University of Avignon

About: University of Avignon is a education organization based out in Avignon, Provence-Alpes-Côte-d'Azur, France. It is known for research contribution in the topics: Population & Speaker recognition. The organization has 1526 authors who have published 3766 publications receiving 88928 citations.

Pulsed light treatment as new method to maintain physical and nutritional quality of fresh-cut mangoes

Abstract: This study investigated the impact of pulsed light treatment on physical and nutritional quality of fresh-cut “Kent” mangoes. Pulsed light treatments were carried out using an automatic flash lamp system (Mulieribus, Claranor) composed of eight lamps situated all around the sample with a total fluence of 8 J cm − 2 . Firmness, colour, phenol, carotenoid, ascorbic acid contents and enzyme activities (Phenylalanineammonialyase, PAL and Polyphenoloxydase, PPO) were analysed. Pulsed light treatment maintained the firmness, the colour and the carotenoid content of fresh-cut mangoes. The treatment increased PPO activities after 3 days and maintained PAL activity. For the nutritional aspect, pulsed light maintained phenol and total ascorbic acid contents such as the control. Our results suggest that the application of pulsed light could be used with fresh-cut mangoes to improve physical quality and maintain nutritional properties. Industrial Relevance Mango is one of the most important tropical fruit worldwide with an increasing demand for “ready to eat” products, because of convenience and fresh-like quality. However, fresh-cut mangoes suffer from browning and softening. Conventional thermal treatments decreased the browning but may contribute to the degradation of certain component. Nowadays, alternative nonthermal technologies are more and more studied such as Pulsed Light. In industry, Pulsed light is used to decontaminate surfaces, packaging or food (bread). No application is available on fruits and vegetables. This work estimated the feasibility of pulsed light treatment to improve the quality of fresh-cut mangoes. The results obtained are promising and could improve the use of pulsed light treatment to extend the shelf-life of fresh-cut products.

Control of Enterotoxin Gene Expression in Bacillus cereus F4430/73 Involves the Redox-Sensitive ResDE Signal Transduction System

Abstract: In contrast to Bacillus subtilis, the role of the two-component regulatory system ResDE has not yet been investigated in the facultative anaerobe Bacillus cereus. We examined the role of ResDE in the food-borne pathogen B. cereus F4430/73 by constructing resDE and resE mutants. Growth performances, glucose metabolism, and expression of hemolysin BL (Hbl) and nonhemolytic enterotoxin (Nhe) were analyzed in the three strains under distinct oxygenation and extracellular oxidoreduction potential (ORP) conditions. We show that growth and glucose metabolism were only moderately perturbed in both resDE and resE mutants under aerobiosis, microaerobiosis, and anaerobiosis generated under N2 atmosphere (initial ORP = +45 mV). The major effects of resDE and resE mutations were observed under low-ORP anaerobic conditions generated under hydrogen atmosphere (iORP = −148 mV). These conditions normally favor enterotoxin production in the wild type. The resE mutation was more deleterious to the cells than the resDE mutation, causing growth limitation and strong deregulation of key catabolic genes. More importantly, the resE mutation abolished the production of enterotoxins under all of the conditions examined. The resDE mutation only decreased enterotoxin expression under anaerobiosis, with a more pronounced effect under low-ORP conditions. Thus, the ResDE system was found to exert major control on both fermentative growth and enterotoxin expression, and it is concluded that the ResDE system of B. cereus should be considered an anaerobic redox regulator. The data presented also provide evidence that the ResDE-dependent regulation of enterotoxins might function at least partially independently of the pleiotropic virulence gene regulator PlcR.

In vivo metabolic fate of [14C]-acetamiprid in six biological compartments of the honeybee, Apis mellifera L

Abstract: The in vivo metabolism of acetamiprid was studied in the honeybee, Apis mellifera L. The distribution of acetamiprid and its metabolites was monitored over a 72-h period in six biological compartments: head, thorax, abdomen, haemolymph, midgut and rectum. Honeybees were treated orally with 100 microg [14C]-acetamiprid kg(-1) bee, a dose which is about 1500 times lower than the median lethal dose. After 72 h, only 40% of the total radioactivity was eliminated, suggesting that acetamiprid and its metabolites tended to persist in the honeybee. Acetamiprid was rapidly distributed in all compartments and metabolized. Just after administration, radioactivity was mainly localized in the abdomen and subsequently in the rectum. After 72 h, the maximum amount of radioactivity (about 20% of the ingested dose) was detected again in the abdomen, whereas the lowest level of total radioactivity was detected in the haemolymph. Radioactivity in the head did not exceed 7.6% of total ingested radioactivity. More than 50% of acetamiprid was metabolised in less than 30 min, indicating a very short half-life for the compound. During the first hours, acetamiprid was mainly detected in nicotinic acetylcholine receptor-rich tissues: abdomen, thorax and head. Of the seven metabolites detected, the major ones were 6-choronicotinic acid and an unknown metabolite called U1, which was present mainly in the rectum, the thorax and the head. Our results indicate that the low toxicity of acetamiprid may reflect its rapid metabolism.