Progress 09/01/13 to 08/31/18
Outputs
Target Audience:The target audiences of this project include researchers and students in food science, viticulture and enology, food safety regulation officers, grape farmers and winery owners, health professional, food industry and consumers. Changes/Problems:The major changes include Two No Cost Extensions were requested due to the lack of graduate students in first and second year of the project and due to sample mishandling which resulted in unreliable results. We changed the approved protocol regarding detoxification of OTA by ozonization to acid treatment and enzymatic treatment due to the concern of polyphenol destruction by ozone. What opportunities for training and professional development has the project provided?Two undergraduate students and one graduate student were involved in the project during this period. They were trained to conduct OTA extraction and evaluation ofthe impact of different detoxification methods on different types of polyphenolsof grape pomace. Thepostdoc Bonice Karlton-Senaye conducted mold enumerating, characterization and confirmation.She is now working in a food company. Two temporary research assistants Ivy Smith and Nona Mikiashvili were fully trained to conduct OTA extraction, analysis and detoxification of OTA by different processing methods. Ivy Smith is now working in a food company in the area of fresh produce safety. How have the results been disseminated to communities of interest?The results of this project have been disseminated in state, regional and national conferences, graduate seminar class, North Carolina Annual Small Farms Week, and NC A&T Small Farmer Field Day. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
During the period of 09/01/2013 - 08/30/2018, the project team completed all proposed objectives. Objective 1. Evaluating the mycotoxin levels in the fresh pressed GP samples collected from different wineries in North Carolina: The GPs of seven cultivars were collected from two North Carolina wineries. Ochratoxin A (OTA) levels in seven wet and dried GP samples were determined by Enzyme-Linked Immunosorbent Assay (ELISA) method using the analytical kits purchased from Romer Labs Inc (Union, MO) and compared to the results obtained by High-Performance Liquid Chromatography (HPLC) analysis. OTA was detected in all fresh pomace samples collected. The level of OTA in the pomace varied with grape cultivars (10.99±3.45 to 35.96±2.61ng/g pomace). Muscadine Noble and Sangiovese pomaces showed lowest but Chardonnay pomace showed the highest OTA content. The order of OTA contents of wet pomace samples is; Chardonnay >Muscadine Carlos ≥ Cabernet Franc ≥ Merlot ≥ Cabernet Sauvignon> Sangiovese > Muscadine Noble. For the same pomace sample, the OTA content determined by HPLC method was significantly lower than that determined by ELISA kit. Objective 2. Characterizing the existence of pathogenic fungi in the GP samples: The population of yeast and mold in each pomace sample were determined using three different agars (DBRC, PDA, and DG18), the morphologies of the isolated mold species were characterized based on colony appearance, color, exudates and colony diameter on CYA, PDA, and MEA. The highest population of mold (5.35±0.04 log CFUml-1) was detected in pomace made from Chardonnay wine grape. No mold was detected in pomace obtained from Cabernet Franc, and Sangiovese wine grape. Aspergillus niger (81.1%) was found to be the major source of contamination and most frequently isolated fungal species. Other fungal isolates were A. carbonarius (13.51%) and A. fumigatus (5.39%). Objective 3. Evaluating the effects of different drying methods on fungal inactivation, OTA content and polyphenol retention in GP: The GP samples were dried by freeze drying (48 hrs), room temperature drying (one week) and vacuum drying (24 hrs), respectively. Part of each dry sample was ground into powder, the rest was separately into seeds and skins which were then ground into powder. Each dried pomace sample was tested for mold counts using direct plating method. The mold count and OTA level of each sample were measured. The OTA contents of wet pomaces were used as controls. Drying method has significant effects on the viability of OTA producing molds and OTA content of GP. The mold colony counts of vacuum, freeze and room temperature dried samples were in the range of 0-3, 1-5 and 0-300 colonies/g dry pomace, respectively. Regardless grape cultivar, seeds showed higher OTA content than skins with exception of Muscadine Carlos pomace. Vacuum dried seeds showed lowest OTA contents, while freeze-dried seeds showed highest OTA content. For the same drying method, the OTA content of Chardonnay grape seeds was the highest. Therefore, a quick drying method such as vacuum drying could efficiently inactivate OTA producing molds and spores and reduce OTA content in the pomace, thus improving the safety of grape pomace. Objective 4: evaluating the detoxification effects of selected food processing methods such as baking, pressure cooking, and ozonization: We evaluated the effectiveness of baking, pressure cooking, acid treatment and enzymatic treatment on the OTA contents in the grape pomace. To protect polyphenols in the GP, we did not evaluate the ozonization method because ozonization may cause oxidation of phenolic compounds. Cookie baking was used as a baking model. GP powder (2.5-10%) was added to cookie formula and the cookie dough was spiked with purified OTA. Dough and Cookie without GP and spiked OTA were used as controls. Results show that baking of cookies did not reduce OTA content. Instead, the OTA contents of cookies samples were higher than those of dough for each type of grape pomace. The higher OTA contents in cookies compared to dough may be that baking increased the extractability of OTA due to the structural change of food matrix caused by baking. Therefore, the regular baking method could not reduce OTA content in food products. Pressure cooking was done autoclaving wet GP samples for 20 min at 121°C. Autoclave greatly reduced OTA content of GP samples tested. The OTA reduction was 72-91% for wet GP samples and 74-88% for dry GP samples. However, the autoclave also resulted in the loss of GP polyphenols including flavonoids and anthocyanin. Therefore, thermal-pressure treatment of GP could be an effective detoxification method to improve the safety of grape pomace at the cost of reduced polyphenol content. For acid treatment, hydrochloric acid, acetic acid, citric acid, and lactic acid were tested. The GP was mixed with each acid to pH 2.0 and then autoclaved for 20 min. The effectiveness of different acids in OTA reduction varied with the variety of GP, but less effective than autoclave. More study is needed. For enzymatic treatment, six enzymes (Alcalase, papain, pepsin, flavourzyme, lipase, carboxypeptidase A) were tested. The enzyme was added to the purified OTA solution at a concentration of 10mg/µg OTA and incubated at 37°C for 3-24 hours. Among all enzymes tested, carboxypeptidase A was the most effective in OTA reduction, flavourzyme and lipase showed certain OTA reducing activity, but other enzymes did not show an effect on OTA under the experimental condition of this study. These three enzymes were selected to treat OTA spiked GP samples, separately, for 24 hrs, but only lipase and carboxypeptidase A resulted in 10-11% OTA reduction. Impacts The results of this project show that most ofthe GP samplescontain viable pathogenic molds and OTA, which are not safe for direct consumption by either human or animal. However, the molds can be killed by different methods such as quick drying, autoclave, and high acidity treatment; and the OTA level in GP can be effectively reduced to the safe level by pressure cooking and acid treatment treatments. Therefore, the safety of the grape pomace can be improved. Other by-products of commercial fruit processing such as apple pomace may also be subjected to mold and mycotoxin contamination. The findings of the project are important to those who are interested in using GP and other fruit by-products as a food ingredient or part of animal feed. In addition,it is important for those who are interested using GP or other fruit by-products to produce polyphenol extracts to considerdestroying/reducing mycotoxinsbecause OTA and other mycotoxinsmay behighly soluble in the solvent commonly used for polyphenol extraction.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Karlton-Senaye, B.D., Yu, J. and Williams L.L. (2015). Morphological and molecular characterization of ochratoxin A producing black Aspergillus from grape pomace. Journal of Food Research, 4 (5): 39-50.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Yu, J., Smith, I., Karlton-Senaye, B., Mikiashvili, N., and Williams, L. (2018). Impacts of different drying methods on mold viability and ochratoxin A content of grape pomace. International Journal of Applied Agricultural Science. 4(2): 35-42. doi: 10.11648/j.ijaas.20180402.12.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Karlton-Senaye, B.D., Yu, J.*, & Williams L.L. Characterization of Ochratoxin A Producing Fungi from Grape Pomace. 2015 ASM General Meeting. May30-June 4, 2015, New Orleans, LA.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Smith, I., Junious, B., Williams, L.L., Yu, J. Ochratoxin A content in grape pomace of some grape cultivars grown in North Carolina. 2015 IFT Annual Meeting, July 11-14, 2015, Chicago, IL.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
N. Mikiashvili and J.Yu. Comparative study of two different methods for the determination of ochratoxin A in grape pomace (final paper number: 88). ACS 2016 Southeast Regional Meeting (SERMACS), October 23-26, 2016. Columbia, SC.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
J. Yu, I. Smith, B. D. Karlton-Senaye, and L.L. William. Effects of Different Drying Methods on Mold Viability and OTA Content of Grape Pomace. Poster presentation at 2017 NCAFCS Annual conference, March 2-4, 2017, Charlotte, NC.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
J. Yu, I. Smith and N. Mikiashvili, B. D. Karlton-Senaye, L.L. William, Effect of Different Drying Methods on Mold Viability and Ochratoxin Content of Grape Pomace. Oral Presentation. ARD 18th Biennial Research Symposium, April 1-5, 2017, Atlanta, Georgia.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
I. Smith and J. Yu. Effects of High Pressure Thermal Processing on Ochratoxin A content of Grape Pomace. Poster presentation at 2018 NCAFCS Annual conference, March 22-24, 2018, Wilmington, NC.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
I. Smith and J. Yu. Effects of high pressure thermal processing on ochratoxin A and polyphenols in grape pomace. 2018 ACS Southeast Regional Meeting (SERMACS), Oct.31-Nov.3, 2018, Augusta, Georgia.
- Type:
Other
Status:
Other
Year Published:
2017
Citation:
J. Yu, I. Smith and N. Mikiashvili (2017). Safety of grape derived products. The 16th Annual Small Farmer Field Day, June 15, 2017. NC A&T University Farm, Greensboro, NC
- Type:
Other
Status:
Other
Year Published:
2018
Citation:
J. Yu and I. Smith. Health Aspect and Safety Issue of Grape Derived Products. 2018 North Carolina Small Farms Week, NC A&T Alumni-Foundation Event Center. Greensboro, NC.
- Type:
Conference Papers and Presentations
Status:
Submitted
Year Published:
2019
Citation:
J. Yu and I. Smith. Detoxification of Ochratoxin A in Grape Pomace by Different Methods. 2019 ARD 19th Biennial Research Symposium, March 29-April 3, 2019, Jacksonville, FL.
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Progress 09/01/16 to 08/31/17
Outputs
Target Audience:The target audiences of this project include researchers and students in food science, viticulture and enology, food safety regulation officers, grape farmers and winery owners, health professional, food industry and consumers. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Two undergraduate students were involved in the project during this period. They were trained to conduct experiments toevaluatethe impact of differentdetoxification methodson polyphenol contents of grape pomace. One temporary research assistamt was fully trained to conduct the research about detoxification efficiency ofdifferent processing methods. How have the results been disseminated to communities of interest?The results were disseminated at the 2016 SERMACS, 2017NCAFCS Annual Conference, 1890 AGricultural Research Director Biennual Symposium, 2017 NC A&T Small Farms Weekand 2017 NC A &T Small Farmer Field Day. What do you plan to do during the next reporting period to accomplish the goals?During the next NCE period, the PI plans to (1) evaluate influence of thermal-pressure treatment of GP on the OTA and polyphenol contents,(2) evaluate the effectiveness of acidic treatment of GP on the OTA content, (3) test the effectiveness of enzymatic treatment of GP on OTA content.
Impacts
What was accomplished under these goals?
What has been accomplished: During this reporting period, we repeated some of the tasks in the objective 3 due to the possible cross contamination of samples used for OTA analysis in previous reporting period.Our main focus of this reporting period wasdetoxification of OTA contaminated grape pomace by some food processing methods. Baking and pressure cooking methods were tested. For baking, 5% of vacuum dried Muscadine Noble, Cabernet Franc and Chardonnay GP were added in the recipe of sugar cookie to form cookies dough which contains all purpose flour, sugar, butter and baking soda. the cookie dough was spiked with purified OTA to make sure the OTA content of dough was beyond the detection limit of analytical method.Dough and Cookie without GP and spiked OTA were used as controls. Baking was conducted at 350 °F (176 °C) for 20 minutes.The OTA were quantitatively extract from each sample using 70% methanol and determined by an ELISA method. Results were expressed as ng OTA per gram dry cookie. For pressure treatment, autoclave was used in the study. Wet GP samples from 7 grape variety were packed in autoclavable containers and autoclaved at 121°C for 20 min. After cool to room temperature, half of autoclaved samples were vacuum dried and ground into powder. Unautoclaved wet samples and vacuum dried samples were used as controls. The OTA were quantitatively extracted from each sample using 70% methanol and determined by an ELISA method. Results were expressed as ng OTA per gram dry sample. Outcomes/Findings: Compared the OTA contents of dough and cookies, it was found that baking of cookies did not reduce OTA content. Instead, the OTA contents of cookies samples were higher than those of dough for each type of grape pomace. The higher OTA contents in cookies compared to dough may be that baking increased the extractability of OTA due to the structural change of food matrix caused by baking. Therefore, regular baking method could not reduce OTA content in food products. Autoclave greatly reduced OTA content of grape pomace samples tested. The OTA reduction was 72-91% for wet GP samples and 74-88% for dry GP samples. Among 7 wet GP samples, 5 of them has OTA below 5 ug/kg after autoclave. Therefore, thermal-pressure treatment of GP could be an effective detoxification method to improve the safety of grape pomace.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Nona Mikiashvili and Jianmei Yu. Comparative study of two different methods for the determination of ochratoxin A in grape pomace. Abstract #: 88. ACS 2016 Southeast Regional Meeting (SERMACS), October 23-26, 2016. Columbia, SC.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
2. Jianmei Yu, Ivy Smith and Nona Mikiashvili, B. D. Karlton-Senaye, Leonard William, Effect of Different Drying Methods on Mold Viability and Ochratoxin A Content of Grape Pomace. ARD 18th Biennial Research Symposium, April 1-5, 2017, Atlanta, Georgia.
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Progress 09/01/15 to 08/31/16
Outputs
Target Audience:The target audience of this project include researchers and students in food science,viticulture andenology,food safety regulation officers,grape farmers and winery owners, health professional, food industry and consumers Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Twostudents were trained during this reporting period. Oneundergraduate student involved in drying of grape pomace by different methods and ochratoxin A extraction. The graduate student (MS) was trained toevaluate the effect of drying method on ochratoxin of grape pomace.The trained masters student is able totrain undergraduates to conduct OTA extraction and detection by ELISA method. How have the results been disseminated to communities of interest?The results were diseminated at the 2016 IFT meeting,2016 ACS Southeastern Regional Meeting and in the graduate seminar class FCS 760. What do you plan to do during the next reporting period to accomplish the goals?During the next reporting period, the PI plans to complete Objective 4 of the project: Evaluation of detoxification effects of selected food processing methods. The detoxification effects of baking, pressure cooking and ozonization will be evaluated.
Impacts
What was accomplished under these goals?
Impacts: Due to the potential health benefits of a high fiber and polyphenols, the utilization of GP as a food ingredient to develop healthy foods for the prevention of diet-related diseases has been a great interest of many researchers and scientists.However, the contaminationof grapes by molds resulted in OchratoxinA (OTA) presents a safety issue to the utilization of grape pomace.It isextremely important to accurately quantify the OTA level and to reduce the OTA level in order to ensure the safety of the GP usedas food and feed ingredients. The findings of this reporting period confirmed that a quick drying method such as freeze drying and vacuum drying couldefficiently inactivateOTA producing molds and spores and reduce OTA content in the pomace, thus improving the safety of grape pomace. The findings of this reporting period provide consumers and food processors a safe guide to preserve grape pomace for later use.This will contribute to the body of knowledge for food safety and make the value added utilization of grape pomace possible. The research findings also show that the OTA content of the same GP samples obtained by ELISA method and HPLC method were greatly different.Therefore, more study on the accurate quantification of OTA in GP is imperatively needed. What has been accomplished: During this reporting period, we evaluated the OTA concentration in fresh GP samples, repeated Task 3 and completed Task 4 of Objective 3. The reason of repetition isthe possibility of cross contamination of samples used for OTA analysis in the previous reporting period. Pomace samples of seven grape cultivars were dried by freeze drying, room temperature drying and vacuum drying. The freeze drying took 48 hr,vacuum drying took 24 hours, and room temperature drying took one week in a well ventilated lab to the achieve complete dryness. Part of each dry sample was ground into powder, the rest was separately into seeds and skins which then were ground into powder. The OTA of each sample was quantitatively extracted using 70% ethanol aqueous solution, then were quantified by ELISA method. Outcomes/Findings: OTA was detected in all fresh pomaces tested. The OTA contents of seven wet GP samples were in the range of 12.49-34.1 ng/g wet sample depending on the grape variety. Muscadine Noble and Sangiovese pomaces showed lowest and Chardonnay pomace showed highest OTA content. The order of OTA contents offresh pomace samples is: Chardonnay >Muscadine Carlos ≥ Cabernet Franc ≥ Merlot ≥ Cabernet Sauvignon> Sangiovese > Muscadine Noble.Drying method has significant effects on the viability of OTA producing molds and OTA content of GP. The OTA contents of dry GP samples were in the range of 25.46-169 ng/g dry sample. Freeze dried GP samples showed the lowest OTA content, while room temperature dried samples showed thehighest OTA content, although more molds were found in freeze dried pomace samples. Highest OTA levels were observed in Muscadine Carlos GPs regardless of drying methods. The OTA content in seeds were generally higher than that in skins of GP. The OTA contents in dry seeds and skins were 24.4-303.1 ng/g dry seeds and 23.7-317.9 ng/g dry skin, respectively. Muscadine Carlos skins and Chardonnay seeds showed much higher OTA content than all other samples.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Nona Mikiashvili, Ivy Smith, Leonard William and Jianmei Yu. Evaluating the Effect of Different Drying Methods on OTA Content of Grape Pomace. 2016 IFT Annual Meeting, July 2016, Chicago, IL
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Nona Mikiashvili, Ivy Smith and Jianmei Yu. Comparative study of two different methods for the determination of ochratoxin A in grape pomace. 2016 ACS Southeastern Regional Meeting, October 23-26 2016, Columbia, SC.
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Progress 09/01/14 to 08/31/15
Outputs
Target Audience:Target audience of this project include: Researchers and students, government agency, grape farmers and winery owners, health professional, food industry and consumers Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Two graduate students were trained during this reporting period. One Ph.D. student participate in the mold and fungus determination and one master student involved in drying of grape pomace by different methods and evaluate the effect of drying method on ochratoxincontent ingrape pomace. How have the results been disseminated to communities of interest?The results were disseminated to communities by publication and conference presentation. Bernice Dzifa Karlton-Senaye, Jianmei Yu, and Leonard Lamont Williams. (2015) Morphological and molecular characterization of ochratoxinAproducing black Aspergillusfrom grape pomace. Journal of Food Research, 4 (5): 39-50. Bernice D. Karlton-Senaye, Jianmei Yu & Leonard L. Williams. Characterization of Ochratoxin A Producing Fungi from Grape Pomace. 2015 ASM General Meeting. May30-June 4, 2015, New Orleans, LA. Ivy Smith, Britteny Junious, Leonard WilliamsJianmei Yu*. Ochratoxin A content in grape pomace of some grape cultivars grown in North Carolina. 2015 IFT Annual Meeting, July 11-14, 2015, Chicago, IL. What do you plan to do during the next reporting period to accomplish the goals?During next reporting period, I plan to complete Objective 4 of the project: Evaluation of detoxification effects of selected food processing methods. The detoxification effects of baking, pressure cooking and ozonization will be evaluated. Due to the relativelow level of ochratoxin content inmost ofgrape pomace samples tested, the ground GP will be spiked with OTA to the level that is at least 10-folders higher than the detectable level before it is mixed with other food ingredient.
Impacts
What was accomplished under these goals?
What has been accomplished: During this reporting period, the tasks listed under Objective 3 (Evaluating the Effectiveness of Different Drying Methods on Fungal Inactivation, OTA Content and Polyphenol Retention in GP) were completed. Pomace samples of seven grape cultivars were dried by freeze drying, room temperature drying and vacuum drying. Both freeze drying and vacuum drying took 24 hours, and room temperature drying took one week in a well ventilated lab to the achieve completely dry. The dry samples were ground into powder, and total fungal and yeast counts of samples were numerated by both direct plating and spread plating method. For OTA determination, seeds and skins were manually separated before grinding. The seeds and skins were ground into powder, and OTA were quantitatively extracted by 70% methanol aqueous solution. The OTA contents of samples were analyzed by ELISA assay and HPLC method. Outcomes/Findings: By ELISA method, regardless grape cultivar, seeds showed higher OTA content than skins with exception of Muscadine Carlos grape skin which showed OTA content of 59 ng/g dry skin powder. The OTA contents of most skin samples had OTA content lower or close to 10 ng/g dry powder. Vacuum and room temperature dried skin samples had OTA content lower or close to 10 ng/g dry powder, whereas, the freeze dried samples had OTA contents in the range of 10-20 ng/g dry powder. Vacuum dried seeds showed lowest OTA contents, while freeze dried seeds showed highest OTA content. In addition, the OTA in vacuum dried and room temperature Muscadine Noble seed samples were non detectable. For the same drying method, the OTA content of Chardonnay grape seeds was the highest among all seeds dried by the same methods. The OTA levels detected by HPLC methods were dramatically lower than that detected by ELISA method. But the trend is similar to that detected by ELISA method, that is vacuum dried samples showed lowest OTA levels, while freeze dried and room temperature dried samples showed higher OTA levels. The highest OTA levels were 12. 32 and 21.23 ng/g dry sample detected in the seeds of freeze dried and room temperature dried Chardonnay grape pomace, which is above the safe limit of OTA level set my EU (10ng/g). The OTA levels of GP samples dried by vacuum drying methods were all under 5ng/g dry sample which is well below the safe limit. Less mold population and relatively higher yeast population in the GP samples. Additionally, twenty-one (21) different Aspegillus species were isolated from the samples. GP from Chardonnay grape cultivar that was dried at room temperature showed the highest (12 CFU/ml) mold population and Franc and Sangiovese grape cultivars had the highest yeast population, which was too numerous to count. This is consistent with the results of OTA detection, that is, grape pomace samples with higher OTA contents had higher mold population. The high yeast count is because yeast is added to the crushed grape and juice to transform grape sugar into alcohol in fermentation process. The majority of yeast was retained in the pomace after the liquid was pressed following fermentation. In conclusion, the findings of this reporting period indicate that drying methods ofGP had great impact on the microbial load and ochratoxin content. Vacuum dried grape pomace samples had lowest OTA contents and mold counts comparing to the room temperature and freeze dried grape pomace samples. Due to the long drying period of room temperature drying method, the mold spores could germinate and produce toxins. Freeze drying could not destroy mold spores although it preserve polyphenol antioxidant in the pomace. Vacuum drying resulted in significant loss of polyphenols due to the heat sensitive property of most of the polyphenols, large amount of flavonoid retain in the pomace as showed in our previous study due to the high polyphenol content of grape pomace. To ensure the safety of grape pomace as a food ingredient, vacuum drying method is recommended. Impacts:Due to the potential health benefits of a high fiber and polyphenols GP has great potential to serve as a functional ingredient to develop healthy foods for the prevention of diet related diseases.However, due to the likely contamination by pathogenic fungi and mycotoxin,thesafety of the GP needs to be addressed.To ensure the safety of grape pomace, the pomace should be dried immediately after pressing by a quick drying method such as vacuum dryingto destroy molds and their spores. The findings of this reporting period provide consumers and food processors a safe guide to preserve grape pomace for later use.This will contribute to the body knowledge of food safety and make the value added utilization of grape pomace possible.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Bernice Dzifa Karlton-Senaye, Jianmei Yu, and Leonard Lamont Williams. (2015) Morphological and molecular characterization of Ochratoxin A producing black Aspergillusfrom grape pomace. Journal of Food Research, 4 (5): 39-50.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Ivy Smith, Britteny Junious, Leonard Williams Jianmei Yu. Ochratoxin A content in grape pomace of some grape cultivars grown in North Carolina. 2015 IFT Annual Meeting, July 11-14, 2015, Chicago, IL.
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Progress 09/01/13 to 08/31/14
Outputs
Target Audience: Target audiences include scientists from academia, government agency, grape farmers/winery owners, health professional, food industry, and consumers. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? One undergraduate and one graduate student were trained to conduct research on ochratoxinextraction, safe handlingand determination. One graduate student and one postdoctoral scholarwere trained to conduct mycology research of grape pomace. How have the results been disseminated to communities of interest? The results have not been disseminated yet. What do you plan to do during the next reporting period to accomplish the goals? During next reporting period,the project teamplans to complete the HPLC analysis of ochratoxin in the grape pomace extracts laid out inTask 3 of Objective 1 andTask 3 of objective 2: genetic confirmation of mycotoxin producing fungi isolated from grape pomace samples.The team will also complete tasks laid out inObjective 3 of the project including Task 1- Drying of grape pomace using different dehydration methods(freeze drying, room temperature drying, microwave drying and vacuum oven drying techniques), Task 2-Evaluating the effects of drying methods on the viability of OTA producing fungi, Task 3-Evaluating the effects of drying methods on the OTA level in GPs, and Task 4. Evaluating the effects of drying methods on the polyphenl contents of GPs.In addition,the project team will disseminate the findings in Professional Agricultural Worker's Conference (PAWC)in Tuskegee, AL, American Societyfor Microbilogy (ASM), Instituteof Food Technologiest (IFT) during the next reporting period.
Impacts
What was accomplished under these goals?
What has been accomplished: Tasks 1 and 2 of Objective 1, and Tasks 1 and 2 in objective 2 have been completed. Seven caultivars of grape pomace were collected from two North Carolina wineries. The grape pomace of each grape cultivarwas split into three portions.One portion was dried at room temperature,second portions were kept at -22ºC for fungi identification, and thethirs portion was keptat -22ºCfor objective 3 and 4. Ochratoxin levels in seven dried grape pomace samples were determined by ELISA method using the analytical kits purchased from Romer Laboratorary (Union, MO). The pH and water activity of wet pomace samples were determined, total population of mold in each sample was numerated, the population of yeast and mold in each pomace sample were determined using three different agars (DBRC, PDA and DG18),the morphologies of the isolated mold species were characterized. Outcomes/Findings:Ochratoxin Awas detected insome of thegrape pomace samples collected.The level ofochratoxin A in the pomace varied withgrape cultivars.The ochratoxin A levels in the pomace samplesof Chardonay, Cabernet Sauvignon,Sangiovese and Merlot grapeswere 159.99±36.99, 133.46±22.99, 134.00±23.08, and 20.06±3.87ng/g dry pomace, respectively,but no ochratoxin A was detected in the pomace samples of Muscadine Carlos, MuscadineNoble and Cabernet Franc grape.Majority of fungal contamination was from Aspergillus (87.5%). The highest population of mold (5.35±0.04 log CFUml-1) was detected in pomace made from Chardonnay wine grape, which also showed lowest water activity (0.979±0.01) and highest pH (3.93±0.01). No mold was detected in pomace obtained from Cabernet Franc, and Sangiovese wine grape.The results of ochratoxinmeasurements were in good agreement with that of fungi detections with exception of Sangivese pomace. More studies are needed to confirm these findings.The findings from this reporting period indicate that the pomaces of some grape cultivars are safe to be used as afood ingredient due to the lack of ochratoxin and toxin producing fungi, but some are not safe due to the contamination of pathogenic molds and presence of high ochratoxin content. Impacts: These findings provide consumers and food processors a safe guidewhen they select grape pomace as a health promoting food ingredient. This will contribute to the body of knowledgein thesafety of functional foods. The confirmation of the presence of mycotoxins and their producers will also alert small farmers to avoid harvesting molded grapes for wine making and to preserve pomace properly after fermentation to prevent mold growth if pomace will be used in human and animal foods.
Publications
- Type:
Conference Papers and Presentations
Status:
Under Review
Year Published:
2015
Citation:
1. Ochratoxin contents in the grape pomace of different wine grape cultivars grown in the North Carolina
2. Determination of Fungal Population and Aspergillus Species in Grape Pomace
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