Microbial safety of oily, low water activity food products: A review

Oily, low water activity (OL a_w) products including tahini (sesame seed paste), halva (tahini halva), peanut butter, and chocolate, have been recently linked to numerous foodborne illness outbreaks and recalls. This review discusses the ingredients used and processing of OL a_w products with a view to provide greater understanding of the routes of their contamination with foodborne pathogens and factors influencing pathogen persistence in these foods. Adequate heat treatment during processing may eliminate bacterial pathogens from OL a_w foods; however, post-processing contamination commonly occurs. Once these products are contaminated, their high fat and sugar content can enhance pathogen survival for long periods. The physiological basis and survival mechanisms used by pathogens in these products are comprehensively discussed here. Foodborne outbreaks and recalls linked to OL a_w foods are summarized and it was observed that serotypes of Salmonella enterica were the predominant pathogens causing illnesses. Further, intervention strategies available to control foodborne pathogens such as thermal inactivation, use of natural antimicrobials, irradiation and hydrostatic pressure are assessed for their usefulness to achieve pathogen control and enhance the safety of OL a_w foods. Sanitation, hygienic design of manufacturing facilities, good hygienic practices, and environmental monitoring of OL a_w food industries were also discussed.

Evaluation of the effect of acetylsalicylic acid on Clostridium botulinum growth and toxin production

The Republic of Georgia (ROG) has the highest incidence of botulism among all countries in the world, with most cases attributed to home-preserved vegetables. Based on epidemiologic data, the occurrence of botulism in ROG is lower in areas where aspirin (active ingredient, acetylsalicylic acid [ASA]) is added to home-canned vegetables. The objective of this study was to evaluate, with a broth medium, the antibotulinal activity of ASA to determine the possible role of ASA in preventing botulinum toxin production in home-canned vegetables. Trypticase-peptone-glucose-yeast (TPGY) broth (pH 7.0) with 0, 0.3, and 0.6 mg of ASA per ml was inoculated with a 10-strain mixture of proteolytic Clostridium botulinum type A and B spores at ca. 10(3) spores per ml. The inoculated broths were incubated at 31 degrees C under anaerobic conditions, and C. botulinum growth and botulinum toxin production were determined for up to 36 h. Results showed ASA in broth delayed (time to initial detectable toxin produced and amount of toxin produced), but did not prevent, both growth and toxin production by C. botulinum. These results would not provide a definitive explanation for differences in toxin production in canned vegetables prepared with and without aspirin.

Survival, growth, and thermal resistance of Listeria monocytogenes in products containing peanut and chocolate

Outbreaks of listeriosis associated with the consumption of ready-to-eat foods have raised interest in determining growth, survival, and inactivation characteristics of Listeria monocytogenes in a wide range of products. A study was undertaken to determine the thermal tolerance of L. monocytogenes in a peanut-based beverage (3.1% fat), whole-fat (3.5%) milk, wholefat (4.0%) and reduced-fat (1.0%) chocolate milk, a chocolate-peanut spread (39% fat), and peanut butter (53% fat). The D60 degrees C value (decimal reduction time at 60 degrees C) in peanut beverage (3.2 min) was not significantly different (P > 0.05) than the D60 degrees C value in whole-fat milk (3.3 min) or whole-fat chocolate milk (4.5 min) but significantly lower (P < or = 0.05) than the D60 degrees C value in reduced-fat chocolate milk (5.9 min). The pathogen was significantly more resistant to heat when enmeshed in chocolate-peanut spread (water activity [aw] of 0.46; D60 degrees C = 37.5 min) and peanut butter (aw of 0.32; D60 degrees C = 26.0 min) than in liquid products. At 10 degrees C, the pathogen grew most rapidly in whole-fat chocolate milk and slowest in peanut beverage. At 22 degrees C, populations increased significantly within 12 and 16 h in whole-fat milk and reduced-fat chocolate milk, respectively, and within 8 h in whole-fat chocolate milk and peanut beverage. Initial populations (3.37 to 4.42 log CFU/g) of L. monocytogenes in chocolate-peanut spread and peanut butter adjusted to an aw of 0.33 and 0.65 declined, but the pathogen was not eliminated during a 24-week period at 20 degrees C. Survival was enhanced at reduced aw. Results indicate that a pasteurization process similar to that used for full-fat milk would be adequate to ensure the destruction of L. monocytogenes in peanut beverage. The pathogen survives for at least 24 weeks in chocolate-peanut spread and peanut butter at an aw range that encompasses that found in these products.

Shelf Life and Safety Concerns of Bakery Products—A Review

Bakery products are an important part of a balanced diet and, today, a wide variety of such products can be found on supermarket shelves. This includes unsweetened goods (bread, rolls, buns, crumpets, muffins and bagels), sweet goods (pancakes, doughnuts, waffles and cookies) and filled goods (fruit and meat pies, sausage rolls, pastries, sandwiches, cream cakes, pizza and quiche). However, bakery products, like many processed foods, are subject to physical, chemical and microbiological spoilage. While physical and chemical spoilage limits the shelf life of low and intermediate moisture bakery products, microbiological spoilage by bacteria, yeast and molds is the concern in high moisture products i.e., products with a water activity (a(w)) > 0.85. Furthermore, several bakery products also have been implicated infoodborne illnesses involving Salmonella spp., Listeria monoctyogenes and Bacillus cereus, while Clostridium botulinum is a concern in high moisture bakery products packaged under modified atmospheres. This extensive review is divided into two parts. Part I focuses on the spoilage concerns of low, intermediate and high moisture bakery products while Part II focuses on the safety concerns of high moisture bakery products only. In both parts, traditional and novel methods of food preservation that can be used by the bakery industry to extend the shelf life and enhance the safety of products are discussed in detail.