Document Type

Thesis - Open Access

Award Date

2020

Degree Name

Master of Science (MS)

Department

Dairy Science

First Advisor

Padmanaban Krishnan

Keywords

Beverage, Partial Hydrolysis, Satiety, β- glucan

Abstract

Oats and barley are unique cereals owing to their nutritional and health benefits. Soluble dietary fiber components, especially β-glucan found in both grains, have been associated with the reduction of cholesterol, normalization of blood sugar levels and suppression of hunger. These nutritional and therapeutic attributes are ideal for production of novel and more diversified food products from these cereals. β-glucan, however, imparts high viscosity in food systems particularly in high moisture foods, thus impairing their sensory characteristics. Reduced viscosity oat-barley beverages, using partial enzyme and acid hydrolysis, may fill a void in the market segment and yet serve as effective vehicles for dietary fiber and protein enrichment. Reduced-viscosity beverages were developed containing blends of selected cultivars of oats and naked barley that were subjected to enzymatic and acid hydrolysis. Oat cultivar GMI 423 and Natty were combined with commercial barley flour in various oat:barley proportions (100%, 90:10, 80:20, 70:30, & 60:40), and beverages were then formulated using a standard recipe. A factorial analysis involved 20 beverages (2 hydrolysis treatments x 2 cultivars x 5 flour blends). The effects of partial enzyme and partial acid hydrolysis on beverage viscosity were evaluated. Nutritional and dietary fiber content were determined on flour and on beverages made with those flours in order to determine the efficacy of oat and barley enrichment. All analyses were conducted in duplicate. Sensory evaluation was done on all beverages to determine acceptance and preference of various attributes by untrained panelist (n =16). The most acceptable blend of high β- glucan beverage (80G/20B), low β-glucan beverage (80N/20B), (chosen during the sensory acceptability tests), together with a commercially available hunger suppressing beverage and regular breakfast (controls) were tested to compare their effects on satiety and food intake. These pasteurized selected beverages together with an unpasteurized control beverage, were subjected to shelf-life studies. Initial viscosities of novel beverages ranged between 149.35 – 184.5cP. Partial enzyme hydrolysis significantly reduced viscosities to 44.9 -57.5cP. Partial acid hydrolysis reduced the beverage viscosities to 130.1 – 170.1cP. Viscosity of the beverages also increased as the proportion of barley in the blend increased. The β-glucan content of GMI beverages, which ranged between 7.3 – 8.1% was reduced to 2.9 – 4.3% after treatment with partial enzyme hydrolysis. The β-glucan content was however not statistically significantly different from the partial acid hydrolyzed beverages which had a β-glucan content range between 4.4 – 5.3%. The initial β-glucan content of Natty beverages which ranged between 4.2 – 5.8%, was decreased to 1.32 – 1.39%, after partial enzyme hydrolysis. No significant difference was observed between the β-glucan content of the partial enzyme hydrolyzed Natty beverage and the partial acid hydrolyzed which had a β- glucan content range between 1.9 – 2.0%. GMI beverages were shown to have a higher protein content (12.5 -15.5%) compared with the beverages formulated with Natty (12.3 – 13.5%). The partial-enzyme hydrolyzed GMI beverage had a total dietary fiber (TDF) content of 7.6g per 240ml serving. This value was not significantly different in comparison to the unhydrolyzed GMI beverage which had a TDF content of 12.6g per 240ml serving. Similarly, the hydrolyzed Natty beverage which had a TDF content of 4.6g per 240ml serving was not significantly different from the unhydrolyzed Natty beverage with a TDF content of 7.3g per 240ml serving. The partial-enzyme hydrolyzed GMI beverages can be classified as high dietary fiber beverages. Paired preference sensory tests showed that, participants significantly preferred the partial-enzyme hydrolyzed samples over partial-acid hydrolyzed samples. QDA showed that partial enzyme hydrolyzed GMI and Natty beverages containing 80% oat and 20% barley were the most accepted with an overall acceptability value of 4.38 ± 0.60 and 4.63 ± 0.48, respectively. Satiety tests showed that reduction in hunger, desire to eat and prospective intake, was significantly greater with consumption of the high β-glucan beverage. The high β-glucan beverage decreased hunger by 48.53%, reduced desire to eat by 45.31%, lowered prospective intake by 29.09% and increased fullness from 2.8cm to 6.4cm, on a 10cm VAS scale, after the 4- hour postprandial period. Additionally, energy intake at lunch was significantly lower following consumption of the high β-glucan beverage (493.7 ± 176.2 kcal), compared to the commercial beverage (749.4 ± 171.4 kcal), regular breakfast (692.1 ± 195.6 kcal) and low β-glucan beverage (640.1 ± 132.0 kcal). The 4-week refrigerated shelf life study showed that pasteurized beverages had Aerobic Plate count and Coliform/E. Coli count, significantly below the FDA detection limit of 20,000 and 10cfu/g, respectively. This study demonstrates that it is possible to formulate an acceptable, functional high β- glucan beverage that is shelf stable under refrigerated conditions using partial enzyme hydrolysis.

Format

application/pdf

Number of Pages

169

Publisher

South Dakota State University

Rights

In Copyright - Educational use permitted http;//rightsstatements.org/vocab/InC-EDU/1.0/

Available for download on Wednesday, August 17, 2022

Included in

Food Science Commons

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