Food Science and Technology International最新文献

Ohmic heating is an emerging direct thermal technology, which uses electricity to heat food products volumetrically. Ohmic heating provides thermal and non-thermal effects like electropermeabilization to inactivate microorganisms. In this study, ohmic heating was used to inactivate Byssochlamys fulva in tomato juice. The main and interaction effects of initial pH (3.5 and 4.5) and voltage gradient (15 and 20 V/cm) were investigated on mold inactivation during ohmic heating at 88, 93, and 98 °C for 20, 10 and 5 min, respectively. The pH, acidity, total soluble solids, and D_value were compared. The results showed that pH and voltage gradient had significant effects on D_value and Z_value (p < 0.05). In order to model the survival behavior of Byssochlamys fulva, due to the nonlinearity of the curves, Weibull model gave more accurate estimation compared to classical first-order model.

The work aims to optimize the process of cold plasma for fresh-cut kiwifruit. The effects of discharge times, treatment voltages, and slice thickness as well as the interaction between them were investigated. Factor analysis was used to screen out the characteristic indices of fresh-cut kiwifruit. Design-Expert software was used to design three-factor response surface tests and find the optimal parameters. The results revealed that the quality indices of fresh-cut kiwifruit were the color difference, brittleness, and solid-acid ratio, the established binomial regression equations were significant (P < 0.05). At the optimal level: 26 kV treatment voltage, 120 s discharge times, and 10 mm slice thickness, the optimized test values for the color difference, brittleness, solid-acid ratio and decreased logarithm value of total plate count were 2.25, 128.96 g·s, 18.03 and 2.30 lg(CFU·g^-1), respectively. Cold plasma could significantly improve the inactivation of bacteria in fresh-cut kiwifruit.

This study delves into an exploration of the antimicrobial and antibiofilm properties of the essential oils (EOs) of cinnamon, garlic, and onion on Salmonella Enteritidis. Firstly, disc diffusion and minimum inhibitory concentration (MIC) techniques were employed to assess the antibacterial activity of the EOs. Additionally, the study explored the effect of these EOs on both initial cell attachment and 24 h-preformed biofilms. The crystal violet assay was implemented to evaluate biofilm biomass. The findings revealed that cinnamon EO exhibited the highest anti-biofilm activity. Furthermore, initial cell attachment inhibition at MIC ranged between 50 and 65% for the three oils, while inhibition rates on preformed structures were lower than 40% for all EOs at this MIC concentration. The study also found that the effects of these oils were dosage- and time-dependent (p < 0.05), thereby urging the adoption of these natural extracts as effective strategies for combating Salmonella biofilms.

The purpose of this study was to ascertain how probiotic culture affected the physicochemical, textural, and microbiological characteristics of probiotic soy cheese during storage. Moreover, the release of bioactive peptides during fermentation and storage was examined. Each cheese sample was made from one of the probiotic cultures of Lactobacillus acidophilus, Lacticaseibacillus casei, and Bifidobacterium lactis. Peptide extracts were prepared from these samples and fractionated using reversed-phase high-performance liquid chromatography. The sample containing L. acidophilus had the highest dry matter and hardness. The samples with L. acidophilus and B. lactis, respectively, had the highest concentrations of lactic acid and acetic acid. During storage the acidity, dry matter, lactic acid, acetic acid, and hardness of the samples increased but the pH, springiness, and cohesiveness reduced (P < 0.05). All samples had a probiotic count greater than 10⁷ CFU/g at the end of the storage. Antibacterial and antioxidant properties were found in the peptide fractions that were extracted from the samples. T2F4 (the fourth fraction separated from L. casei sample) had the greatest functional properties. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed the existence of peptide with a molecular mass of 5-10 kDa. Therefore, produced cheese is regarded as a suitable source of potentially bioactive peptides which can be utilized in food industry.

This study aimed to assess the potential use of grains (amaranth, millet, and quinoa) as immobilizing matrices on the metabolic activity of Lactiplantibacillus plantarum and evaluate the viability of the probiotic immobilized in millet during simulated oro-gastrointestinal digestion (OGI) and storage. Firstly, different grains, sterilization and immobilization times were assessed. Secondly, Lp. plantarum was immobilized in millet and its viability and metabolic activity were assessed during non-refrigerated long-term storage and OGI. Metabolic activity was higher with 15 min. of grain sterilization and 72 h of immobilization. Lp. plantarum in millet showed the highest count. Millet grains were able to maintain the high population (>7 log CFU/g) and the metabolic activity of Lp. plantarum during up to 150 d of storage and conferred a protective effect on entrapped probiotic cells during OGI. Millet is a promising immobilizing matrix for the addition of probiotics in dry food products.

Resistant maltodextrin (RMD) was added at increasing concentrations (0%, 2.5%, 5% and 7.5%) before pasteurisation to orange juice to analyse its potential protective effect on the health-related bioactive compounds of pasteurised orange juice throughout its storage time. Samples were characterised in terms of basic physico-chemical properties and bioactive compounds at the beginning of the storage. Higher concentrations of RMD proved to better preserve the bioactive compounds of orange juice, thus obtaining a higher antioxidant capacity (AC). Stability of all samples was determined by measuring the same parameters at days 0, 15, 45, 75, 105, 136 and 170 of storage. °Brix and pH were very stable in all samples along storage, while all bioactive compouds had negative variations. However, RMD addition slightly improved ascorbic acid, vitamin C, total phenols, and total carotenoids retention, improving then its AC. This effect was greater in the 5% RMD-added samples. All bioactive compounds showed a positive Pearson's correlation coefficient with AC. Colour variations were also measured at days 105 and 170. All samples had a positive variation of all colour parameters, being this clearer at day 170. This work enlights the potential functionality of RMD to better preserve the health-related compounds of pasteurised orange juice.

Radio frequency (RF) heating has been studied to inactivate bacteria in some powder foods. In this study, a 6 kW, 27.12 MHz RF system was used to pasteurize Salmonella in black fungus (Auricularia auricula) powder. The effects of different conditions (initial a_w, electrodes gaps, particle sizes) on RF heating rate and uniformity were investigated. The results showed that RF heating rate was significantly (p < 0.05) improved with decreasing electrodes gap and increasing initial a_w, and the heating rate was the slowest when the particle size was 120-160 mesh. However, these factors had no significant (p > 0.05) influence on heating uniformity. RF pasteurization of Salmonella in black fungus powder was also studied. The results showed that, to inactivate Salmonella for 5 log reductions in the cold spot (the center of surface layer), the time needed and bacteria heat resistance at designated temperature (65, 75, 85 °C) decreased with increasing a_w, and the first order kinetics and Weibull model could be used to fit inactivation curves of Salmonella with well goodness. Quality analysis results showed that although RF pasteurization had no significant (p > 0.05) effect on Auricularia auricula polysaccharide (AAP) and total polyphenols, obvious changes were found on color. Results suggested that RF pasteurization can be considered as an effective pasteurization method for black fungus powder.

Sonication is a novel processing method that is perceived as a substitute for heat treatment to ensure the safety of juice while reducing the loss of nutrients during processing. The impacts of sonication and thermal processing on pineapple juice, including physicochemical properties, antioxidant activities, and microbial inactivation, were studied. Pineapple juice was sonicated at 100 W and 140 W (for 5, 10 and 15 min) and heat-treated at 70 °C, 80 °C and 90 °C (for 1 min). Results indicated minor alterations in physicochemical characteristics after sonication and thermal processing, while sonication treatment showed better retention of the color, clarity, and browning index of pineapple juice. Moreover, sonication significantly increased the bioactive compounds (total carotenoids, ascorbic acid, phenolics, and flavonoids) and boosted the antioxidant activity of pineapple juice compared to the heat-processed juice. Although sonication reduced the microbial load significantly with the increasing exposure time, it could not thoroughly inactivate microorganisms like thermal treatment. Therefore, optimal sonication processing conditions are required to be determined. This study will help the food processors utilize sonication treatment in pineapple juice processing plants to inactivate microorganisms thoroughly while also boosting the nutritional value.

In this study, the effects of homogenization sequence (before or after heat treatment) and homogenization temperature (40, 50 and 60 °C) for milk were investigated on physicochemical properties of stirred yoghurt. Stirred yoghurts were produced from homogenized and subsequently heat-treated milks, and heat-treated and subsequently homogenized milks and stored at 4 °C for 30 days. Number of grains, mean perimeter of grains, visual roughness, firmness, apparent viscosity, consistency coefficient in yoghurts produced from homogenized milk after heat treatment were higher, compared to those in yoghurts produced from milk homogenized before heat treatment, and these increased when homogenization temperature increased. To conclude, this study showed that some physicochemical properties of yoghurt were changed, by altering homogenization sequence and homogenization temperature for milk.

Combined use of hot water (HW) treatment and calcium lactate (CL) is a promising postharvest approach to preserve the food value and prolong the shelf life of fruits. The present experiment aims to determine the physiological loss in weight, firmness, respiration rate, ethylene and biochemical attributes of banana fruits treated with hot water (50 °C for 7 min) and aqueous CL dipping (1, 2, and 3% for 2 min). Treated fruits were stored under ambient conditions (22-25°C temperature and 60-65% of relative humidity) for up to 9 days. The study showed that combined use of HW and CL (3%) maintained higher hue angle, peel firmness (4.4 N), reduced decay loss (10.63%), respiration and ethylene evolution rate of stored fruits. Also, CL treatments (3%) with HW proved the best which reduced 6-fold sugar spot and 1.5-fold decay loss over untreated fruits. At the end of storage sensory parameters such as mouthfeel, peel colour and overall acceptability (score 6.9) were recorded higher in HW and CL 3% treated fruits. The findings indicated that pre-storage combined use of HW and CL has a great potential to preserve quality, delay ripening, and reduce sugar spots, and postharvest decay loss in banana fruit without any adverse effect on consumer appeal.