Phenotypic, genotypic, and resistome of mesophilic spore-forming bacteria isolated from pasteurized liquid whole egg.

The production of whole-liquid eggs is of significant economic and nutritional importance. This study aimed to assess the phenotypic and genotypic diversity of mesophilic aerobic spore-forming bacteria (n = 200) isolated from pasteurized whole liquid egg and liquid egg yolk. The majority of the isolates were identified as belonging to the genera Bacillus (86 %), followed by Brevibacillus (10 %) and Lysinibacillus (4 %). For the phenotypic characterization, isolates were subjected to various heat shocks, with the most significant reductions observed at 80 °C/30 min and 90 °C/10 min for isolates recovered from raw materials. On the other hand, the decrease was similar for isolates recovered from raw material and final product at 100 °C/5 min and 110 °C/5 min. Genotypic genes related to heat resistance (cdnL, spoVAD, dacB, clpC, dnaK, and yitF/Tn1546) were examined for genotypic characterization. The dnaK gene showed a positive correlation with the highest thermal condition tested (110 °C/5 min), while 100 °C/5 min had the highest number of positively correlated genes (clpC, cdnL, yitF/Tn1546, and spoVAD). Whole Genome Sequencing of four strains revealed genes related to sporulation, structure formation, initiation and regulation, stress response, and DNA repair in vegetative cells. The findings of this study indicate that these mesophilic aerobic spore-forming bacteria may adopt several strategies to persist through the process and reach the final product. As the inactivation of these microorganisms during egg processing is challenging, preventing raw materials contamination and their establishment in processing premises must be reinforced.

Guarana seed extracts as a useful strategy to extend the shelf life of pork patties: UHPLC-ESI/QTOF phenolic profile and impact on microbial inactivation, lipid and protein oxidation and antioxidant capacity.

The antioxidant and antimicrobial effects of guarana seed extracts (GSE) added to pork patties were evaluated for 18 days storage at 2 ±â€¯1 °C. Five treatments were prepared: i) without natural antioxidant [control (negative control)], ii) with BHT at 200 mg/kg (positive control), and iii) with three different concentrations: 250  mg/kg (guarana seed low dose-GSL), 500  mg/kg (guarana seed medium dose-GSM) and 1000  mg/kg (guarana seed high dose-GSH) of guarana extracts, respectively. The pH, instrumental colour (CIE L*, a*, b*), total viable counts (TVC), Pseudomonas spp. counts and lactic acid bacteria (LAB) counts, 2-thiobarbituric acid reactive substances (TBARS) and carbonyl content were determined after 0, 7, 11, 15 and 18 days of storage period. The in vitro antioxidant activity together with the phenolic profile of GSE was also studied. Microbial analysis showed that GSE had no antimicrobial activity on pork patties. The untargeted UHPLC-ESI-QTOF approach confirmed the wide phenolic composition of GSE able to explain the antioxidant power (28.2 g/kg of phenolic equivalents). Low doses (GSL) of GSE were able to preserve the values of colour parameters, obtaining higher L*, a* and b* values during storage, which is reflected in the lowest colour differences during storage (ΔE*0-18 = 4.56). TBARS and carbonyls values in GSE added samples were lower than control and BHT ones. GSL and GSM provided better results than the synthetic antioxidant (0.08 and 0.07 vs 0.18 mg MDA/kg; 2.47 and 3.13 vs 3.23 nmol/mg, for GSL and GSM vs BHT, respectively). These findings show that GSE are very effective against colour deterioration, lipid and protein oxidation in pork patties and possessing the potential to be used as natural antioxidants.