Semester of Graduation

Spring 2019

Degree

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Department

School of Nutrition and Food Sciences

Document Type

Thesis

Abstract

Probiotic products can improve gastrointestinal health and probiotics in ale beer may be attractive to health-conscious consumers. However, the alcohol in beer may decrease probiotic viability. A powder produced from durian fruit (Durio zibethinus) rind, a by-product that is currently unutilized, contains large amounts of fiber which can be used to immobilize probiotics. The objective of this study was to produce ale beer with free Lactobacillus brevis (FLB) and immobilized cells (ILB) on durian rind powder (DRP) as a potential delivery system for probiotics. L. brevis was immobilized in DRP then the morphology of FLB and ILB was observed with scanning electron microscopy (SEM). Ale beer was produced using standard brewing and fermentation procedures. FLB and ILB were separately added to the beer. Beer was then bottled and stored for 24 days at 21 °C. The physico-chemical characteristics of beer and viability of FLB and ILB in beer and in simulated gastric and intestinal conditions were evaluated. Microbial diversity of beer was also determined with 16s tag-encoded pyrosequencing. Data from triplicate experiments were statistically analyzed (p≤0.05). SEM results indicated that FLB and ILB were randomly attached to DRP. This indicated that DRP could be used for probiotic immobilization. The specific gravity, total soluble solids, pH, and titratable acidity of beer with FLB and beer with ILB did not differ significantly between both beers at 24 days of storage. FLB and ILB remained viable with counts of 4.89 and 5.00 log CFU/mL of beer, respectively, at 24 days. FLB and ILB had counts of approximately 5 log CFU/mL of beer after 120 min of exposure to simulated gastric and intestinal fluids, suggesting that ale beer containing FLB and ILB could deliver about 5 log CFU/mL of beer into the large intestine. The predominant bacterial species present were L. brevis at 61.88% and 55.68% in beer with FLB and beer with ILB, respectively, followed by L. farciminis. S. cerevisiae represented at least 99.99% of the fungal microbiota. This study demonstrated that beer with FLB and ILB could be a potential delivery system for probiotics.

Committee Chair

Sathivel, Subramaniam

Available for download on Monday, March 16, 2026

Included in

Food Science Commons

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