Food Science, University of Guelph Guelph, ON N1G 2W1

prittisaini04@gmail.com, arhill@uoguelph.ca Ph: 519-760-5457 (Pritti)

Prabhjot Kaur (Pritti) and Arthur Hill

CONCLUSIONS RESULTS Recombined cream Ø Fat globules in recombined cream relative to

natural cream had similar distribution (unimodal) with slightly larger average size (~5.0 vs 4.0 µm).

Ø Cheddar made from recombined milk had similar composition, sensory & textural properties in contrast to Cheddar made from whole milk.

Ø Cheddar made from homogenized milk or cream had poor quality (taste, texture & color).

Ø Rate of syneresis was slow in cheese curd made from homogenized milk resulting in higher moisture.

Ø Homogenization of milk/cream & fat source used for Cheddar production affected the melting & crystallization behavior of fat in cheese.

Fortified recombined cream Ø The retention levels of vitamin-D3 & omega-3

were approximately proportional to the fat retention in cheese and the losses were proportional to the fat loss in cheese whey.

Ø During short-term storage of 6 months, the levels of vitamin-D3 & omega-3 decreased by 4.7% and 9.8% respectively.

Ø Sensory quality of cheese was not affected due to fortification with vitamin D3 (~18087 IU kg-

1) & algal oil (~3.12 g kg-1) up to 3 months of ripening.

Ø Hardness of cheese was not affected due to fortification up to 5.5 months of ripening.

Cheddar made from Whey Protein Stabilized and Vitamin Fortified Recombined Cream

INTRODUCTION Ø Production of cheese from recombined

milk is necessary in countries or regions with low or fluctuating milk supply. Preparation of recombined milk normally requires homogenization that produces fat globules stabilized mainly with caseins, which actively participate in milk gelation and result in poor quality cheese (Jana and Upadhyay, 1992).

Ø In Canada, only a few products are fortified with Omega-3 e.g., eggs & DHA milk. For individuals with lactose intolerance & those who do not otherwise eat fish or eggs or drink milk, cheese is a viable source of vitamin D & omega-3.

Ø 32% of the population had insufficient levels of vitamin-D (Statistics Canada, 2013) & Canadian’s fish consumption is also well below Canada’s Food Guide (RIAS Inc., 2013). Therefore, fortification of commonly consumed foods with vitamin-D & omega-3 is a promising means to increase the level of these nutrients in the Canadian’ diet.

Ø The aim of this research was to assess the recombined cream for cheese making in contrast to natural cream & its fortification to increase nutritional value of cheese.

Ø The current project demonstrated for the first time that good quality Cheddar cheese can be produced from recombined milk without the well-known quality defects found in cheese made from homogenized milk. To our knowledge, this study is also the first to demonstrate algal oil (DHA+EPA) & vitamin D3 fortification of Cheddar cheese using recombined cream as the carrier.

Ø No other researchers have studied melting & crystallization of fat in cheese by DSC & polarized light microscopy. These new observations suggest more research to develop applications of DSC & PLM to study properties of fat in situ in cheese & other food.

Ø The simple technique designed to monitor syneresis of cheese curd may be of interest to other researchers.

Surface Images of 5 day ripened Cheddar cheeses

First from top (Control cheese), Second (RM cheese), Third (HM cheese), Fourth on bottom (RMS cheese): Images showing surface defects in cheeses made from homogenized milk/cream (HM and RMS)

Cheese plugs obtained from 3 month ripened Cheddar cheeses. Top right (RM cheese), Top left (control), Bottom

right (HM cheese), Bottom left (RMS cheese): Image showing color and texture differences among treatments

OMAFRA and DFO supported this Research

1

Ø Recombined cream preparation • Whey protein concentrate (WPC35)

solution was heated at 70°C for 11 min using UHT/HTST pasteurizer. Heat treated whey protein solution (2.4% protein) & melted butter or butter oil (BO) were mixed together in 70:30 ratios. The mixture was heated to 60°C & emulsified using a high-speed blender at 11,000 rpm for 12 minutes.

Ø Fortified recombined cream preparation

• Vitamin-D3 & Algal oil (DHA+EPA) were added separately to the fat phase (melted butter) of the recombined cream in appropriate amounts before emulsification.

Ø Cheese milk preparation • Control milk was prepared using natural

cream (35%) & skim milk. • Homogenized milk (HM) was prepared

using control milk which was homogenized at about 60°C using first stage at 1500 psi.

• Recombined milks (RML, RML-BO) were prepared using recombined cream (made using butter or butter oil) & skim milk.

2

• Homogenized recombined milk (RMS) was prepared by blending WPC solution & butter mixture at 5500 rpm for 2 minutes, followed by homogenization at about 60°C using first stage at 2500 psi & second stage at 500 psi with 2-3 passes through homogenizer.

Ø Melting & crystallization behavior of fat in cheese

• Thermal transitions and fat crystals in Cheddar cheeses were determined by using Differential Scanning Calorimetry (DSC) & Polarized light microscopy (PLM).

Ø Syneresis • Syneresis was monitored using newly designed

experiment in which the rate of syneresis was calculated by measuring the weight of whey drained from the curd as a function of time.

Ø Descriptive and consumer sensory analysis

• Descriptive analysis was conducted for control, RML, RML-BO, HM & RMS cheeses as described by Meilgaard, Civille and Carr (1999) in Sensory Evaluation Techniques, 3rd Ed. & was performed by 10 trained panels. Traingle test was performed for fortified cheese samples by 48 consumer panels.

METHODS

Graph showing size & distribution of fat globules in natural & recombined cream/milk samples made from non homogenized & homogenized milk

0

2

4

6

8

10

12

14

0.01 0.1 1 10 100 1000

Control

RML cream

RML-BO cream HM milk

RMS milk

Fat globule size (µm)

Part

icle

size

dis

trib

utio

n (%

)

Sensory results

Syneresis experiment

Nutrient stability over time

0 10 20 30 40 50

Control RML RML-BO HM RMS

Temperature ° C

0 5 10 15 20 25

Control

RML

RML-BO

HM

RMS Temperature °C

DSC curves: Melting of fat in cheese DSC curves: Crystallization of fat in cheese