A REVIEW OF TEXTURAL DEFECTS IN COOKED RECONSTITUTED LEGUMES? THE INFLUENCE OF STORAGE AND PROCESSING

Abstract

Legumes provide an important part of the world's protein requirements, as well as other nutrients, but they are underutilized as food. A major factor limiting expanded consumption is storage induced textural defects that prolong cooking time and demand correspondingly higher energy requirements for preparation. Estimates of losses due to hardening are difficult to obtain but show the economic importance of the problem. These defects, including the hard-to-cook phenomenon and hard shell, are initiated by structural and compositional factors but can be at least partially controlled by storage and processing conditions. The available literature on bean hardening is reviewed from which it may be concluded that adverse storage conditions (high temperatures and humidities) consistently produce these defects. A kinetic approach is taken to the hardening problem, including hydration and cooking, which should allow a better understanding of the processes involved. Methods that can be utilized to produce better cooking legumes are reviewed as are processing alternatives including disruption and dry fractionation, wet fractionation, extrusion, enzymes and animal feeding. The influence of hardening on the nutritive value of legumes, although not extensively studied, is examined and it is concluded that protein quality and the availability of essential amino acids can suffer. A course of action for future research is recommended.