61A-4 |
Comparative effect of different enzymes on the long-term textural stability of shelf-stable bread |
A. H. BARRETT, Combat Feeding Program, PEFST, US Army Natick Soldier Center, Kansas Street, Natick, MA 01760-5018, G. Marando, and I. A. Taub, Combat Feeding Program, OSS. Bread and sandwich-type ration components used by the military must have long-term stability. While this bread is formulated for microbial stability, significant firming occurs during storage. Optimized formulation, including enzyme incorporation, can potentially minimize firming and increase acceptance. While other enzyme studies have employed only short timeframes, firming of shelf-stable bread has been determined to continue for several weeks. Thus, assessment of enzyme efficacy through longer storage periods is necessary. Our objectives were to compare the effectiveness of various amylolytic and proteolytic enzymes in reducing firming in shelf-stable bread stored for eight weeks. Standard “Meal, Ready-to-Eat” rolls were produced with manufacturer-recommended levels of: Grindamyl Max-life U3, U8, and U200 (amylases, Grinsted/Danisco), PR59 (a protease, Grinsted/Danisco), and “Eversoft Plus 995” (an alpha-amylase blend, American Ingredients). These rolls, and no-enzyme controls, were produced with and without glycerol. Samples, stored at 22C, were pulled at 2, 4, 6, and 8 weeks. Instrumental texture was assessed using compression to 50% strain. Stress-strain data were analyzed for deformability modulus and also fit to the function, y=(C1.x)/[(1+(C2.x)(C3-x)], in which C1 indicates relative firmness. Results were normalized for bulk density. Average stored firmness parameters were determined. In no-glycerol bread, greatest inhibition of firming occurred in PR59 and U3 samples (average stored modulus values were 45% and 48% of the stored control modulus, respectively; average stored C1 values were 29% and 40% of the stored control C1 value, respectively). U8, U200, and Eversoft had less pronounced effects. Enzymes had less effect in glycerol-containing bread. Enzymes can preserve bread texture during long-term storage, with the degree of protection depending on enzyme type. That both a protease and an amylase were effective supports the hypothesis that development of protein or starch-protein complexes, possibly altered by lower-molecular-weight carbohydrate reaction products, contributes to textural firming.
Session 61A, Carbohydrate
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