Lori F. Pivarnik

Hydrolytic and Transgalactosylic Activities of Commercial β-Galactosidase (Lactase) in Food Processing

Publisher Summary This chapter focuses on hydrolytic and transgalactosylic activities of commercial β -galactosidase (lactase) in food processing. Food enzyme technology is the use of commercial sources of these biocatalytic compounds in the processing of food. The enzymes used for this purpose may be derived from plant, animal, or microbial sources, but generally do not require much refining to reach food-grade status. The functionality and stability of commercial and potential commercial sources of β -galactosidases for hydrolytic processes must be improved to use the enzymes under conditions that are safe from microbial contamination. To realize this goal, research is required to develop lactases that are resistant to normal processing temperatures, such as that of pasteurization. The continuing development of new microencapsulation technologies could result in a variety of heat-resistant enzymes and more research is needed. The products formed, which are addressed in this chapter, vary with the starting substrates and microbial source of the enzyme. The complete analysis of the oligosaccharides formed requires separation procedures, such as paper chromatography (PC), column chromatography, thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), and gas-liquid chromatography (GLC). In addition, the identification of new products and the glycosidic linkages formed by the enzyme requires techniques such as mass spectroscopy (MS) and nuclear magnetic resonance (NMR).

Quality Assessment of Filtered Smoked Yellowfin Tuna ( Thunnus albacares ) Steaks

UNLABELLED Filtered smoke (FS) has been used to preserve taste, texture, and/or color in tuna and other fish species. This treatment is particularly important in color preservation during frozen storage. The objective of this study was to compare changes in the quality profiles of FS-treated and untreated (UT) yellowfin tuna (Thunnus albacares) steaks stored in 3 ways: room temperature (21 to 22 °C), refrigerated (4 to 5 °C), and iced (0 °C). FS and UT steaks were processed from the same lot of fish and analyzed for chemical, microbiological, lipid oxidation, color, and sensory profiles. Similar trends were seen for microbial proliferation and accumulation of apparent ammonia and total volatile base nitrogen (TVB-N) during the storage temperatures evaluated. Notable exception in quality profile was found in lipid oxidation which was, as expected, lower for treated samples at all storage temperatures for TBARS (P < 0.05) and lower or significantly (P < 0.05) lower for POV values. FS increased the initial redness value significantly (P < 0.05). Unlike UT product, there was no loss of color value concomitant with quality changes for FS-treated tuna for all storage temperatures evaluated. PRACTICAL APPLICATION The overall goal of this project was to evaluate filtered smoked tuna steaks as to the impact on the overall quality profile. As a color-stabilizing technology, it could mask deteriorating quality.

Effect of high hydrostatic pressure on four genotypes of F‐specific RNA bacteriophages

Aims:  The pressure responses of four genotypes of F‐specific RNA bacteriophages, f2, GA, Qβ and SP, were evaluated with respect to pressure magnitude, treatment temperature and suspending medium.

Quality Assessment of Commercially Processed Carbon Monoxide‐Treated Tilapia Fillets

Carbon monoxide (CO) has been used to stabilize the color of fish muscle during frozen storage and distribution. This study compared changes in the quality profiles of CO-treated and untreated (UT) tilapia fillets stored at 21 to 22 °C (room temperature), 4 to 5 °C (refrigerated), and 0 °C (iced). Samples (n = 3) were analyzed at different time intervals for chemical, lipid oxidation, microbiological, color, and expert sensory profiles. CO samples contained greater (P < 0.05) apparent ammonia and total volatile base nitrogen (TVB-N) at day 0, with greater (P < 0.05) TVB-N throughout refrigerated and iced storage. At time 0, peroxide values (POV) and thiobarbituric-acid-reactive substances were lower (P < 0.05) for CO samples and continued to have lower trends throughout all storage temperatures. Microbiological analysis at time 0 did not show any differences between UT and CO samples. Redness (a*) color values were greater (P < 0.05) in CO tilapia at time 0; however, treated product showed a more rapid decline in a* throughout all storage temperatures. While expert sensory evaluation showed no statistical differences between UT and CO tilapia at time 0, CO product failed sensory assessment sooner than UT product when stored refrigerated and in ice.

Pressure Inactivation of Enteric Viruses in a Seafood Salad-Like Product

High pressure processing (HPP) is a nonthermal processing technology that can inactivate foodborne viruses. This study assessed the protective effects of food components on virus inactivation by HPP in a seafood salad model. Virus-inoculated seafood samples (cod, shrimp, tuna, and clams) with or without mayonnaise were pressure-treated at 5°C. The seafood salad provided a protective effect on HPP inactivation compared to cell culture medium. Inactivation in seafood salad varied greatly due to the complex nature of the food matrix. When seafood salad ingredients were isolated, mayonnaise alone had a 2.0-log10 PFU/g protective effect for all viruses, unlike albumin, which did not affect virus inactivation, providing some insight into the roles individual ingredients may play on HPP inactivation of viruses in foods.

Assessing Knowledge and Attitudes of U.S. Healthcare Providers about Benefits and Risks of Consuming Seafood

An online needs assessment survey of healthcare providers was developed and implemented to determine knowledge and attitudes about the benefits and risks of consuming seafood along with how this might impact patient/clientele counseling. Only 6 of the 45 knowledge items queried (13%) met the 80% subject mastery or proficiency with a total knowledge score of 56 ± 18%. Based on this survey, it was found that healthcare providers were less than proficient regarding all knowledge areas for seafood. Understanding of seafood safety and contaminants was low. In addition, while the majority (76%) of healthcare respondents knew the correct recommendation for seafood meals per week, they failed to identify the groups that were targeted by the Food and Drug Administration/Environmental Protection Agency (FDA/EPA) advisory about seafood and mercury and therefore could be providing inaccurate information. Attitudinal responses for 18 items resulted in an overall average score of 3.28 ± 0.47 meaning slightly agree (based on a 5-point Likert scale strongly disagree—strongly agree). While trends showed that it was important to the respondents to provide accurate information (3.78 ± 1.06) about seafood to their patients, they felt more comfortable recommending that their patients follow government advice (3.52 ± 0.91) about both seafood safety and which seafood to eat over other sources. Combined with a low knowledge base, attitudinal responses indicate that there could be a barrier to both outreach education to these healthcare providers and to their patient counseling regarding seafood consumption. Results also showed that a combination of online, science-based, easy to access information with the capability to provide brochure-formatted information would appear to be the best way to communicate seafood safety, nutrition, and health information.

Development and Pilot Testing of a Food Safety Curriculum for Managers and Staff of Residential Childcare Institutions (RCCIs).

Food safety training materials, targeted for residential childcare institution (RCCI) staff of facilities of 20 residents or less, were developed, piloted, and evaluated. The goal was to assist in the implementation of a Hazard Analysis Critical Control Points (HACCP)-based food safety plan as required by Food and Nutrition Service/United States Department of Agriculture. RCCI staff and instructor training manuals, Food Safety Basics: Food Safety Education for RCCIs was developed and pilot tested in RCCIs in both Rhode Island and Massachusetts. The program was evaluated by participants and pre-/posttraining onsite inspector and microbial assessments. The core curriculum contained 3 modules and corresponding activities: Module 1: cause, prevention, and strategies to reduce foodborne illness; Module 2: components of a HACCP-based food safety plan and standard operating procedures; and Module 3: actual food safety plan development, including instructions for implementation and corresponding monitoring procedures required. There were 50 to 82 RCCI staff members that attended 2 or 3 modules. Participants rated the modules 4.5 ± 0.4, 4.3 ± 0.4, and 4.4 ± 0.4 out of 5-point Likert scale (1 = strongly disagree, 5 = strongly agree) for teaching modules 1, 2, and 3, respectively. The evaluations assessed their understanding of key topic areas taught. Onsite inspections showed improvement in many critical food safety issues. Some deficiencies still appeared to be problematic, such as refrigerator temperature monitoring and issues with storage and cross-contamination.

Antimicrobial Activity of 1% Cetylpyridinium Chloride Against Listeria spp. on Fish

Cetylpyridinium chloride (CPC) was evaluated as an antimicrobial against Listeria monocytogenes (LM) and Listeria innocua (LI) on fish. LI and LM showed the same reduction profile and the same minimum inhibitory and bactericidal concentrations. When CPC was applied to a diced fish matrix, reductions of 3.17–3.26 and 3.07–3.19 log were determined for LI and LM, respectively. Antimicrobial activity of CPC against LI resulted in initial reductions of 2.8–3.1 log in fresh fish fillets, 0.9–1.1 log in smoked fish fillets, and 3.2–3.4 log on fish skin. Effectiveness of CPC against total plate counts on fish skin showed reductions of 2.4–2.9 log.

Knowledge and Attitudes of Produce and Seafood Processors and Food Safety Educators Regarding Nonthermal Processes.

A needs assessment survey was designed and administered to measure knowledge of and attitudes toward food safety impacts of nonthermal processing technologies of shellfish and produce industry personnel and extension educators. An online survey was sent via e-mail notification with the survey link through professional listserves. The survey evaluated background information, knowledge, attitude, and training needs. A variety of response formats was used. Knowledge/attitude responses were analyzed using descriptive statistics, 1-way ANOVA and t-tests using SPSS software and reported at P 0.9. There were no differences in attitudes and knowledge between the 2 industry groups. The total attitude score, based on a 5-point Likert scale (1 = strongly disagree, 5 = strongly agree), of the produce and shellfish industry and educator respondents toward nonthermal processing technologies was 3.6 ± 0.4, 3.4 ± 0.5, and 3.6 ± 0.4, respectively. Respondents slightly indifferent attitude may reflect low knowledge regarding the impact of nonthermal processing technologies on food safety and quality. Both groups indicated a desire for information and/or training. For both industry and educators, common preferred formats for outreach resources were printed materials, Internet/web-based materials, and PowerPoint. Educators identified barriers as equipment cost, lack of information, and lack of product validation. While the majority of the respondents were aware of nonthermal processing, they were not knowledgeable, indicating a need for education and outreach in nonthermal processing methods to both shellfish/produce industry and food safety educators.