Antimicrobial activity of food-compatible plant extracts and chitosan against naturally occurring micro-organisms in tomato juice

BACKGROUND: Chitosan (AC) and five hydroalcoholic extracts from Lithospermum erythrorhizon (SE), Rheum palmatum (RE), Thymus vulgaris (AT), Lippia citriodora (PLX) and a mixture of Rosmarinus officinalis, Salvia lavandulifolia and Thymus mastichina (LA) were tested for antimicrobial activity against bacteria, yeasts and filamentous fungi using two broth dilution methods. The effects of adding single extracts on naturally occurring micro‐organisms and sensory qualities of raw tomato juice were also evaluated. RESULTS: SE extract exhibited the strongest activity, with minimum inhibitory concentrations (MICs) of 100–400 µg mL^?1 for Gram‐positive and 1600–3200 µg mL^?1 for Gram‐negative bacteria. Enterobacter aerogenes showed the greatest susceptibility to AC (MIC 1600 µg mL^?1). Lethal effects of extracts and AC were achieved at a minimum bactericidal concentration (MBC)/MIC ratio of 2 in 88% of assays. SE and RE extracts and AC also exhibited antifungal effect against yeasts, but they had no activity on filamentous fungi. Control and 100 mg L^?1 SE‐added tomato juices did not differ in acceptance, but this SE concentration was not effective in the control of microbial load throughout cold storage. CONCLUSION: Results confirm the antimicrobial potential of the plant extracts, but additional research is needed until the agents responsible for the activities have been determined in order to use them as natural constituents of multiple‐barrier food preservation systems. Copyright © 2012 Society of Chemical Industry     

Survey of temperature and consumption patterns of fresh-cut leafy green salads: risk factors for listeriosis

Increasing demand for fresh-cut or ready-to-eat fruits and vegetables, developed to meet the consumer need for quick and convenient products, has prompted extensive research into their microbiological quality, safety, processing, and packaging. The microbial ecology of Listeria monocytogenes is recognized as a major safety concern for fresh-cut produce. A survey was performed to collect information on consumption patterns of fresh-cut leafy green salads and the temperature of domestic refrigerators. Salad consumption was low-moderate: 24.3% of respondents never purchased fresh-cut leafy green salads; of those who reported buying these products, 7.41% did so more than twice a week, 17.28% once or twice a week, 29.63% once or twice a month, and 45.68% occasionally. Saving time and convenience were the advantages most widely reported by consumers. A total of 9.9% of respondents did not always respect the "use-by" date of fresh-cut salads, a negative practice that could contribute to the risk of listeriosis. Temperatures reported in domestic refrigerators were compatible with the growth of L. monocytogenes on ready-to-eat salads. Variations in average temperature followed a normal distribution, N(6.62, 2.56), while the variability of temperature variance was described by a gamma distribution, G(2.00, 1.00). As expected, when a time of day-temperature profile was plotted over a 24-h period, changes corresponding to the transition between day and night were observed. Knowledge of consumption patterns and consumer hygiene practices is essential, first in assessing the risk of listeriosis (risk assessment) and second in taking measures to manage that risk (risk management).     

Changes on indigenous microbiota,colour, bioactive compounds and antioxidant activity of pasteurised pomegranate juice

Juices prepared from arils of ‘Mollar’ pomegranates were analysed for naturally occurring microorganisms, CIE Lab colour parameters, total phenols, anthocyanins and punicalagins, ellagic acid content and antioxidant capacity before and after low-, mild- and high-temperature pasteurisations (LTPs, MTPs and HTPs): 65, 80 and 90 °C for 30 or 60 s. Mean aerobic plate count (APC), yeast and mold count (YMC), and lactic acid bacteria (LAB) for fresh juices were 5.7, 5.36 and 4.0 log CFU/mL, respectively. MTPs and HTPs were sufficiently effective to decrease APCs to nil or negligible levels. An increase in CIE a values and decrease in CIE b values were the characteristic colour changes in heat-treated juices. The effect of pasteurisations showed that total phenols, punicalagins and ellagic acid were not much affected by thermal processing. Total anthocyanin content and antioxidant capacity were substantially and significantly influenced by the heat treatment applied. A linear relationship was observed between Trolox equivalent antioxidant capacity (TEAC) values and total anthocyanins, suggesting that they contributed strongly to the antioxidant capacity of pomegranate juice.     

Growth of Bacillus cereus in natural and acidified carrot substrates over the temperature range 5–30°C

Minimally processed refrigerated foods have a relevant potential in the food market, although the potential risk posed by sporulated emerging psycrotrophs pathogens has to be evaluated. Bacillus cereus is one of these pathogenic micro-organisms. In this paper, the ability to grow of several strains of B. cereus in nutrient broth and in a carrot-based substrate (broth) was evaluated. All the strains tested grew at 12°C or higher temperatures both in nutrient broth and in carrot substrate. One of the strains was able to grow rapidly even at 5°C. Acidification of the carrot substrate proved to be efficient inhibiting B. cereus. For the two strains tested, growth was not observed at pH below 4·75 acidifiying with citric acid or with lemon juice. When the effect of pH was combined with refrigeration, acidification at pH 5·0 was sufficient to inhibit B. cereus at 12°C or lower temperatures. Therefore, the combination of these two factors could have a great potential to control B. cereus growth in minimally processed foods, such as carrot based products. Additionally, lemon juice can be considered as a more natural alternative to citric acid.     

Postoperative analgesia in herniated disk surgery. Comparative study of diclofenac , lysine acetylsalicylate, and ketorolac

INTRODUCTION: Nonsteroidal anti-inflammatory drugs (NSAIDs) are effective in treating musculoskeletal pain and are theoretically ideal for treating postoperative pain of the lumbar column. OBJECTIVES: To compare the analgesic efficacy and side effects of treatment with 3 NSAIDs (lysine acetylsalicylate, ketorolac and diclofenac) in the treatment of pain after surgery for lumbar disc hernia. PATIENTS AND METHODS: We enrolled 75 ASA I-II patients undergoing discectomy because of lumbar disc hernia; balanced general anesthesia was used in all cases. The patients were randomly distributed in 3 groups based on type of analgesia given in the immediate postoperative period. Group A received lysine acetylsalicylate (1800 mg), group B received ketorolac (30 mg) and group C received diclofenac (75 mg). The analgesics were diluted in 100 mg of saline solution and administered through a peripheral vein over 10 min. We evaluated the analgesia attained on a visual analog scale (VAS) and the physiological response to pain was assessed by monitoring changes in arterial pressure, heart rate and breathing frequency. If analgesia was insufficient 30 min after administration of the drug, 200 mg of lysine cloximate was given as a top-up. The side effects of each drug were also recorded. RESULTS: VAS evaluation showed significant reductions in pain 60 min after administration in groups A and B and after 120 min in group C. Nine patients in each group required lysine cloximate. There were no significant differences in physiological response among the 3 groups. No patient suffered major side effects. Mild side effects were reported most often in group B. CONCLUSIONS: The NSAIDs studied were inadequately for treating pain after surgery for lumbar disc hernia. Ketorolac was no better than the other analgesics studied but was associated with a higher number of mild side effects.