Progress 12/01/11 to 11/30/16
Outputs
Target Audience:Food industry Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?2 graduate students were trained while conducting this project. How have the results been disseminated to communities of interest?The results have been presented at professional conferences and also published in peer-reviewed journals. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
The first part of this study compared the effects of apple puree addition on a model fruit cocktail system heated in a rapid-heating conventional 2450 MHz microwave oven to a slow-heating water bath system. No significant changes in Vitamin C content occurred during heating, while total phenolic levels increased, presumably due to enhanced extraction from fruit tissue. Decreases in Vitamin C content were observed over two days of storage, however. The manuscript for this portion of the study has been written and will be sent to a peer-reviewed journal for consideration for publication. The second part of the study utilized a continuous-flow stacked 2450 MHz microwave system to examine the effects of processing on diced and pureed apple samples with or without Vitamin C pre-treatment. Pureed samples maintained more nutrients than diced samples. Vitamin C pre-treatment was an effective means of retaining nutrients, regardless of whether apples were diced or pureed. The manuscript for this portion of the study has been written and will be sent to a peer-reviewed journal for consideration for publication. Taken together, these studies indicated that Vitamin C, phenolics, and antioxidant properties are stable to microwave-based heat processing, but that nutrients are lost during storage. Increased phenolic content measured in processed samples may have resulted from improved extraction. Both studies highlighted the importance of inactivating degradatory enzymes in apples. The manuscript for this portion of the study has been written and will be sent to a peer-reviewed journal for consideration for publication. As far as the process validation part goes, the folloqing was ccomplished. Monitoring mitochondrial DNA fragmentation was proposed and tested as a molecular tool to validate thermal processing of plant-derived food products and biomaterials. Increases in the cycle threshold (Ct) as the result of quantitative polymerase chain reaction was used to quantify plant-derived mithocondrial DNA fragmentation of food materials during processing. Using sweet potato puree as a model low-acid product, Ct value was highly correlated to time-temperature treatment; the logarithmic reduction (log CFU/ml) of the spore-forming Clostridium botulinum, Geobacillus stearothermophilus; and cumulative F value (min) in a canned retort process, all comparisons conducted at 121°C. The method is especially useful for thermal processes over 100 °C, since temperatures above boiling rapidly damage DNA which can be quantified by the increase in cycle threshold (Ct) value of the quantitative polymerase chain reaction (qPCR). The method has advantages over the current methods using time and temperature sensitive enzymatic assays given that mitochondrial DNA is highly stable and can be stored at freezing temperatures for an extended period of time. This rapid molecular method can be used as a new tool for validation and/or monitoring thermal processing of low-acid and high-acid foods. The mtDNA fragmentation method was also assessed in acidified foods such as fermented and acidified cucumbers to determine the potential of this tool for process validation and forensic DNA testing on vegetable fermentation times and shelf-life of acidified, plant-derived products, given that acids can degrade DNA. Ct values were measured from fresh, fermented, pasteurized and stored cucumber mtDNA and determined to be significantly different (p>0.05) based on processing and shelf-life. This indicated that the combination of lower temperature thermal processes (hot fill at 75 °C for 15 min) and acidified conditions (pH = 3.8) was sufficient to cause mtDNA fragmentation. In studies modeling high acid juices, pasteurization (96 °C, 0-24 min) of tomato serum produced Ct values which had high correlation to time-temperature treatment. The sensitivity of the technique was improved by using primers producing longer amplicons (~1 kb) targeting the same mitochondrial gene. Mitochondrial DNA fragmentation was shown to be a potential new tool to monitor low-temperature (<100 °C) high acid processes (pH<4.6), and non-thermal processes such as vegetable fermentation times and shelf-life of acidified, plant-derived products. A provisional USA patent and a provisional international patent have been filed for this technology. Attempts to use the technology to monitor peanut roasting were less successful. Mitochondrial DNA fragmentation was not linear compared to time at a given temperature, but exhibited a long lag time. D and z-values were calculated using E. faecium, threshold cycle (Ct) and Hunter L color values. D values for E. faecium were 2.68, 2.06 and 1.89 min for 138, 153 and 167°C roasting temperatures, respectively. The E. faecium z-value was very large (192°C) as microbial destruction in dry, roasted nuts does not exhibit true first-order kinetics, but has significant tailing. Mitochondrial DNA fragmentation as measured by Ct had a D value of 12.3 min at a roasting temperature of 167°C which was slightly higher than "wet" processes (ca. 11.5 min). Mitochondrial DNA fragmentation as measured by Ct value was deemed too variable for thermal process or quality validation of dry, solid foods such as peanuts. However, it could be used to evaluate penetration of heat through a solid food matrix, to find the coldest spot and test the worst-case scenario.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
14. Caldwell, J.M., Perez-Diaz, I.M., Harris, K., Hassan, H.M., Simunovic, J., Sandeep, K.P. 2015. Mitochondrial DNA fragmentation to monitor processing parameters in high acid, plant-derived foods. Journal of Food Science. Vol. 80(12): M2892-2898.
15. Caldwell, J.M., Perez-Diaz, I.M., Sandeep, K.P., Simunovic, J., Harris, K., Osborne, J.A., Hassan, H.M. 2015. Mitochondrial DNA fragmentation as a molecular tool to monitor thermal processing of plant-derived, low-acid foods, and biomaterials. Journal of Food Science. Vol. 80(8): M1804-M1814.
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Progress 12/01/14 to 11/30/15
Outputs
Target Audience:Food industry Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?2 graduate students were trained How have the results been disseminated to communities of interest?The results were presented at the annual IFT meeting What do you plan to do during the next reporting period to accomplish the goals?We plan to complete the project during the next time period. THis would involve both the microbiology and nutrition aspects.
Impacts
What was accomplished under these goals?
The goals of this project are to develop an understanding of the relative rates of heating of the solid and liquid fractions in a particulate product that has constituents of different physical, thermal, and dielectric properties and to engineer the system and process parameters to maximize the nutrient retention and texture/integrity of the particulates. The specific objectives of this project are to determine the temperatures at various points within the products under consideration for different processes, minimize the temperature differences, optimize the system & process parameters to produce a safe and high quality product. A time-temperature integrator (TTI) for assessing thermal processing efficacy using mitochondrial DNA (mtDNA) and quantitative PCR (qPCR) was developed. Ct values from fresh, fermented, pasteurized, and stored cucumber mtDNA were determined to be significantly different (p>0.05) based on processing and shelf-life. The combination of lower temperature (hot fill at 75 °C for 15 min) and acidified conditions (pH = 3.8) was sufficient to cause mtDNA fragmentation. Pasteurization (96 °C, 0-24 min) of tomato serum produced Ct values which had high correlation to time-temperature treatment. Mitochondrial DNA fragmentation is a potential new tool to characterize low-temperature (<100 °C) high acid processes (pH<4.6), non-thermal processes such as vegetable fermentation. Further study includes evaluation of 5D and 12D processes, comparing E. coli O157:H7 and G. stearothermophilis kill curves to this TTI. Two experiments were conducted to determine nutrient retention in fruit purees. Muscadine grapes and apple peels were combined with pineapple and peach puree. Individual ingredients along with the formulations containing grapes or apple peel with pineapple and peach puree were heated in an oil bath at 95 °C (3, 4, 5 min). Phenolics were extracted with acidified methanol and analyzed for total phenolics (TP) and antioxidant activity (AA) using respectively Folin-Ciocalteu and DPPH method. Muscadine skin puree had the highest TP and AA, 2429.7 µg gallic acid (GA)/g fw and 681.2 Trolox µM/g fw, respectively. Muscadine skin puree containing peach and pineapple had the highest amounts of TP (1815.3 µg GA/g fw) and AA (491.3 Trolox µM/g fw) of all formulations. There was a slight increase in TP and AA in most pureed samples as processing time increased suggesting that the purees contain time and heat released antioxidants. In the next experiment, apple purees were formulated with peach and pineapple purees and processed at 100 °C in a 2,450 MHz microwave oven (rapid heating, 50 sec come up time) or at 95 °C in an agitating hot water bath (slow heating, 5 min come up time) for 1, 2, and 3 min hold times. Samples were analyzed immediately after processing or refrigerated (4 °C) for 2. Samples were analyzed for total phenolics by the Folin Ciocalteu assay, total antioxidant capacity by the oxygen radical absorbance assay (ORAC), and total ascorbic acid content using HPLC. Thermally processed samples of peeled and unpeeled apple puree-based fruit cocktail showed significant increases (42%) in total phenolics as compared with unprocessed samples. Peeled fruit cocktail samples processed with 3 min holding time had the highest total phenolic content of 1,509 μg gallic acid equivalents/g fresh weight. No significant decreases in ascorbic acid content and antioxidant activity were observed between unprocessed and thermally processed fruit cocktail samples. However, there were significant decreases in ascorbic acid content after 2-day storage, 73-83% and 10-62% in unprocessed and thermally processed fruit cocktail samples, respectively. The next step is to scale up the microwave experiment to a small pilot scale with a fruit cocktail formulation. From there, a large scale run will be conducted to determine nutrient retention and validate the process using Vitamin C degradation kinetics.
Publications
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Progress 12/01/13 to 11/30/14
Outputs
Target Audience:Food industry Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?2 graduate students have been trained during the process. How have the results been disseminated to communities of interest?Publication in journal What do you plan to do during the next reporting period to accomplish the goals?We plan to complete the process validation protocol and complete the experiments related to continuous flow microwave processing of low- and high-acid products.
Impacts
What was accomplished under these goals?
The thermal processing protocol for continuous flow microwave processing of low- and high-acid foods was developed. The technique to conduct process validation is being developed.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
2. Caldwell, J.M., Perez-Diaz, I.M., Sandeep, K.P., Simunovic, J., Harris, K., Osborne, J.A., Hassan, H.M. 2015. Mitochondrial DNA fragmentation as a molecular tool to monitor thermal processing of plant-derived, low-acid foods, and biomaterials. Journal of Food Science. Vol. 80(8): M1804-M1814.
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Progress 12/01/12 to 11/30/13
Outputs
Target Audience:Food processing industry personnel andregulatory agencies interested in process validation Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Two graduate students have been trained to coduct research work related to food processing, microbiology, and nutrition. How have the results been disseminated to communities of interest?The results of the project have been presented at various national and international meetings. Onemanuscript has already been published and several others will follow. What do you plan to do during the next reporting period to accomplish the goals?The next step is to scale up the microwave experiment to a small pilot scale with a fruit cocktail formulation. From there, a large scale run will be conducted to determine nutrient retention and validate the process using Vitamin C degradation kinetics.
Impacts
What was accomplished under these goals?
The goals of this project are to develop an understanding of the relative rates of heating of the solid and liquid fractions in a particulate product that has constituents of different physical, thermal, and dielectric properties and to engineer the system and process parameters to maximize the nutrient retention and texture/integrity of the particulates. The specific objectives of this project are to determine the temperatures at various points within the products under consideration for different processes, minimize the temperature differences, optimize the system & process parameters to produce a safe and high quality product. A time-temperature integrator (TTI) for assessing thermal processing efficacy using mitochondrial DNA (mtDNA) and quantitative PCR (qPCR) was developed. Ct values from fresh, fermented, pasteurized, and stored cucumber mtDNA were determined to be significantly different (p>0.05) based on processing and shelf-life. The combination of lower temperature (hot fill at 75 °C for 15 min) and acidified conditions (pH = 3.8) was sufficient to cause mtDNA fragmentation. Pasteurization (96 °C, 0-24 min) of tomato serum produced Ct values which had high correlation to time-temperature treatment. Mitochondrial DNA fragmentation is a potential new tool to characterize low-temperature (<100 °C) high acid processes (pH<4.6), non-thermal processes such as vegetable fermentation. Further study includes evaluation of 5D and 12D processes, comparing E. coli O157:H7 and G. stearothermophilis kill curves to this TTI. Two experiments were conducted to determine nutrient retention in fruit purees. Muscadine grapes and apple peels were combined with pineapple and peach puree. Individual ingredients along with the formulations containing grapes or apple peel with pineapple and peach puree were heated in an oil bath at 95 °C (3, 4, 5 min). Phenolics were extracted with acidified methanol and analyzed for total phenolics (TP) and antioxidant activity (AA) using respectively Folin-Ciocalteu and DPPH method. Muscadine skin puree had the highest TP and AA, 2429.7 µg gallic acid (GA)/g fw and 681.2 Trolox µM/g fw, respectively. Muscadine skin puree containing peach and pineapple had the highest amounts of TP (1815.3 µg GA/g fw) and AA (491.3 Trolox µM/g fw) of all formulations. There was a slight increase in TP and AA in most pureed samples as processing time increased suggesting that the purees contain time and heat released antioxidants. In the next experiment, apple purees were formulated with peach and pineapple purees and processed at 100 °C in a 2,450 MHz microwave oven (rapid heating, 50 sec come up time) or at 95 °C in an agitating hot water bath (slow heating, 5 min come up time) for 1, 2, and 3 min hold times. Samples were analyzed immediately after processing or refrigerated (4 °C) for 2 days. Samples were analyzed for total phenolics by the Folin Ciocalteu assay, total antioxidant capacity by the oxygen radical absorbance assay (ORAC), and total ascorbic acid content using HPLC. Thermally processed samples of peeled and unpeeled apple puree-based fruit cocktail showed significant increases (42%) in total phenolics as compared with unprocessed samples. Peeled fruit cocktail samples processed with 3 min holding time had the highest total phenolic content of 1,509 μg gallic acid equivalents/g fresh weight. No significant decreases in ascorbic acid content and antioxidant activity were observed between unprocessed and thermally processed fruit cocktail samples. However, there were significant decreases in ascorbic acid content after 2-day storage, 73-83% and 10-62% in unprocessed and thermally processed fruit cocktail samples, respectively.
Publications
- Type:
Journal Articles
Status:
Accepted
Year Published:
2015
Citation:
Mitochondrial DNA fragmentation as a molecular tool to monitor thermal processing of plant-derived, low-acid foods, and biomaterials
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Progress 12/01/11 to 11/30/12
Outputs
OUTPUTS: Two graduate students were hired to conduct the research work. They have conducted preliminary studies to develop the parameters required to create their design of experiments. They have fabricated some of the equipment needed to conduct the studies. Experiments have been planned for and will be conducted in the following months. PARTICIPANTS: An Truong and Jane Caldwell are the graduate students working on this project. TARGET AUDIENCES: Food industry is the target audience for this work. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
No results to report yet.
Publications
- No publications reported this period
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