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Session 6B: "Food Safety in Traditional and Non-Traditional Sources of Protein"
3:00pm - 5:00pm
Session Chair: Jitendra Paliwal
3:00pm - 3:20pm
Kinetics of heating inactivation of thermal resistant molds isolated from tropical fruit nectars
Amauri Rosenthal1, Elisa Helena Rocha Ferreira2, Lourdes Maria Pessoa Masson3, Maria de Lourdes Mendes de Souza1
1Embrapa, Brazil; 2Federal Rural University of Rio de Janeiro, Brazil; 3Federal Institute of Education, Science and Technology of Rio de Janeiro, Brazil
Microbiological safety of fruit nectars is commonly assessed regarding the total mesophilic counting, molds and yeasts population, salmonella detection, total and fecal coliforms and specific pathogenic strains such as Escherichia. coli O157:H7. However, thermal resistant molds may also be of concern considering their potential to produce mycotoxins such as patulin. This study aimed at characterizing the thermal inactivation kinetics of the most thermal resistant mold isolated from an aseptically packaged fruit nectars industrial line and its potential to produce patulin in different nectars (mango, pineapple and passion fruit). Ascoposores suspension of each mold isolate faced an increasing intensity thermal shocks in order to select the most thermal resistant one, which was further inoculated and activated in each nectar. The following kinetic parameters resulted from the study for mango, passion fruit and pineapple nectars, respectively: z values: 4.0ºC, 5.4ºC and 5.5ºC; F values: F105ºC < 1s, F98ºC = 135 min e F98ºC = 68 min. The commercial thermal treatment commonly applied to the mango nectar in the industrial line is 105ºC/30s, while to the pineapple and passion fruit nectars it is 98ºC/30s. As a conclusion, the treatment applied currently in mango nectar may be appropriate to provide a 5 log10 reduction on the most resistant mold, although the treatments presently applied to passion fruit and pineapple are not enough to provide the required population reduction. No patulin production was detected when the mold was inoculated directly in the three types of nectars.
3:20pm - 3:40pm
Microwave pasteurization for natural tamarind beverage
Arnold David Gonzalez-Monroy, Cesar Ozuna, Gabriela Rodriguez-Hernandez, Maria Elena Sosa-Morales
Universidad de Guanajuato, Mexico
In Mexico, the production of sodas and non-alcoholic beverages had an annual average growth of 7.5% in 2015. Drinks with real flavors are being positioned in the market. Microwaves treatments stand out among the emerging technologies in the treatment of foods, due to its high energy efficiency, sustainability and reduction of times and costs. Microwaves have been effective in retention of sensory properties of diverse thermo-labile drinks, such as coconut water and guava fruit nectar. The objective of this study is to develop a microwave treatment for pasteurization of a tamarind beverage. Batches of 480 g of the natural tamarind beverage (pH=2.73 and total soluble solids and 12.36°Bx) were packed in glass bottles and treated in a microwave conventional oven (490 W, 2450 MHz) until the target temperature of 90ºC. This temperature was held 12 s for enzyme inactivation. After the treatment, the natural tamarind beverages were closed and placed in a cold bath at 4°C for 10 min, then stored during 12 days at 4°C. Heating time was 280 s. Results showed an enzyme inactivation for microwave-treated samples for the target temperature (90°C). After the microwave pasteurization, there were not significant changes in pH, total soluble solids and sensory acceptance of samples in comparison with the untreated control sample (p>0.05), and neither in color (∆E* = 0.95).
3:40pm - 4:00pm
EFFECTS OF NON-THERMAL PROCESSING ON PROTEINS
Sai Kranthi Vanga, Vijaya Raghavan
McGill University, Canada
Non-thermal processing has been widely publicized as an alternative to thermal processing of plant-based foods. These include high pressure processing, ultrasound, application of electric fields, oscillating magnetic fields and irradiation. This is due to raising demand among consumers for “minimal processing” in foods. Research has shown that various non-thermal processing methods can achieve the required levels of pasteurization and further can modify the functional properties of various food components including proteins to improve the quality of food. Of the above mentioned methods, high pressure and ultrasound applications have already made it to a commercial scale followed by pulsed electric field in recent years being employed for pasteurization of fruit juices. However, there is a lack of knowledge on the effects of these processing methods on the food components on a microscopic scale, especially proteins which are one of the most volatile present in food. The tertiary and secondary structures of the protein govern the physico-chemical properties and in turn the overall quality of the food. Thus, it is vital for future research to emphasize on the importance of understanding the changes in protein structures due to various non-thermal processing being introduced into the food industries. The knowledge generated can be used to engineer proteins which can express desired physico-chemical properties through modifications in processing techniques. The direct implications would be in reduction of allergenicity in various food proteins, improved health benefits due to increased protein digestibility contributing to the overall health of the world.
4:00pm - 4:20pm
Membrane fractionation to produce canola protein-derived peptides with defined sizes and antoxidant properties
Rotimi Emmanuel Aluko, Monisola Adeola Alashi
University of Manitoba, Canada
Canola protein hydrolysates (CPHs) were prepared after protein digestion with each of the following five proteases: Alcalase, chymotrypsin, trypsin, pepsin and pancreatin. Each protein hydrolysatye was then passed sequentially through ultrafiltration membranes (1, 3, 5, and 10 kDa) to collect permeates with four distinct sizes (<1, 1-3, 3-5, and 5-10 kDa). The CPHs and their membrane fractions were analyzed for antioxidant properties using in vitro assays. The <1 kDa pancreatin peptide fraction at 10.1 ug/ml had the highest (p<0.05) effective concentration that scavenged 50% (EC50) of the ABTS+ radical. The CPHs and peptide fractions were very strong DPPH radical scavengers with most of the EC50 values being <1.0 mg/ml. In contrast the CPHs and peptide fractions had weak superoxide radical scavenging activity, except the <1 kDa pepsin peptide fraction that had a value of 51%. All the CPHs had very strong linoleic acid oxidation inhibition properties though the pepsin hydrolysate had the highest inhibitory effect. The oxygen radical absorbance capacity of Alcalase, chymotrypsin and pepsin hydrolysates was found to be better than that of glutathione (p < 0.05), a powerful cellular antioxidant. Overall, the shorter peptide chains had stronger antioxidant effects when compared to the longer peptides. Therefore, canola protein hydrolysis coupled with membrane ultrafiltration-assisted isolation of peptides with distinct size ranges could be effective processing tools to produce peptides with strong antioxidant properties and a good potential as preservatives to protect foods against oxidative stress-related spoilage.
4:20pm - 4:40pm
Microbiological safety of traditional fermented foods