FDST 132- Practical Applications in Food Science — A Peer Review of Teaching Project: Benchmark Portfolio

The aim of this course portfolio was to assess improvement of students’ literature research skills and scientific writing after embedding communication lectures, activities and assignments in FDST 132 Practical Applications in Food Science. This is a terminal laboratory course for first year Food Science majors with basic science knowledge. The goal of the course is to allow students to put in practice some basic food science principles and work with their cohort. This portfolio outlines the changes made to this course, the rationale for embedding lectures and assessments in scientific communication. The specific skills and topics I aimed to teach students, and examples of the assessments and rubrics used to evaluate said skills. Through this portfolio I evaluate samples of student writing and reflect on their progressive improvement. I also reflect on the class modifications and what improvements could be made based on my own experience and students on the course and their attitudes towards the course content

Postharvest heat treatments to inhibit Penicillium digitatum growth and maintain quality of Mandarin (Citrus reticulata blanco)

Use of fungicides is a common practice as a postharvest treatment to control fruit decay. Nowadays, environment-friendly technologies, such as heat treatments, are viable replacements. This study evaluated the effects of post-harvest heat treatments (traditional and microwave-assisted) on mandarins intentionally inoculated with Penicillium digitatum. For the studied heat treatments, the target temperature was 50C, which was held for 2.5 min. After heating, mandarins were cooled and stored at 25C for 13 days. MW treatments effectively prevented mold growth during storage, while HW only delayed it. Control mandarins (without treatment) showed the highest significant weight loss. Neither thermal treatment nor storage affected fruit juice pH (p \u3e 0.05). Treated mandarins had a significantly lower vitamin C content than control fruits throughout storage, and all mandarins lost firmness by the 13th day (p \u3c 0.05). Control and MW-treated mandarins had lower citric acid content; however, they retained color, total soluble solids (TSS) and had a higher maturity index. While HW mandarins did not have changes in citric acid content, they had higher TSS, and lower maturity index. MW-assisted treatments were effective at inactivating molds and helped retain some nutritional and physical-chemical characteristics of mandarins. However, juice of MW-treated mandarins was not preferred by judges in the sensory tests, the juice was rated lower than that obtained from the other treatment. Postharvest heat treatments may constitute a helpful application to control mandarin’ fungal decay

AGEN/BSEN 112 Final project: Moving and Temperament of Cattle

Cattle movement and weather may affect the body temperature of cows which in turn affects their natural behavior and can influence their metabolism. Cattle take several days to resume their normal eating patterns after being overheated, and that can affect dairy production. This project was assigned to study the effect of temperament (calm vs excitable) and evaporative cooling on the body temperature of moving animals to optimize the environmental conditions around the cattle and consequently, dairy production. The project began with processing of a data set from Dr. Tami Brown-Brandl who was the client/adviser for the group. The data contained the body temperature of six heifer cows recorded every minute for 24 hours. During the recording period the cows were moved around from their pen, and either had water sprayed on them to aid in their cooling, or left dry. The cows were classified by their temperament as calm or excitable, depending on their reaction to the presence of humans. The results from the analysis showed movement of cattle had a consistent effect on their average body temperature. As time went on during the movement process, all cattle saw an increase in body temperature with excitable cows reaching a higher maximum temperature than calm cows. Unaided cooling (dry treatment) was also affected by temperament of the cows. Calm heifer’s temperature dropped 0.1 °C about every 2 hours, while excitable heifer’s temperature dropped 0.1 °C about every 6 hours. Evaporative cooling or wet treatments help the heifers shorten excess periods of elevated body temperature with no notable difference due to temperament. Based on the analysis it is recommended to treat all heifers with a wet treatment after movement in an effort to keep heifers calm and therefore easier to corral and handle

Inactivation of Salmonella enterica in black peppercorn by fluidization with hydrogen peroxide vapor

Salmonella is the most common bacterial pathogen associated with product recalls and outbreaks in spices. Spices are in the top three food categories for greatest number of recalls due to microbiological contamination. Current validated microbial reduction techniques for spices are tied to human health and environment concerns or negatively affect the quality characteristics of the spice which has led to the emerging of alternative technologies such as hydrogen peroxide vapor (HPV). hydrogen peroxide vapor treatment was conducted at two different temperatures (45°C and 60°C) and two dwell times (30 and 60 min). Microbial reduction and residual hydrogen peroxide were measured at three storage times: 0 h (immediately after treatment), 24 and 48 h post-treatment. The effect of HPV on the quality of whole black peppercorn was evaluated 48 h post-treatment based on changes in piperine content, total phenolics, antioxidant activity, total volatile compounds, and color. Reduction in Salmonella population ranged from 1.41–2.83 log CFU/g. Residual hydrogen peroxide of up to 500 ppm was still detected on samples after 48 h of storage. All quality parameters except for color remained unaffected between treated and untreated whole black peppercorn. The study highlights the need to explore further process design modifications before conclusions can be made on the efficacy of HPV treatment as a means for low-moisture foods pasteurization

INFLUENCE OF DIFFERENT FACTORS ON DESICCATION SURVIVAL AND THERMAL RESISTANCE OF SALMONELLA AND RADIOFREQUENCY PASTEURIZATION OF LOW-MOISTURE FOODS

Salmonella outbreaks associated with low-moisture food have become a food safety concern for the industry, government and public. Current sanitary practices have proven inefficient, intervention technologies need to be studied. Developing effective intervening treatments is challenging due to the limited information and understanding on Salmonella’s survival and inactivation kinetics in dry foods. The objective of this research was to better understand some extrinsic and intrinsic parameters affecting Salmonella’s thermal resistance in low-moisture foods, assess the effectiveness of Radiofrequency (RF) pasteurization for Salmonella in wheat flour, and evaluate Enterococcus faecium as a surrogate for RF inactivation of Salmonella. Five inoculation methodologies were evaluated on their effects over Salmonella’s population counts after inoculation, survival after equilibration to a low-water activity (aw) environment, and changes in thermal resistance in wheat flour. Water activity and food composition were explored with respect to their influence on the thermal resistance of Salmonella in almond meal (oil rich food) and organic wheat flour (carbohydrate rich food) using two types of cells. One cell had a Relative Humidity (R. H.) controlling solution to keep the food aw at 0.45 (TAC cells). The other cell allowed the foods’ aw to naturally elevate with temperature (TDT cells). Biofilm effects on short desiccation and thermal resistance of Salmonella, were studied by comparing the thermal resistance in wheat flour of 4 biofilm non-former strains, and 3 former strains after equilibration to 0.45 aw. Potential and effectiveness or RF as a pasteurization technology for low-moisture foods was also evaluated. Measurements of temperature uniformity during RF treatment of 3 low-moisture foods were made using an infrared camera. Finally, the effectiveness of RF treatments to pasteurize (achieve a 5 log reduction) of S. Enteritidis PT 30 and its surrogate E. faecium in wheat flour at different aw (0.25, 0.45, 0.65) was evaluated.Overall conclusions were that inoculation methodology, biofilm formation, food composition and aw can profoundly affect the thermal resistance of Salmonella and should be taken into account when designing new pasteurization treatments. And that RF can effectively pasteurize some low-moisture products like wheat flour

Desarrollo y evaluación de tratamientos con microondas de fresas

En el presente estudio se desarrollaron protocolos para tratamientos hidrotérmicos asistidos con microondas (MO) como tratamientos postcosecha potenciales para fresas. Los tratamientos consistieron en la inmersión de fresas (Fragaria x ananassa cv. Festival) en agua para posteriormente ser expuestas a microondas a una frecuencia de 2450 Hz por 3 min a 70% de la potencia (514.3 W) ó por 1 min 50 s a 90% de la potencia (762.8W) para alcanzar una temperatura promedio en el centro de la fruta de 43.8°C. Dichos protocolos fueron comparados con el tratamiento por inmersión de la fruta por 15 min en un baño de agua a 45°C y otro grupo de fresas sin tratar (testigo). Las frutas fueron almacenadas durante 9 días a 3°C y 90% de humedad relativa (HR). Las frutas tratadas con MO tuvieron la menor población de hongos y levaduras al final del estudio y la menor alteración en otros parámetros de calidad. Además se estudió la cinética de muerte microbiana de Botrytis cinerea, moho causante de una de las principales enfermedades de la fresa, en un sistema modelo que simula la composición de azúcares y ácidos de la fruta, así como en un puré de fresa. Se observó una mayor termorresistencia (mayores valores D), y mayor termosensibilidad (menor valor z) en el puré de fresa que en el sistema modelo

Postharvest heat treatments to inhibit Penicillium digitatum growth and maintain quality of Mandarin (Citrus reticulata blanco)

Use of fungicides is a common practice as a postharvest treatment to control fruit decay. Nowadays, environment-friendly technologies, such as heat treatments, are viable replacements. This study evaluated the effects of post-harvest heat treatments (traditional and microwave-assisted) on mandarins intentionally inoculated with Penicillium digitatum. For the studied heat treatments, the target temperature was 50C, which was held for 2.5 min. After heating, mandarins were cooled and stored at 25C for 13 days. MW treatments effectively prevented mold growth during storage, while HW only delayed it. Control mandarins (without treatment) showed the highest significant weight loss. Neither thermal treatment nor storage affected fruit juice pH (p \u3e 0.05). Treated mandarins had a significantly lower vitamin C content than control fruits throughout storage, and all mandarins lost firmness by the 13th day (p \u3c 0.05). Control and MW-treated mandarins had lower citric acid content; however, they retained color, total soluble solids (TSS) and had a higher maturity index. While HW mandarins did not have changes in citric acid content, they had higher TSS, and lower maturity index. MW-assisted treatments were effective at inactivating molds and helped retain some nutritional and physical-chemical characteristics of mandarins. However, juice of MW-treated mandarins was not preferred by judges in the sensory tests, the juice was rated lower than that obtained from the other treatment. Postharvest heat treatments may constitute a helpful application to control mandarin’ fungal decay

Radiofrequency Inactivation of Salmonella in Black Pepper and Dried Basil Leaves Using In-package Steaming

Radiofrequency (RF) heating has been extensively studied for pasteurizing low-moisture foods. Currently, bulk foods are treated with radiofrequency; potential cross-contamination may occur during packaging of pasteurized products. As an alternative, in-package RF processing was evaluated for Salmonella inactivation on black peppercorns and dried basil leaves and prevention of cross-contamination during storage postprocessing. In-package steaming refers to the process in which the samples were heated in a steam vent package to generate and retain steam during the treatment. This treatment achieved good heating uniformity which could be because of the circulation of steam within the package. One-way steam vent allowed the release of excess steam once a threshold pressure was achieved and later returned to its original position to seal the package, when the RF energy was removed. In-package RF steaming of black peppercorns and dried basil leaves for 135 s and 40 s, respectively, resulted in more than 5 log reduction of Salmonella. The steam vent remained stable posttreatment and properly sealed the package to protect the product from any external contamination. These results indicate that the use of steam vent could effectively pasteurize black peppercorns and dried basil leaves could be beneficial in preventing the potential cross-contamination postprocessing