An investigation of the bacteriocinogenic potential of lactic acid bacteria associated with wheat (Triticum durum) kernels and non-conventional flours

One hundred and thirty-seven lactic acid bacteria (LAB), previously isolated from wheat (Triticum durum) grains and non-conventional flour samples, were tested for the production of antibacterial substances. A total of 16 strains (5 Enterococcus faecium, 5 Enterococcus mundtii, 4 Pediococcus pentosaceus, 1 Lactobacillus coryniformis and 1 Lactococcus garvieae) were found to inhibit the growth of Listeria innocua. The antibacterial activities were preliminarily investigated for their general behaviour with proteolytic (proteinase K, protease B and trypsin), amylolytic (-amylase) and lipolytic (lipase) enzymes, after heat treatment, and exposure to different pHs and ethanol concentrations. Bacteriocin-like inhibitory substances (BLIS) were also characterized for their inhibition spectra against non-pathogenic and pathogenic food-associated and human pathogenic bacteria. LAB showing the best characteristics in terms of inhibition spectrum, inhibition activity and mode of action (bactericidal) belonged to the species Ent. mundtii. The high percentage (11.68%) of BLIS-producing strains detected confirmed previous observations that raw materials may harbour higher numbers of bacteriocinogenic LAB than fermented foods.



Salivary-Amylase: A Measure Associated with Satiety and Subsequent Food Intake in Humans

Food intake regulation in humans involves various central and peripheral mechanisms. In this study salivary amylase was examined for functioning as a measure of satiety and food intake. In a 1.25-h session, 32 fasted subjects were given a preload of starch-based custard (849 kJ) followed by ad libitum intake of this custard. Before and after preload intake and after ad libitum consumption, both satiety ratings and -amylase were analysed. Perceived satiety and -amylase were increased after preload and ad libitum consumption. Across subjects, the individual amount of ad libitum intake was negatively correlated to -amylase levels before this intake, whereas it was positively associated with -amylase activity after ad libitum consumption. In conclusion, salivary -amylase systematically increases upon food consumption and satiation, and serves therefore as a potential measure of satiety and subsequent food intake.

Lucien F. Harthoorna

TI Food and Nutrition (WCFS), P.O. Box 557, 6700 AN Wageningen, The Netherlands
Wageningen UR, Agrotechnology & Food Sciences Group, Centre for Innovative Consumer Studies, P.O. Box 17, 6700 AA Wageningen, The Netherlands