Presentation Title

Assessment of Microbial Safety of Dehydrated Orange Pomace Powder

Faculty Mentor

Dr. Yao Olive Li, Dr. Wei-Jen Lin, Ms. Karoline Harrison

Start Date

17-11-2018 1:45 PM

End Date

17-11-2018 2:00 PM

Location

C161

Session

Oral 3

Type of Presentation

Oral Talk

Subject Area

biological_agricultural_sciences

Abstract

Orange pomace (OP) is a by-product of juicing process, including the peels, seeds, and pulps, which are abundant in phenolic compounds and dietary fiber that could be utilized as valued-added ingredients for functional food applications. Theoretically, dehydrated OP powder could be safely applied as a functional ingredient in food products that will undergo further thermal treatment (or a kill step) before consumption, however, a thorough assessment of its microbial safety is required before its commercial use in food product development. The objective of this study is to assess the microbial safety of the OP powder produced by a series of lab processing including pretreatment, drying, grinding and sieving steps, ultimately transforming the raw material (fresh OP collected from CPP Farm Store after the fresh-juicing process) to a shelf-stable powder ingredient. The TPC (total plate count), mold and yeast count, coliforms, E. coli, Listeria, Salmonella and Staphylococcus aureus were tested for the samples of starting material and the finished powder. The preliminary results showed variations of TPC and mold yeast counts and the presence of certain species batch by batch. Specifically, pre-shredding might cause cross-contamination if the cleaning and sanitizing of lab-utensils were not standardized. However, drying (160 oF for at least 6 hours) played a crucial role in killing most coliforms and Staphylococcus aureus. SMAC, BioChrome and CompactDry plates confirmed no Salmonella and E. coli present in dried OP powder, but Listeria might be a concern. All dried powder samples were free from Salmonella and E. coli O157: H7. TPC of OP dried powder varied from 2 log CFU/g to 4 log CFU/g and mold and yeast counts vary from 2 log CFU/g to 3.9 log CFU/g. Clearly, it is essential to establish standardized cleaning and sanitizing practices before and after drying process, esp. on the grinding and sieving operations. The ongoing research will verify the results after implementing the standardized cleaning and sanitizing methods.

Summary of research results to be presented

The preliminary results showed variations of TPC and mold yeast counts and the presence of certain species batch by batch, depending on the microbial condition of raw material. Also, pre-drying shredding might be a contamination step to introduce foreign pathogens when the cleaning and sanitizing of lab utensils were not standardized. However, drying (under 160oF for at least 6 hours) played a powerful role in killing most coliforms and Staphylococcus aureus from raw materials, due to thermal stress and significantly reduced water activity. SMAC, BioChrome and CompactDry plates confirmed no Salmonella and E. coli present, but Listeria might be a concern showing in several samples. All samples were free from Salmonella and E. coli O157:H7, while Staphylococcus aureus and coliforms were consistently in existence. TPC of OP dried powder varied from 2 log CFU/g to 4 log CFU/g batch by batch and mold and yeast counts vary from 2 log CFU/g to 3.9 log CFU/g. Clearly, the thorough cleaning and sanitizing of lab processing devices, specifically, on pre-shedding, post-drying grinding, and sieving, are essential to prevent cross-contamination. Based on these preliminary results, key unit operations with cross-contamination potentials are identified, and effective cleaning and sanitizing methods will be investigated and optimized. The comparison of all microbial indicators will be done when the standardized cleaning and sanitizing are to be implemented, to confirm the efficiency and improvement of the microbial quality of dehydrated orange pomace powder.

This document is currently not available here.

Share

COinS
 
Nov 17th, 1:45 PM Nov 17th, 2:00 PM

Assessment of Microbial Safety of Dehydrated Orange Pomace Powder

C161

Orange pomace (OP) is a by-product of juicing process, including the peels, seeds, and pulps, which are abundant in phenolic compounds and dietary fiber that could be utilized as valued-added ingredients for functional food applications. Theoretically, dehydrated OP powder could be safely applied as a functional ingredient in food products that will undergo further thermal treatment (or a kill step) before consumption, however, a thorough assessment of its microbial safety is required before its commercial use in food product development. The objective of this study is to assess the microbial safety of the OP powder produced by a series of lab processing including pretreatment, drying, grinding and sieving steps, ultimately transforming the raw material (fresh OP collected from CPP Farm Store after the fresh-juicing process) to a shelf-stable powder ingredient. The TPC (total plate count), mold and yeast count, coliforms, E. coli, Listeria, Salmonella and Staphylococcus aureus were tested for the samples of starting material and the finished powder. The preliminary results showed variations of TPC and mold yeast counts and the presence of certain species batch by batch. Specifically, pre-shredding might cause cross-contamination if the cleaning and sanitizing of lab-utensils were not standardized. However, drying (160 oF for at least 6 hours) played a crucial role in killing most coliforms and Staphylococcus aureus. SMAC, BioChrome and CompactDry plates confirmed no Salmonella and E. coli present in dried OP powder, but Listeria might be a concern. All dried powder samples were free from Salmonella and E. coli O157: H7. TPC of OP dried powder varied from 2 log CFU/g to 4 log CFU/g and mold and yeast counts vary from 2 log CFU/g to 3.9 log CFU/g. Clearly, it is essential to establish standardized cleaning and sanitizing practices before and after drying process, esp. on the grinding and sieving operations. The ongoing research will verify the results after implementing the standardized cleaning and sanitizing methods.