. (1990). Accuracy of visual estimates of plate waste in the determination of food consumption. Journal of The American Dietetic Association, 90, 382-387.

Glover, P.K., Stitt, K.R., Kendrick, O.W., & Hayes, J.S. (1991). Dietary guidelines: Knowledge of and use by dietary managers. School Food Service Research Review, 15, 111-113.

Graves, K., & Shannon, B. (1983). Using visual plate waste measurement to assess school lunch behavior. Journal of the American Dietetic Association, 82, 163-165.

41

42

Green, N.R., & Munroe, S.G. (1987). Evaluating nutrient­based nutrition education by nutrition knowledge and school lunch plate waste. School Food Service Research Review, 11, 112-115.

Hiemstra, S.J. (1994). Summary of trends. School Food Service Research Review, 18, 59-60.

Holdt, C.S., Sitter, K., & Gates, G.E. (1993). compar1son of plate waste estimation measures in a pediatric hospital. Journal of Foodservice Systems, 1, 81-90.

Jansen, G.R., & Harper, J.M. (1978). Consumption and plate waste of menu items served in the National School Lunch Program. Journal of The American Dietetic Association, IJ, 395-399.

Kirks, B.A., & Wolff, H.K. (1985). A compar1son ot methods for plate waste determinations. Journal of The American Dietetic Association, 85, 328-331.

Konz, S. (1990). Work design: Industrial ergonomics. Worthington, OH: Publishing Horizons, Inc.

Lachance, P.A. (1976). Simple research techniques for school food service. School Food Service Journal, 34, 68-76.

Lilly, H.D., Davis, D.W., Wilkening, V.L., & Shank, F.R. (1980). Findings of the report on food consumption and nutritional evaluation in the National School Lunch Program. School Food Service Research Review, 4, 7-12.

Maretzkik, A.N. (1979). A prospective on nutrition educat1on and training. Journal of Nutrition Education, 11, 176-180.

National School Lunch Act of 1946. Public Law 79-396. June 4, 1946. 79th Congress: U.S. Statutes at Large. Volume 60, part 1, p. 230-234.

Pannell, D.V. {1990). School foodservice management (4th ed. ). New York: Van Nortstrand Reinhold Publishing.

Read, M.H., & Moosburner, N. (1985). The scheduling of recess and the effect on plate waste at the elementary school level. School Food Service Research Review, 9, 40-44.

Sandoval, W.M., Lockner, D.W., & Adkins, E.W. (1986). Modified school lunch menus based on the dietary guidelines II. Acceptability as determined by plate waste. School Food Service Research Review, 10, 31-34.

43

Schwab, M.G. (1989). Participatory research with children: A new approach to nutrition education. Journal of Nutrition Education, 21, 184B.

Spears, M.C. (1990). Foodservice organizations: A managerial and systems approach. New York: Macmillan Publishing Company.

United States Department of Agriculture. Food and Nutrition Service. Southwest Region (1991). Project 2001: Nutrition for a new century. Dallas: Author.

United States Department of Agriculture and United States Department of Health and Human Services. (1990). Nutrition and your health: Dietary guidelines for Americans (3rd ed., Home and Garden Bulletin No. 232). Washington, DC: Author.

United States Department of Commerce. Economics and Statistics Administration. Bureau of the Census. (1993). Statistical abstract of the United States. (113th ed. ). Washington, DC: U.S. Government Printing Office.

APPENDIX A

PLATE WASTE RECORD

VISUAL ASSESSMENT METHOD

School Name: ------- Grade: 0 1 2 3 4

Date: ------- Sex: 1 2

Race: 1 2 3 4 5

------------------------------------------------------------------------------------------------------------------------COMPONENT/MENU ITEMS OBSERVATION

------------------------------------------------------------------------------------------------------------------------Meat/Meat Alternate

0 1 3 4

------------------------------------------------------------Vegetable/Fruit

0 1 2 3 4

------------------------------------------------------------Vegetable/Fruit

0 1 2 3 4

------------------------------------------------------------Bread/Bread Alternate

Milk Whole

Other

Other

Lowfat 1% Chocolate 1 1/2%

0 1

0 1

0 1

0 1

3 4

2 3 4

2 3 4

3 4

============================================================ 0 = Completely consumed 1 = Majority consumed 2 = 50% consumed 3 = 1 bite to 25% consumed 4 = None consumed

44

SCRAPE/WEIGH METHOD

============================================================ COMPONENT/MENU ITEMS WEIGHT OF WASTE

============================================================ Meat/Meat Alternate

----------------------------------------Vegetable/Fruit

----------------------------------------Vegetable/Fruit

Bread/Bread Alternate

Milk Whole

Other

Lowfat 1% Chocolate 1 1/2%

----------------------------------------Other

============================================================

45

APPENDIX B

BACKGROUND OF RESEARCHERS

1. The primary researcher 1s a graduate student in

Restaurant, Hotel, and Institutional Management.

Her professional experience has primarily been

in school food service, having served 1n the

capacities of assistant, and director of school

food services.

2. The second researcher 1s a graduate advisor and

professor in the department of Restaurant,

Hotel, and Institutional Management. Her

previous professional experience was in hospital

dietetics.

3. The third researcher 1s a graduate student in

Restaurant, Hotel, and Institutional Management.

Her prior professional experience was 1n

journalism and marketing.

46

APPENDIX C

STANDARD WEIGHT RECORD

School Name: -------Date: _________ _

============================================================ COMPONENT/MENU ITEMS WEIGHT (GRAMS)

------------------------------------------------------------------------------------------------------------------------Meat/Meat Alternate

Vegetable/Fruit

Vegetable/Fruit

Bread/Bread Alternate

Milk (Boz)

Whole Lowfat 1% Chocolate 1 1/2%

Other

Other

============================================================

47

APPENDIX D

VISUAL ASSESSMENT PLATE WASTE PROCEDURES

1. Using the pre-selected number of children for the

study, Plate Waste Records are distributed as the

children sit down with their trays.

2. Before leaving forms with the students, demographic

information is filled out, the type of milk chosen is

circled, and lastly, any menu item not picked up by the

student is marked out. Forms are then slid under

trays.

3. Researchers will instruct the students to leave their

trays and forms on the table after finishing lunch.

This is done as an incentive to the participants and to

help researchers keep trays and forms together.

4. Researchers will collect the forms and trays left,

place them on utility carts, and take them to the

dishroom for analysis.

5. In the dishroom, trays are lined 1n rows with the

forms placed under them.

6. When each tray is ready to be assessed, the timing for

it will be started. The timing for each tray is

stopped when the assessment for it is completed. Time

will be taken with a digital stopwatch.

7. One researcher will begin the procedure by visually

assessing each tray, and then calling out the coded

48

49

amounts. A second researcher will record the amounts,

while the third researcher records the time.

APPENDIX E

SCRAPE/WEIGH PLATE WASTE PROCEDURES

1. Using the pre-selected number of children for the

study, Plate Waste Records are distributed as the

children sit down with their trays.

2. Before leaving the forms with the students, demographic

information is filled out, the type of milk chosen is

circled, and lastly, any menu item not picked up by the

student is marked out. Forms are then slid under

trays.

3. Researchers will instruct the students to leave their

trays and forms on table after finishing lunch. This

is done as an incentive to the participants and to help

researchers keep trays and forms together.

4. Researchers will collect the forms and trays left,

place them on utility carts, and take them to the

dishroom for analysis.

5. In dishroom, trays are lined 1n rows with the forms

placed under them.

6. The scrape/weigh procedure begins immediately after all

trays are visually assessed.

7. Each tray is assessed in the same sequential order as

the visual method.

B. Timing will begin for each tray as soon as food is

prepared for weighing. This timing includes food that

50

51

must be separated for accurate measuring (chicken meat

separated from bone, stick removed from corn dog,

etc.). Timing for each tray is stopped after all menu

items on it have been weighed.

9. Weighing of each food item will be accomplished using a

calibrated, digital gram scale.

10. One researcher will scrape all left over food into a

clean, styrofoam container. This will be done for each

menu item. Next, the researcher will call out the

reading to the second researcher who will record the

amount. The third researcher records the time.

APPENDIX F

PLATE WASTE TIME SHEET

SCHOOL

DATE· ______________ _

GRADE: -----------------------

============================================================ VISUAL ASSESSMENT METHOD

============================================================ Number

of Trays Time

MIN: SEC -----------------------

1 ----------------

2

----------------3

4

5

6

7

8

9

10

11

12

===========================================================

52

SCHOOL

DATE: ______________ _

GRADE

============================================================ SCRAPE/WEIGH METHOD

============================================================ Number

of Trays Time

MIN: SEC ------------------------

1

2

3

4

5

6

7

8

9

10

11

12

============================================================

53