Predicting the Quality of Pasteurized Vegetables Using Kinetic Models: A Review

A resurgence in interest examining thermal pasteurization technologies has been driven by demands for “cleaner” labeling and the need of organic and natural foods markets for suitable preventive measures to impede microbial growth and extend shelf life of minimally processed foods and ready-to-eat foods with a concomitant reduction in the use of chemical preservatives. This review describes the effects of thermal pasteurization on vegetable quality attributes including altering flavor and texture to improve consumer acceptability, stabilizing color, improving digestibility, palatability and retaining bioavailability of important nutrients, and bioactive compounds. Here, we provide kinetic parameters for inactivation of viral and bacterial pathogens and their surrogates and marker enzymes used to monitor process effectiveness in a variety of plant food items. Data on thermal processing protocols leading to higher retention and bioactivity are also presented. Thermal inactivation of foodborne viruses and pathogenic bacteria, specifically at lower pasteurization temperatures or via new technologies such as dielectric heating, can lead to greater retention of “fresh-like” properties

Manipulation of photoperiod in growth factors of beluga sturgeon Huso huso

The beluga sturgeon is considered as the most important species for caviar production. This study aimed to evaluate effects of photoperiod manipulation on growth factors of beluga sturgeon. The six photoperiod regimes (light: dark cycle) including natural photoperiod (control), 24L : 0D, 16L : 8D, 12L : 12D, 8L : 16D and 0L : 24D with the three replicates. The treatment 5 (8L: 16D) gained the greatest final weight (2194.4 g) after 73 rearing days and besides, the treatments 4, 3 and 1 (12L : 12D, 16L : 8D, and Control) can be considered as the good photoperiod regimes for beluga sturgeon. The continuous light (24L : 0D) and continuous dark (0L : 24D) significantly (P < 0.05) reduced the final weight of fish to 1804.2 g and 1976.1 g, respectively. Regulated photoperiod significantly improve growth rate and food conversion ratio of beluga sturgeon

Growth, biochemical response and liver health of juvenile barramundi (Lates calcarifer) fed fermented and nonfermented tuna hydrolysate as fishmeal protein replacement ingredients

© 2018 Siddik et al. Conventional aquaculture feed materials available in Australia are expensive, which has prompted the search for alternatives that would be cost-effective and locally available. The present study was undertaken in order to maximize the use of a tuna hydrolysate (TH), which was produced locally from the tuna-processing discards. The growth performance, biochemical status, antioxidant capacity and liver health of juvenile barramundi (Lates calcarifer) were assessed. Two series of isonitrogenous and isocaloric diets labelled as TH50, TH75(non-fermented tuna hydrolysate) and FTH50, FTH75(fermented tuna hydrolysate) were formulated to replace FM at 50% and 75%, respectively. A basal diet without the TH supplementation was used as a control. The experimental diets were fed to the triplicate groups of fish three times a day for 56 days. The results of the experiment revealed that fish fed on both fermented and non-fermented TH-containing diets significantly reduced (p < 0:05) the final body weight, weight gain and specific growth rate compared to the control. The highest apparent digestibility coefficients for dry matter, protein and lipid were obtained in the control group, and decreased with the increasing level of TH in the diets. However, the whole-body proximate compositions and the blood biochemical indices of fish were not affected by the TH inclusion in the diets. The fish fed on TH diets of TH50, FTH50and TH75exhibited reduced (p < 0:05) glutathione peroxidase (GPx) activity compared to the control; whereas the FTH75exhibited no difference with the control. The excessive inclusion of TH in the diets of TH75and FTH75resulted in cytoplasmic vacuolization, with an increased amount of lipid accumulation, and necrosis in the liver tissue. These results indicated that the replacement of the FM protein with TH at 50% and 75% inclusion levels negatively affected the growth performance, feed utilization, and digestibility in juvenile barramundi; and it also increased the potential risk of hepatic failure in the fish. Further investigation is, therefore, required in order to optimize the TH levels in the fish diets which would be suitable for the growth of fish, as well as for maintaining the enhanced biochemical response in juvenile barramundi

Dietary tuna hydrolysate modulates growth performance, immune response, intestinal morphology and resistance to Streptococcus iniae in juvenile barramundi, Lates calcarifer

This study investigated the effects of tuna hydrolysate (TH) inclusion in fishmeal (FM) based diets on the growth performance, innate immune response, intestinal health and resistance to Streptococcus iniae infection in juvenile barramundi, Lates calcarifer. Five isonitrogenous and isoenergetic experimental diets were prepared with TH, replacing FM at levels of 0% (control) 5%, 10%, 15% and 20%, and fed fish to apparent satiation three times daily for 8 weeks. The results showed that fish fed diets containing 5% and 10% TH had significantly higher final body weight and specific growth rate than the control. A significant reduction in blood glucose was found in fish fed 10%, 15% and 20% TH compared to those in the control whereas none of the other measured blood and serum indices were influenced by TH inclusion. Histological observation revealed a significant enhancement in goblet cell numbers in distal intestine of fish fed 5 to 10% TH in the diet. Moreover, fish fed 10% TH exhibited the highest resistance against Streptococcus iniae infection during a bacterial challenge trial. These findings therefore demonstrate that the replacement of 5 to 10% FM with TH improves growth, immune response, intestinal health and disease resistance in juvenile barramundi

KINETIC STUDY OF QUALITY DEGRADATION OF ATLANTIC SALMON (SALMO SALAR) MUSCLE DURING THERMAL PROCESSING AND IN RESPONSE TO ELECTROLYZED WATER AND MILD-THERMAL PROCESSING COMBINATIONS

Thermal processing is used in food industry to control the Listeria monocytogenes but unfortunately, causes food quality degradation. To find the optimum processing conditions, a kinetic study is required to study quality changes in foods. Combining thermal processing with non-thermal processing can also decrease the effect of thermal processing on food quality. Overall objective of this study was to optimize the thermal processing of Atlantic salmon (Salmo salar) through a kinetics study, and to investigate the effect of different electrolyzed water (EO) solutions, including acidic electrolyzed water (AEW) and neutral electrolyzed water (NEW), alone and in combination, with mild thermal processing (50, 55, 60, 65 °C) at different exposure times on the inactivation of L. monocytogenes in Atlantic salmon fillets.Findings indicate that cook loss, area shrinkage, and protein denaturation parameters were best fitted to a first-order reaction and color parameters followed zero-order kinetics. Fourier transform infrared spectroscopy (FTIR) showed that increasing heating time and temperature reduced the α-helix peak (protein denaturation) and increased the β-sheet peak intensity (protein aggregation). The protein denaturation activation energy from Differential Scanning Calorimetry (DSC) was 301 kJ/mol.The results of the study show that NEW has stronger antimicrobial properties compared to AEW which caused 5.6 log10 CFU/g reduction in samples treated 65 °C for 10 min. The salmon muscle secondary protein structure showed that NEW had less impact on the protein compared to AEW, as shown by a PCA model based upon FTIR spectral changes in the protein spectral region. In addition, the FTIR spectra for L. monocytogenes showed that the NEW and AEW had different impacts on the bacterial cell wall; this might be due to the form of available chlorine in NEW and AEW and to the difference in pH.In conclusion, FTIR, and dielectric properties were able to show the protein denaturation and aggregation which were consistent with DSC results. In addition, the NEW had higher antimicrobial properties compared to AEW with significantly less impact on protein secondary structure. Also, the efficacy of EO waters increased by increasing the process temperature

Prevalence of Microplastics in the Eastern Oyster <i>Crassostrea virginica</i> in the Chesapeake Bay: The Impact of Different Digestion Methods on Microplastic Properties

This study aimed to determine the microplastic prevalence in eastern oysters (C. virginica) in three sites in the Chesapeake Bay in Virginia and optimize the digestion methods. The digestion results illustrate that the lowest recovery rate and digestion recovery were related to enzymatic, enzymatic + hydrogen peroxide (H2O2), and HCl 5% treatments, while the highest digestion recovery and recovery rate were observed in H2O2 and basic (KOH) treatments. Nitric acid digestion resulted in satisfying digestion recovery (100%), while no blue polyethylene microplastics were observed due to the poor recovery rate. In addition, nitric acid altered the color, changed the Raman spectrum intensity, and melted polypropylene (PP) and polyethylene terephthalate (PET). In order to determine the number of microplastics, 144 oysters with an approximately similar size and weight from three sites, including the James River, York River, and Eastern Shore, were evaluated. Fragments were the most abundant microplastics among the different microplastics, followed by fibers and beads, in the three sites. A significantly higher number of fragments were found in the James River, probably due to the greater amount of human activities. The number of microplastics per gram of oyster tissue was higher in the James River, with 7 MPs/g tissue, than in the York River and Eastern Shore, with 6.7 and 5.6 MPs/g tissue