Effects of Technological Treatments and Storage on Probiotics Inoculated into Biscuits (Cookies) Made from Millet (<i>Pennisetum glaucum</i> L. R. Br.) and Tiger Nuts (<i>Cyperus esculentus</i> L.)

Background: The introduction of probiotics into food processing could give food products additional nutritional and functional properties. The objective of this study was to analyze the effects of technological treatments and storage on the vitality and viability of probiotics inoculated into biscuits made from millet and tiger nuts. Methods: Four types of biscuits were produced, depending on the heat treatment (37˚C or 40˚C) and the kind of sourdough used: Lactic Bacteria (LB) and Lactic Bacteria + Yeast (LB + S). The effects of the manufacturing processes on the fermentation and lactofermentation capacities (vitality) of the inoculated probiotics were evaluated by measuring the rate of pH decline. The viability of the strains was characterized according to ISO 21527, 2008 standard. Results: Technological treatments differently impacted the properties of probiotics inoculated into biscuits. The highest fermentation capacities were recorded with LBS biscuits treated at 40˚C and 37˚C, followed by LB biscuits treated at 37˚C and 40˚C. LB and LBS biscuits treated at 37˚C presented the best vitality. For viability, lactic bacteria in co-culture with yeasts (LBS) in biscuits showed a higher survival rate (32.50%) than that of lactic bacteria in monoculture (1.83%). The best lactofermentation capacities and vitality of probiotics were observed on Day + 1. Conclusion: This study could contribute to the development of adapted diagrams to increase the tolerance of probiotics to various stresses associated with technological processing and storage environment.