Post-Harvest Nutrient Retention and Shelf Life of Organic and Conventional Produce
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Post-Harvest Nutrient Retention and Shelf Life of Organic and Conventional Produce Sanaa Bhatti 1 , Rachel Powell 1,2 , Maureen Xu 3 1 Department of Health and Human Performance 2 Department of Biological and Health Sciences, Meredith College 3 North Carolina School of Science and Math Background Objectives Methods Results Conclusion References Acknowledgements: Meredith College Department of Health and Human Performa Meredith College Department of Biology Dr. William Landis, Dr. Karthik Aghoram, Dr. Romita Sen Ogburn’s Berries and Produce, Lee’s Produce, Wild Hare Fa -------------------------- This research was supported by the Meredith College Environmental Sustainability Initiative There is a long-held assumption that produce grown organically and picked locally provides better overall nutritive value to the consumer than its conventional counterpart, which is shipped and consumed farther from its source. While it is known that the overall quality of produce diminishes as a function of time and temperature, data on the nutrient quality of produce over time has not been substantiated 1 . In addition, there is evidence to suggest that some organic produce has a greater shelf-life than conventional produce due to higher levels of antioxidant and antimicrobial phytochemicals found in organically produced crops 2,3 . While clear benefits to the environment of organic and local foods exist, nutrition and health benefits are more equivocal.. -Samples were picked fresh off the plant from 4 different farms, kept cool on ice during transportation, then sanitized in a bleach vinegar solution. -Fresh produce was divided into 3 groups- to be frozen immediately, to be refrigerated for 1 week, and to be refrigerated for 2 weeks. -Produce not immediately frozen was stored in plastic containers placed in cardboard boxes to simulate transportation methods used by large conventional farmers. - Several 1g samples were weighed and frozen using liquid nitrogen. -Frozen samples were homogenized in citric acid buffer and centrifuged to extract the Vitamin C. -The supernatant was mixed with citric acid and DCPIP. Absorbency was read using a spectrophotometer. -Absorbency values were analyzed using a standard curve, that was run every day. Utilizing the rich agricultural tradition of NC and the analytical capabilities available at Meredith College, this project evaluates the shelf life and nutrient retention between several types of organic and conventional fresh produce over a 2 week period, equivalent to the typical journey of much of the nation’s produce. Vitamin C was measured and served as an indicator of labile essential nutrients in the food samples. Ascorbic acid content (AA) of tomatoes varies by variety as well as stage of ripeness. Tomatoes of the same variety picked before they reach maturity had significantly lower levels of vitamin C than those picked in later stages of ripening. Mexican hot house tomatoes yielded the highest levels of AA in analysis, followed by local purple varieties, Canadian hot house, and local yellow varieties, listed respectively. AA content of green peppers varied by agricultural farming method. Organic green peppers demonstrated overall higher levels of AA than their conventional counterparts. AA levels of broccoli were not conclusive. Organic broccoli yielded higher levels of AA than conventionally grown broccoli in day 0 and day 14 measurements, but lower levels in day 7 measurements. This could be due to lack of consistency in sampling, with variations in individual produce acting as a confounding variable. This variable could also contribute to the absence of a linear decline in AA values over the 2-week sampling/shelf life periods. 1. Vigneault C, Thompson, J, Wu, S, Hui, K, LeBlanc, D. Transportation of Fresh Horticultural Produce. Postharvest Technologies for Horticultural Crops, 2009, Vol2:1-24 2. Going Organic: What’s the Payoff? Interview with Charles Benbrook. Spoke to David Schardt. Nutrition Action Health Letter, Center for Scoinec in the Public Interest, Oct 2012. 3. Benbrook, C. The Organic Center. State of Science Review Executive Summary, Number 2. Elevating Antioxidant Levels in Food Through Organic Farming and Food Processing., January 2005. Student Researchers Sanaa and Rachel harvesting fresh kale at Ogburn’s Berries and Produce, NC Vitamin C Values in mg/100 g Day 0 Day 7 Day 14 Green Pepper Conventiona l 57.135 56.44 87.23 Organic 96.99 89.51 123.32 Broccoli Conventiona l 26.85 36.45 29.89 Organic 35.93 28.13 32.66 Tomato Vitamin C Values in mg/100 g Mexican, Red 36.5 3 Canadian Hot House, Red 25.0 6 Local, Farmer’s Market, Red 21.5 0 Local, Picked Ripe, Red 20.0 0 Local, Picked Half-Ripe, Red 15.6 9 Local, Picked Green 7.64 Local, Farmer's Market, 19.6 Mexican , Red Canadia n Hot House, R ed Local, Farmer' s Marke t, Red Local, Picked F resh, Red Local, Picked Half-Ri pe, Red Local, Picked Green Local, Farmer's Marke t, Yellow Local, Farmer's Marke t, Purpl e 0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 Tomato Vitamin C Values Tomato Varieties Amount in mg/100 g Conventional Green Pepper Organic Green Pepper Conventional Broccoli Organic Broccoli 0 20 40 60 80 100 120 140 Green Pepper and Broccoli Vitamin C Values Day 0 Day 7 Day 14 Amount of Vitamin C in mg/100 g Sanaa and Rachel working on vitamin C extraction and analysis
description
Post-Harvest Nutrient Retention and Shelf Life of Organic and Conventional Produce Sanaa Bhatti 1 , Rachel Powell 1,2 , Maureen Xu 3 1 Department of Health and Human Performance 2 Department of Biological and Health Sciences, Meredith College - PowerPoint PPT Presentation
Transcript of Post-Harvest Nutrient Retention and Shelf Life of Organic and Conventional Produce
Post-Harvest Nutrient Retention and Shelf Life of Organic and Conventional ProduceSanaa Bhatti1, Rachel Powell1,2 , Maureen Xu3
1 Department of Health and Human Performance 2 Department of Biological and Health Sciences, Meredith College 3 North Carolina School of Science and Math
Background
Objectives
Methods Results Conclusion
References
Acknowledgements:Meredith College Department of Health and Human Performance
Meredith College Department of BiologyDr. William Landis, Dr. Karthik Aghoram, Dr. Romita Sen,
Ogburn’s Berries and Produce, Lee’s Produce, Wild Hare Farms--------------------------
This research was supported by the Meredith College Environmental Sustainability Initiative
There is a long-held assumption that produce grown organically and picked locally provides better overall nutritive value to the consumer than its conventional counterpart, which is shipped and consumed farther from its source. While it is known that the overall quality of produce diminishes as a function of time and temperature, data on the nutrient quality of produce over time has not been substantiated 1. In addition, there is evidence to suggest that some organic produce has a greater shelf-life than conventional produce due to higher levels of antioxidant and antimicrobial phytochemicals found in organically produced crops2,3. While clear benefits to the environment of organic and local foods exist, nutrition and health benefits are more equivocal..
-Samples were picked fresh off the plant from 4 different farms, kept cool on ice during transportation, then sanitized in a bleach vinegar solution. -Fresh produce was divided into 3 groups- to be frozen immediately, to be refrigerated for 1 week, and to be refrigerated for 2 weeks. -Produce not immediately frozen was stored in plastic containers placed in cardboard boxes to simulate transportation methods used by large conventional farmers.- Several 1g samples were weighed and frozen using liquid nitrogen. -Frozen samples were homogenized in citric acid buffer and centrifuged to extract the Vitamin C. -The supernatant was mixed with citric acid and DCPIP. Absorbency was read using a spectrophotometer. -Absorbency values were analyzed using a standard curve, that was run every day.
Utilizing the rich agricultural tradition of NC and the analytical capabilities available at Meredith College, this project evaluates the shelf life and nutrient retention between several types of organic and conventional fresh produce over a 2 week period, equivalent to the typical journey of much of the nation’s produce. Vitamin C was measured and served as an indicator of labile essential nutrients in the food samples.
Ascorbic acid content (AA) of tomatoes varies by variety as well as stage of ripeness. Tomatoes of the same variety picked before they reach maturity had significantly lower levels of vitamin C than those picked in later stages of ripening. Mexican hot house tomatoes yielded the highest levels of AA in analysis, followed by local purple varieties, Canadian hot house, and local yellow varieties, listed respectively. AA content of green peppers varied by agricultural farming method. Organic green peppers demonstrated overall higher levels of AA than their conventional counterparts. AA levels of broccoli were not conclusive. Organic broccoli yielded higher levels of AA than conventionally grown broccoli in day 0 and day 14 measurements, but lower levels in day 7 measurements. This could be due to lack of consistency in sampling, with variations in individual produce acting as a confounding variable. This variable could also contribute to the absence of a linear decline in AA values over the 2-week sampling/shelf life periods. 1. Vigneault C, Thompson, J, Wu, S, Hui, K, LeBlanc, D. Transportation of Fresh
Horticultural Produce. Postharvest Technologies for Horticultural Crops, 2009, Vol2:1-24
2. Going Organic: What’s the Payoff? Interview with Charles Benbrook. Spoke to David Schardt. Nutrition Action Health Letter, Center for Scoinec in the Public Interest, Oct 2012.
3. Benbrook, C. The Organic Center. State of Science Review Executive Summary, Number 2. Elevating Antioxidant Levels in Food Through Organic Farming and Food Processing., January 2005.
Student Researchers Sanaa and Rachel harvesting fresh kale at Ogburn’s Berries and Produce, NC
Vitamin C Values in mg/100 g Day 0 Day 7 Day 14
Green PepperConventional 57.135 56.44 87.23Organic 96.99 89.51 123.32
BroccoliConventional 26.85 36.45 29.89Organic 35.93 28.13 32.66
Tomato Vitamin C Values in mg/100 g
Mexican, Red 36.53
Canadian Hot House, Red 25.06
Local, Farmer’s Market, Red 21.50
Local, Picked Ripe, Red 20.00
Local, Picked Half-Ripe, Red 15.69
Local, Picked Green 7.64
Local, Farmer's Market, Yellow 19.62
Local, Farmer's Market, Purple 28.75
Mexican, Red
Canadian Hot
House, Red
Local, Farmer's Market,
Red
Local, Picked Fresh, Red
Local, Picked
Half-Ripe, Red
Local, Picked Green
Local, Farmer's Market, Yellow
Local, Farmer's Market, Purple
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Tomato Vitamin C Values
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Conventional Green Pepper
Organic Green Pepper
Conventional Broccoli
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Green Pepper and Broccoli Vitamin C Values
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Sanaa and Rachel working on vitamin C extraction and analysis
