"Crop elicitation": approccio innovativo per la valorizzazione delle proprietà funzionali in leguminose da granella

Crop elicitation: innovative approach for the valorization of grain legume functional properties. In Italy grain legume cultivation has encountered a drastic decrease due to several causes (productive, economic, social). In this regard, studies aimed at the setting up of agronomic techniques able to guarantee high and constant in planta yields of health-promoting compounds may concur at re-launching legume production. In this context, 22 accessions of grain legumes (17 Phaseolus vulgaris, 3 Phaseolus coccineus, 1 Vigna unguiculata and 1 Glycine max genotypes) were screened with the aim of identifying genotypes rich in health beneficial phytochemicals (α-amylase inhibitors, α -glucosidase inhibitors, polyphenols) and with low anti-nutritional compounds (lectins). A wide variability was observed among investigated accessions. Four genotypes (Verdone, Kidney Cina, Roviotto and DG) showed a α -amylase inhibitory activity significantly higher (approximately 30% more) than all other tested accessions. The α -amylase inhibitory activity was not correlated neither with the protein nor with the polyphenol contents. Conversely, the α -glucosidase inhibitory activity was positively correlated with grain color and polyphenol content: dark-colored seeds had a mean inhibitory activity of 83.64 ± 22.07%, whereas light-colored seeds had mean values of 21.11 ± 9.36%. As regards the anti-nutritional compounds, out of all common bean accessions, only DG showed no erythro-agglutination activity (lectins). Preliminary experiments, performed in controlled environment, permitted to highlight that different germination conditions markedly affect the synthesis and accumulation of functional compounds in legume seedlings. Those findings were confirmed with field trials performed in two different locations (Bologna and Pisa), on two bean genotypes (Verdone and Zolfino), during the 2004-2005 cropping season. Results showed that the application of abiotic stresses (no fertilization and /or no irrigation) lead to a significant increase of flavonoids in grains, but a decrease (up to 50%) in legume yields was also observed. Crop elicitation, even if valuable for boosting health-promoting compound synthesis in crops, must necessary cope with economically acceptable crop yields.

Advances in methods to detect, isolate and quantify foodborne pathogens

Foodborne diseases impact human health and economies worldwide in terms of health care and productivity loss. Prevention is necessary and methods to detect, isolate and quantify foodborne pathogens play a fundamental role, changing continuously to face microorganisms and food production evolution. Official methods are mainly based on microorganisms growth in different media and their isolation on selective agars followed by confirmation of presumptive colonies through biochemical and serological test. A complete identification requires form 7 to 10 days. Over the last decades, new molecular techniques based on antibodies and nucleic acids allow a more accurate typing and a faster detection and quantification. The present thesis aims to apply molecular techniques to improve official methods performances regarding two pathogens: Shiga-like Toxin-producing Escherichia coli (STEC) and Listeria monocytogenes. In 2011, a new strain of STEC belonging to the serogroup O104 provoked a large outbreak. Therefore, the development of a method to detect and isolate STEC O104 is demanded. The first objective of this work is the detection, isolation and identification of STEC O104 in sprouts artificially contaminated. Multiplex PCR assays and antibodies anti-O104 incorporated in reagents for immunomagnetic separation and latex agglutination were employed. Contamination levels of less than 1 CFU/g were detected. Multiplex PCR assays permitted a rapid screening of enriched food samples and identification of isolated colonies. Immunomagnetic separation and latex agglutination allowed a high sensitivity and rapid identification of O104 antigen, respectively. The development of a rapid method to detect and quantify Listeria monocytogenes, a high-risk pathogen, is the second objective. Detection of 1 CFU/ml and quantification of 10–1,000 CFU/ml in raw milk were achieved by a sample pretreatment step and quantitative PCR in about 3h. L. monocytogenes growth in raw milk was also evaluated.