Combination effect of 915 MHz microwave heating and carvacrol for inactivation of Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes in hot chili sauce

The synergistic bactericidal effect of simultaneous 222 nm krypton-chlorine excilamp and 307 nm UVB light treatment on sliced cheese and its mechanisms

In this study, we investigated the combined effect of 222 nm krypton-chlorine excilamp (EX) and 307 nm ultraviolet-B (UVB) light on the inactivation of Salmonella Typhimurium and Listeria monocytogenes on sliced cheese. The data confirmed that simultaneous exposure to EX and UVB irradiation for 80 s reduced S. Typhimurium and L. monocytogenes population by 3.50 and 3.20 log CFU/g, respectively, on sliced cheese. The synergistic cell count reductions in S. Typhimurium and L. monocytogenes in the combined treatment group were 0.88 and 0.59 log units, respectively. The inactivation mechanism underlying the EX and UVB combination treatment was evaluated using fluorescent staining. The combination of EX and UVB light induced the inactivation of reactive oxygen species (ROS) defense enzymes (superoxide dismutase) and synergistic ROS generation, resulting in synergistic lipid peroxidation and destruction of the cell membrane. There were no significant (P > 0.05) differences in the color, texture, or sensory attributes of sliced cheese between the combination treatment and control groups. These results demonstrate that combined treatment with EX and UVB light is a potential alternative strategy for inactivating foodborne pathogens in dairy products without affecting their quality.

Effect of Conventional Preservatives and Essential Oils on the Survival and Growth of Escherichia coli in Vegetable Sauces: A Comparative Study

Essential oils have gained attention as natural alternatives to chemical preservatives in food preservation. However, more information is needed regarding consumer acceptance of essential oils in actual food products. This study aimed to compare the effects of conventional preservatives, heat treatment, and essential oils derived from thyme, oregano, and lemongrass on the survival and growth of pathogenic Escherichia coli in vegetable sauces. The results demonstrated a gradual decrease in pathogen numbers over time, even in untreated samples. On the fifth day of storage, heat treatment, sodium chloride, and acidification using citric acid (pH 3.2) exhibited reductions of 4.4 to 5.3 log CFU/g compared to the untreated control. Among the essential oils tested, lemongrass essential oil at a concentration of 512 mg/kg demonstrated the most remarkable effectiveness, resulting in a reduction of 1.9 log CFU/g compared to the control. Fifteen days after treatment, the control samples exhibited a contamination rate of 6.2 log CFU/g, while E. coli numbers in treated samples with heat, sodium chloride, citric acid (pH 3.2), and lemongrass essential oil (512 mg/kg) were below the detection limits. Additionally, sensory evaluation was conducted to assess the acceptability of the treated samples. The findings provide valuable insights into the potential utilisation of essential oils as natural preservatives in vegetable sauces and their impact on consumer acceptance.

Experimental investigation of different-shaped microwave-heated potatoes: thermal and quality characteristics analysis for food preservation

Food materials are consumed for nutritional purposes in the form of fruits, vegetables, plants, and meat. These contain proteins, carbohydrates, and other useful nutritional compounds and these processed foods are a rich source of nutrition. The demand and supply of hygienic food for a particular population is possible only by food preservation. It can be done by various methods such as drying, freezing, chilling, chemical preservation, and pasteurization. Drying is a method of food preservation and it can be done by solar drying, microwave heating, vacuum drying, and some other methods. Microwave heating is a fast-drying method. It utilizes electrical energy to generate heat energy. The domestic microwave oven is not harmful but a commercial-level oven may be little bit harmful, when operated on high frequency. Potato is used as a sample material with different shapes such as slab, cylindrical, and spherical. The microwave oven has been operated at four different microwave powers such as 100 W, 300 W, 600 W, and 800 W. Slab-shaped (30 °C), cylindrical-shaped (31.5 °C), and spherical-shaped (30.5 °C) food materials achieved maximum temperatures of 83.9 °C, 110.6 °C, and 146.1 °C respectively. The temperature variations and drying characteristics of the food samples have been monitored. An oven has achieved maximum drying efficiency of 25.65% with a slab-shaped sample. For the detection of the cracks and chemical compositions in the food samples, SEM with EDS analysis has been performed. Economic analysis of microwave oven has also been done and payback period has been found as 3.27 years.

Influence of soil quality factors on capsaicin biosynthesis, pungency, yield, and produce quality of chili: An insight on Csy1, Pun1, and Pun12 signaling responses

Hotness or pungency is the major trait of genetically diverse and economically valuable chili (Capsicum sp.) cultivars. However, little is known about the influence of soil characteristics on genetic regulation of pungency vis-à-vis capsaicin formation in endemic chilies. Hence, the present work was conducted by growing two endemic chili cultivars in two types (alluvial and lateritic) of soil. Capsaicin content, pungency, and capsaicin synthase activity were significantly greater in chilies grown in alluvial soil than in lateritic soil. Correspondingly, Csy1, the gene that encodes capsaicin synthase, was significantly upregulated in alluvial soil grown plants. Interestingly, upregulation of Pun1, the gene responsible for capsaicin accumulation in fruits, was more in lateritic soil than in alluvial soil; but pungency was inhibited in lateritic soil by the overexpression of Pun1², a recessive allele of Pun1 locus. Statistical analyses revealed that high organic C, microbial activity, and NPK status in alluvial soil were responsible for high pungency, capsaicin synthase activity, capsaicin accumulation, and suppression of Pun1². Fruit yield, dry matter, crude protein, titratable acidity, and soluble solids were also significantly high in chilies grown in alluvial soil. Therefore, we postulate that soil quality attributes play vital roles in genetic regulation of pungency, capsaicin biosynthesis, fruit yield, and produce quality of endemic chili cultivars.