Using ultrasonic-assisted sodium bicarbonate treatment to improve the gel and rheological properties of reduced-salt pork myofibrillar protein.

To study the impact of ultrasonic duration (0, 30, and 60 min) and sodium bicarbonate concentration (0% and 0.2%) on the gel properties of reduced-salt pork myofibrillar protein, the changes in cooking yield, colour, water retention, texture properties, and dynamic rheology were investigated. The findings revealed that added sodium bicarbonate significantly increased (P < 0.05) cooking yield, hardness, springiness, and strength of myofibrillar protein while reducing centrifugal loss. Furthermore, the incorporation of sodium bicarbonate led to a significant decrease in L⁎, a⁎, b⁎, and white values of cooked myofibrillar protein; these effects were further amplified with increasing ultrasonic duration (P < 0.05). Additionally, storage modulus (G') significantly increased for myofibrillar protein treated with ultrasonic-assisted sodium bicarbonate treatment resulting in a more compact gel structure post-cooking. In summary, the results demonstrated that ultrasonic-assisted sodium bicarbonate treatment could enhance the tightness of reduced-salt myofibrillar protein gel structure while improving the water retention and texture properties.

Comparative study on inhibitory effects of ferulic acid and p-coumaric acid on Salmonella Enteritidis biofilm formation.

Biofilm cells exhibit higher resistance than their planktonic counterparts to commonly used disinfectants in food industry. Phenolic acids are promising substitute offering less selective pressure than traditional antibiotics. This study aims to evaluate the inhibitory effects of ferulic acid (FA) and p-coumaric acid (p-CA) on Salmonella Enteritidis biofilm formation and explore the underlying inhibitory mechanisms. The minimal inhibitory concentration (MIC) of FA and p-CA were 1.0 and 0.5 mg/ml, respectively. The sub-inhibitory concentration (1/8 MIC) significantly decreased biofilm formation without growth inhibitory effects. The biomass and extracellular polymeric substances (EPS) of S. Enteritidis biofilm as well as the bacterial swimming and chemotaxis abilities were significantly decreased when exposed to sub-MIC concentrations of FA and p-CA. These two phenolic acids showed high affinity to proteins involved in flagella motility and repressed the S. Enteritidis biofilm formation-related gene expressions. Furthermore, these two phenolic acids maintained high antibiofilm efficiency in simulated food processing conditions. This study provided valuable information of multiple phenotypic and molecular responses of S. Enteritidis to these two phenolic acids.

Characterization and comparison of the bacterial community on environmental surfaces through a fresh-cut vegetables processing line in China.

Zoning is typically adopted by food manufacturers and classified into three different zones including Zone 1 (food contact surface), Zone 2 (proximity to food and food contact surfaces) and Zone 3 (remote surfaces from processing). In this study, environmental surfaces belonging to these three zones were sampled during food processing in a fresh-cut vegetables (FVs) processing facility located in Beijing, China. Bacterial loads in terms of aerobic plate count and coliform count were evaluated by culture-dependent techniques. The profile and diversity of bacterial community in these three zones were investigated by high-throughput sequencing. Zone 1 showed similar microbiota and predominated by Pseudomonas and Acinetobacter, while the predominant genera on Zone 2 or 3 were quite varied among different processing steps. The SourceTracker analysis showed that most of the bacteria (above 80%) on surfaces were from unknown sources, while sorting and disinfection & cleaning steps contributed equally to the bacterial community of cutting areas. Microbial association network analysis revealed strong positive interactions of Comamonas and Janthinobacterium with Myroides and Serratia, respectively, whereas Pseudomonas showed no significant correlation with other genera. The function of microbial communities was predicted based on BugBase 16S rRNA database, and the results indicated that the proportions of potential biofilm-forming bacteria were above 70% in all samples, and species of Pseudomonas, Comamonas, Chryseobacterium and Janthinobacterium were opportunistic pathogens or spoilage bacteria. This study evaluated the bacteria risks including bacterial load, composition, as well as potential bacterial interaction, function and microbial transfer on food processing surfaces, which will facilitate our better understanding on the cross-contaminations and preventions of harmful microorganism in FVs processing industry.

Occurrence of disinfectant-resistant bacteria in a fresh-cut vegetables processing facility and their role in protecting Salmonella enteritidis.

Chemical disinfectants are widely used to control foodborne pathogen contamination in fresh-cut vegetables (FVs) processing facilities. In this study, we investigated the disinfectant-resistant bacteria in a FVs processing facility and evaluate the effects of these bacteria on Salmonella enteritidis biofilm formation and disinfectant resistance. The disinfectant-resistance profiles were determined using 0.02% sodium hypochlorite (NaClO), 0.2% benzalkonium bromide (BAB) and 2% hydrogen peroxide (H2O2) solutions. The results showed the high occurrence of disinfectant resistant bacteria in the FVs processing environment, especially in the clean area. All isolates showed planktonic susceptibility to H2O2 and BAB, while the Gram-positive isolates were specifically resistant to NaClO. Isolates with biofilm-forming ability showed resistance to tested disinfectants. Disinfectant resistance of S. enteritidis was not significantly enhanced in most of the mixed-species biofilms, except for Bacillus paramycoides B5 which not only increased the biomass but also enhanced the survival ability of the Salmonella under NaClO treatment. Increased biomass and compact biofilm structures were observed in mixed-species biofilms by scanning electron microscopy (SEM). This study provides new insights into the disinfectant-resistant bacteria from food processing facilities and highlights their relevance for foodborne pathogen contamination.

Comparative effects of hawthorn (Crataegus pinnatifida Bunge) pectin and pectin hydrolyzates on the cholesterol homeostasis of hamsters fed high-cholesterol diets.

This study aims to compare the effects of feeding haw pectin (HP), haw pectin hydrolyzates (HPH), and haw pectin pentasaccharide (HPPS) on the cholesterol metabolism of hypercholesterolemic hamsters induced by high-cholesterol diets. The animals were fed a standard diet (SD), high-cholesterol diet (HCD), or HCD plus HP, HPH, or HPPS at a dose of 300mg/kg body weight for 4weeks. Results showed that HPPS was more effective than HP and HPH in decreasing the body weight gain (by 38.2%), liver weight (by 16.4%), and plasma and hepatic total cholesterol (TC; by 23.6% and 27.3%, respectively) of hamsters. In addition, the bile acid levels in the feces were significantly higher by 39.8% and 132.8% in the HPH and HPPS groups than in the HCD group. Such changes were not noted in the HP group. However, the HP group had higher cholesterol excretion capacities than the HPH and HPPS groups by inhibiting cholesterol absorption in the diet, with a 21.7% increase in TC excretion and a 31.1% decrease in TC absorption. Thus, HPPS could be a promising anti-atherogenic dietary ingredient for the development of functional food to improve cholesterol metabolism.