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Effect of the Hard‐to‐Cook Phenomenon on Some Physicochemical Properties of Bean Starch

1988; Wiley; Volume: 40; Issue: 6 Linguagem: Inglês

10.1002/star.19880400602

2192-4236

Octavio Paredes‐López, E. C. Maza‐Calviño, R. Montes‐Rivera,

Proteins in Food Systems

Abstract Two bean varieties of outstanding agronomic performance were seeded, harvested and a portion stored for 135 days under high temperature and humidity. These varieties were Negro Qro and Canario with black and light yellow seeds, respectively. Hard‐to‐cook (HTC) defect developed in aged seeds as assessed by the Mattson cooker and Instron texturemeter. Fresh and HTC beans were used in order to determine physicochemical changes in starch and to evaluate its contribution in textural defects. The damaged starch content, water absorption and swelling were higher for isolated starches from HTC seeds than for the controls. Starch damage was generated by enzymatic attack and/or by mechanical action during milling. Pasting properties examined with the Brabender viscograph showed that peak viscosity increased and stability and retrogradation capacities declined after storage. These results might be ascribed to the starch damage and also to changes undergone by the residual impurities of isolated starches. In agreement with the previous observations, scanning electron microscopy of starch isolated from HTC samples revealed the presence of some swollen granules and many others with fissures, while those from controls had smooth surfaces and with no evidence of damage. Differential scanning calorimetry (DSC) evaluations showed that gelatinization temperatures and transition enthalpies were not significantly influenced by storage; results in agreement with birefringence studies. It is suggested that the changes in the starch from defective seeds were not sufficient to modify the gelatinization performance.