Antimicrobial potential of cauliflower, broccoli, and okara byproducts against foodborne bacteria.

The antimicrobial potential of cauliflower, broccoli, and okara byproducts was assessed against Gram-positive and Gram-negative bacteria. Salmonella enterica serovar Typhimurium, Escherichia coli O157:H7, Bacillus cereus, and Listeria monocytogenes serovar 4b growth behavior was assessed under exposure to 5% vegetable byproducts added to the reference medium, buffered peptone water (0.1% [wt/vol]), at 37°C. Although the byproducts were not effective against L. monocytogenes, they were bactericidal against Salmonella Typhimurium, E. coli O157:H7, and B. cereus. The most promising results were achieved with the cauliflower-Salmonella Typhimurium combination, because the bacterial population was reduced by 3.11 log10 cycles after 10 h of incubation at 37°C as a result of 5% cauliflower addition. Further studies were carried out for this combination, at different cauliflower concentrations (0, 0.5, 1, 5, 10, and 15%) and at temperatures in the range of 5-37°C. The greatest inactivation level (6.11 log10 cycles) was achieved at refrigeration temperature (5°C) using 15% cauliflower addition. Both temperature and cauliflower concentration significantly (p≤0.05) influenced the Salmonella Typhimurium inactivation level. The kinetic parameters were adjusted to mathematical models. The modified Gompertz mathematical model provided an accurate fit (root-mean-square error (RMSE) [0.00009-0.21] and adjusted-R(2) [0.81-0.99]) to experimental Salmonella Typhimurium survival curves describing inactivation kinetics of the pathogen to the antimicrobial effect of cauliflower byproduct.

Stevia rebaudiana Bertoni as a natural antioxidant/antimicrobial for high pressure processed fruit extract: processing parameter optimization.

Response surface methodology was used to evaluate the optimal high pressure processing treatment (300-500 MPa, 5-15 min) combined with Stevia rebaudiana (Stevia) addition (0-2.5% (w/v)) to guarantee food safety while maintaining maximum retention of nutritional properties. A fruit extract matrix was selected and Listeria monocytogenes inactivation was followed from the food safety point of view while polyphenoloxidase (PPO) and peroxidase (POD) activities, total phenolic content (TPC) and antioxidant capacity (TEAC and ORAC) were studied from the food quality point of view. A combination of treatments achieved higher levels of inactivation of L. monocytogenes and of the oxidative enzymes, succeeding in completely inactivating POD and also increasing the levels of TPC, TEAC and ORAC. A treatment of 453 MPa for 5 min with a 2.5% (w/v) of Stevia succeeded in inactivating over 5 log cycles of L. monocytogenes and maximizing inactivation of PPO and POD, with the greatest retention of bioactive components.

Pigment profile and colour of monovarietal virgin olive oils from Arbequina cultivar obtained during two consecutive crop seasons.

Monovarietal virgin olive oils are labelled with the olive varieties giving them their distinctive character. There are numerous studies focussed on the characterisation and quantification of the minor fractions of virgin olive oils that have generated databases on varietal olive oils. However, few studies have focussed on the components of the pigment fraction of virgin olive oils. The aim of this work was to quantify the components of the chlorophyll and carotenoid fractions of the monovarietal virgin olive oils from the Arbequina cultivar, growing in the Spanish area of Catalonia, during two consecutive crop seasons. Additionally the pigment changes occurring during 24 months of oil storage were evaluated. The results of this study showed minor qualitative differences between monovarietal virgin olive oils from two consecutive seasons. The quantitative differences could be attributed to the harvest period in each season rather than to the year's weather conditions. Storage of the monovarietal virgin olive oils probably caused an important loss of the chlorophyll fraction, mainly chlorophyll a, during the first 6 months of storage. On the other hand, the carotenoid fraction was very stable and the retention of provitamin A was close to 80%, even after 24 months of storage.