New approaches to Food Safety: study on food preservation and quality markers

In the last decades, the food market globalization, the introduction of novel foods, and growing demand for minimally processed, fresh-cut and ready-to-eat products have made the food chain more complex, increasing the risk of microbiological contamination. To obtain healthy food and prevent human foodborne diseases, research in the field of food science has focused on innovative food preservation technologies and study of quality markers. Actually, reduction in temperature, pH, water activity and the application of heat are the major preservation techniques employed to prevent or delay spoilage and are increasingly associated with hurdle technologies. The aim of the studies presented in this dissertation is to describe and analyze innovative food technologies and procedures to extent the shelf-life, assuring food hygiene and minimizing the impact on the quality properties of food. The Chapter I was focused on the biopreservation that rationally exploits the antimicrobial potential of naturally occurring (micro-) organisms in food and/or their metabolites. As alternative preservation technology, the aim of the study was to develop active biobased packaging incorporated natamycin as antimicrobial agent. Two active films based on chitosan (1,5% w/v)and methylcellulose (3% w/v) enriched with natamycin were prepared by casting. The migration kinetics of the antimicrobial agent were studied in the food simulant 95% ethanol (v/v) at different temperatures. The diffusion (DP) and partition coefficients were calculated by using a mathematical model based on Fick's Second Law. Natamycin was determined in the food simulant by reversed-high performance liquid chromatography with diode-array detection (HPLC-DAD). For microbiological analysis, cheese samples were completely covered with the films, stored at 20°C for 7 days, and then analyzed for molds and yeasts. Results showed that the release of natamycin from chitosan based film was slower if compared with methylcellulose film at the same temperature (P<0.05). Accordingmold/yeast count significant differences (P<0.05) were observed between chitosan film containing natamycin (7.91 log CFU/g) and polyethylene film, used as blank. Both chitosan and methylcellulose films seem to show good physical properties. Moreover, the good compatibility of natamycin with chitosan, low diffusion coefficient, and antimicrobial properties indicated that the film has great potential to be used in antimicrobial packaging, such as in cheese wrappings to inhibit mold spoilage. The application of antimicrobial agents to packaging materials could be useful to prevent the growth of microorganisms on the product surface and to improve microbial food safety. Chapter II reviewed a research regarding the influence of the pre-slaughter stress on animal welfare and poultry meat quality. The study investigated the effects of electrical stunning parameters on the quality of poultry meat in Ross commercial broilers processed either without stunning (NS Lot), or by combining high (HV Lot), and mid-voltage (MV Lot), with two frequencies of 1000 and 800 Hz. As pre-slaughter stress markers and quality meat indicators, physicochemical (pH, peroxides) and histological parameters (glycogen reserve, muscle damages) were investigated. Results showed as the use of high frequencies stunning conditions increased lactate production, induced a gradual pH decline(P<0.05), reduced the muscle oxidative activity(P<0.05), improving meat quality. To assess animal welfare and quality poultry meat, pH monitoring and measurement of superoxide radical production, might be considered markers easier to use under practical conditions at poultry slaughterhouse. In Chapter III, new models and approaches applied to decontamination of the poultry meat issue were described. Treatments of decontamination of poultry carcasses might assure food safety and the reduction of human foodborne infections. The aim of the study was to evaluate the effects of an experimental ozone gaseous treatment during the storage of chilled poultry carcasses by determination of biogenic amines as quality index. Physicochemical (pH determination), sensorial (panel test, questionnaire, and a scoring system), and chemical analysis (biogenic amines) were carried out. Amines were extracted with perchloric acid, derivative with dansylchloride, and separated by HPLC with a fluorescence detector. Results showed a gradual increase of pH values in poultry meat of treated and simply chilled carcasses. Ozonized carcasses showed acceptable sensory quality until to 20th day and lower levels of putrescine (32.37 mg/kg) and cadaverine (132.30 mg/kg). On the contrary, simply chilled poultry carcasses showed unacceptable sensory quality and a significant increase of putrescine and cadaverine at 15th day. Higher levels of putrescine (53.63 mg/kg) and cadaverine (175.20 mg/kg) were reached at 20t day of storage. If authorized, an ozone treatment during the storage of chilled poultry meat can induce a reduction of microbial contamination. Putrescine and cadaverine levels appeared to be useful to control the effectiveness of the ozone treatment on meat quality, to highlight, as quality index, the loss of poultry meat freshness, before sensorial meat changes. The novel and ambitious goal for optimal food preservation is the multitarget preservation of foods, in which intelligently applied gentle hurdles will have a synergistic effect. The application of innovative preservation methods with the monitoring of food quality by the use of markers could contribute to reach the purpose.