Technological and spoiling characteristics of the yeast microflora isolated from Bella Di Cerignola table olives

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.     

Characterization and Implications of Enterobacter cloacae Strains, Isolated from Italian Table Olives "Bella Di Cerignola"

ABSTRACT:  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 °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 °C). The confirmatory experiment highlighted their ability to survive both at 15 °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.     

Use of biodegradable films for fresh cut beef steaks packaging

A comparative study on the use of biodegradable films for fresh cut meat packaging is presented. Beef steaks were packaged using three different films: polyvinyl chloride (PVC), which is actually used to package this food product, a biodegradable polymeric film composed of starch and polyester and a biodegradable film composed of a mixture of three biodegradable polyesters. The packaged beef steaks were stored at 4 and 15 °C to simulate actual storage conditions and thermal abuse, respectively. Colour, total viable counts as well as spoilage microorganism counts were monitored over a period of 6 days. No substantial differences were observed among the beef steaks packaged using the three investigated films, suggesting that biodegradable films, such as those used in this investigation, could be advantageously used to replace PVC films in packaging of fresh processed meat, reducing in this way the environmental impact of polymeric films.     

Effect of Ag-containing Nano-composite Active Packaging System on Survival of Alicyclobacillus acidoterrestris

ABSTRACT: 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.     

Use of nisin, lysozyme and EDTA for inhibiting microbial growth in chilled buffalo meat

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.