Application of coating on dog biscuits for extended survival of probiotic bacteria

Abstract

Functional biscuits for adult domestic dogs containing probiotic bacteria (Lactobacillus plan-tarum) and prebiotics (inulin) were developed and characterized. In order to assure a higherbacterial survival, the application of a protective coating was necessary. Two biscuit for-mulations were prepared, one with wheat flour and the other with soy and whole wheatflour. After baking them at 140◦C for 45 min, hard and crispy biscuits appropriate for adultdogs were obtained. Biscuits were treated either with calcium alginate or starch–glycerolcoating. The preferred coating formulation was the starch–glycerol because of a highersurvival rate of L. plantarum observed after passing through a simulated gastrointestinalsystem (HCl pH 1–2). In the case of wheat flour biscuits with coating, the bacteria survivalrate after passing through the in vitro system, showed higher survival rate, regardless thepresence of inulin while in soy and whole wheat flour biscuits, the presence of coatingdid not improve bacteria survival. The latter formulation showed a protective effect thusobtaining higher bacteria survival without coating. It is worth mentioning that after onemonth storage, biscuit formulations with coating maintained viable counts of L. Plantarumhigher than 108CFU/mL. The presence of inulin at 20 g/L did not show a significant effecton the survival rate of bacteria after one month storage period.