This study focused to investigate the technological significance and the spoiling impact of diverse yeast strains, isolated from 'Bella di Cerignola' Italian table olives. Sixty-four isolates (belonging mainly to the species Candida famata and C. guilliermondii) were studied to assess their growth at different temperatures (15, 25 and 37°C), pHs (4.0, 5.0 and 9.5) and NaCl concentrations (0-10.0%) in lab medium. Their pectolytic, xylanolytic, lipolytic and catalase activities were also evaluated. Most of the yeasts showed a moderate pectolytic activity and were able to grow at pH 9.5 after 120 h of incubation. Salt and temperature were the most important environmental variables affecting yeast growth, which could exert a strong selective pressure on yeast population. Candida guilliermondii appeared more resistant to high salt concentrations, whereas C. famata was able to grow at 15°C.

The effectiveness of Ag + -based antimicrobial film in inhibiting the growth of an Alicyclobacillus acidoterrestris strain was assessed. The proposed active film was obtained by depositing via plasma an Ag-containing polyethylenoxide-like coating on a polyethylene layer. Tests were conducted at 44°C, monitoring the viable cell concentration of the investigated microorganism into 2 different media: acidified malt extract broth and apple juice. Results indicate that the investigated active film successfully inhibited the growth of A. acidoterrestris in both media. Results also indicate that the effectiveness of the film depends on the type of medium tested.

The study of different strategies for prolonging the shelf life of fresh minced beef patties was addressed in this work. Fresh minced beef was supplemented with thymol (THY) at levels of 250, 500 and 750 mg per kg of ground beef. Treated samples were packed using a high barrier film and stored in refrigerated conditions (4C) under ordinary atmosphere packaging and modified atmosphere packaging (MAP) conditions for 16 days. The microbiological quality decay kinetic was determined by monitoring the following microorganisms: Enterobacteriaceae, Pseudomonas spp., lactic acid bacteria, Brochothrix thermosphacta, coliforms and total psychrotrophic viable count. Results show that THY, working alone, was effective on coliforms and Enterobacteriaceae, whereas it does not seem to inhibit to a great extent the growth of the other microbial populations. On the other hand, an increased amount of THY, under MAP conditions, had better effects on the product quality, with a consequent prolongation of the shelf life.PRACTICAL APPLICATIONSGreat interest is developing in food bio‐preservation, because of the ever‐increasing needs to protect consumers' health and to valorize the naturalness and safety of food products. However, very few works have been carried out on the applications of bio‐preservatives to extend the shelf life of fresh meat products. This study, therefore, was mainly initiated to evaluate the possibility of extending the shelf life of packed fresh meat patties by a combination of thymol (THY) to other extrinsic factors such as storage temperatures and modified atmosphere during packaging. Interesting results were obtained suggesting that THY can perform an efficient synergy with modified atmosphere conditions and could be advantageously utilized by the meat industry.

Enterobacter cloacae can be recovered in the spontaneous fermentations of Italian table olives. In this study, the effects of salt (20 to 100 g/L), temperature (10 to 37 degrees C), pH (4 to 5 and 8 to 10), p-coumaric and vanillic acids (0.5 to 2 g/L), and the acidification of the medium through lactic, citric, and ascorbic acids were investigated on 15 strains of E. cloacae, isolated from Italian table olives "Bella di Cerignola." Finally, a confirmatory experiment in synthetic brine was run. The strains were inhibited only by an NaCl amount of 70 to 80 g/L and by p-coumaric acid; on the other hand, they showed the ability to grow also at low temperatures (10 to 15 degrees C). The confirmatory experiment highlighted their ability to survive both at 15 degrees C and at pH 5. Enterobacter cloacae could be a real problem for the fermentation of table olives in southern Italy; some hurdles could be used (salt or brine acidification), but some environmental conditions (for example, the temperature) should be controlled carefully to maintain olive safety at acceptable levels.

No abstract

The effect of nisin, lysozyme and lysozyme combined with disodium ethylenediaminetetraacetate salt (EDTA) for inhibiting the growth of spoilage micro-organisms in buffalo meat was investigated. Prior to packaging, the samples were alternatively dipped in solutions containing different concentrations of nisin, lysozyme and combinations of a pre-fixed amount of lysozyme and different concentrations of EDTA. The packed meat samples were stored at 4°C, and the microbial changes were monitored for a period of 8 days. The best results, in terms of microbial shelf-life extension, were obtained by dipping the meat steaks in a solution containing a combination of 0.5% of lysozyme and 2% of EDTA. This treatment was able to reduce the growth of all the investigated bacteria and showed a bactericidal effect on Brochotrix thermosphacta during the entire period of storage.

No abstract