Phenolic compounds and extracts with bioactive properties can be obtained from many kinds of plant materials. These natural substances have gained attention in the food research as possible growth inhibitors of foodborne pathogenic and spoilage bacteria. Many phenolic-enriched plant extracts and individual phenolics have promising anti-quorum sensing potential as well and can suppress the biofilm formation and toxin production of food-related pathogens. Various studies have shown that plant phenolics can substitute or support the activity of synthetic food preservatives and disinfectants, which, by the way, can provoke serious concerns in consumers. In this review, we will provide a brief insight into the bioactive properties, i.e., the antimicrobial, anti-quorum sensing, anti-biofilm and anti-enterotoxin activities, of plant phenolic extracts and compounds, with special attention to pathogen microorganisms that have food relation. Carbohydrase aided applications to improve the antimicrobial properties of phenolic extracts are also discussed.

Mobilization of phenolic antioxidants from grape, apple and pitahaya residues via solid state fungal fermentation and carbohydrase treatment

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Salmonella spp. prevails as the main cause of raw meat foodborne illnesses. Implementation of food safety management systems such as Hazard Analysis and Critical Control Points in swine abattoirs can help to mitigate pathogen exposure. The objective of the present study was to evaluate the impact of the HACCP system in slaughterhouses in Colombia on reducing Salmonella spp. exposure due to the consumption of fresh pork meat. Two slaughtering plants with a different degree of HACCP implementation were selected and a quantitative microbiological mapping was built by collecting 820 samples of Salmonella spp. enumeration at different processing stages. The overall Salmonella spp. mean concentration was 1.15 ± 0.55 log MPN/g, with no significant differences among plants ( P > 0.05). Deficiencies during carcass disinfection and temperature during distribution of meat cuts from the slaughterhouse lacking of HACCP resulted in a significant increase of Salmonella spp. prevalence (20–40%) ( P < 0.05). Processing stages with the highest pathogen prevalence were transport (28–32%) and hanging (16–36%). The exposure assessment model estimated a higher degree of pathogen contamination at the time of consumption in meat cuts from the slaughterhouse without HACCP (3.36 versus 3.68 log MPN/g) and 10-fold increase in the probability a consumer would acquire a contaminated portion (0.011 versus 0.105). Implementation of the HACCP system in swine slaughterhouses represents tangible Salmonella spp. reduction control and public health protection measures.

Lipase enzymes of the oleaginous fungal group Mortierella are rarely studied. However, considering that most commercial lipases are derived from filamentous fungal sources, their investigation can contribute to the cost-effective development of new biotechnological processes. Here, an extracellular lipase with a molecular mass of 30 kDa was isolated from Mortierella echinosphaera CBS 575.75 and characterized. The purified lipase exhibited an optimal p-nitrophenyl palmitate (pNPP)-hydrolyzing activity at 25 °C and pH 6.6–7.0 and proved to be highly stable at temperatures up to 40 °C and under broad pH conditions. The enzyme was active under low temperatures, retaining 32.5% of its activity at 10 °C, and was significantly stable in polar and non-polar organic solvents. The Km, Vmax, and kcat for pNPP were 0.336 mM, 30.4 μM/min, and 45.7 1/min for pNPP and 0.333 mM, 36.9 μM/min, and 55.6 1/min for pNP-decanoate, respectively. The pNPP hydrolysis was inhibited by Hg2+, N-bromosuccinimide, and sodium dodecyl sulfate, while ethylenediaminetetraacetic acid and metal ions, such as Ca2+, Mg2+, Na+, and K+ enhanced the activity. The purified lipase had non-regioselective activity and wide substrate specificity, showing a clear preference for medium-chained p-nitrophenyl esters. Besides its good transesterification activity, the enzyme appeared as a suitable biocatalyst to operate selective esterification reactions to long-chained alkyl esters. Adsorption to Accurel MP1000 improved the storage stability of the enzyme at 5 °C. The immobilized lipase displayed tolerance to a non-aqueous environment and was reusable for up to five cycles without significant loss in its synthetic and hydrolytic activities. These findings confirm the applicability of both the free and the immobilized enzyme preparations in future research.