Phytase–phytate–pectin hypothesis and quality of legumes cooked in calcium solutions

Abstract

Hard-to-cook and easy-to-cook bean and lentil seeds were boiled in water containing calcium ions at concentrations of 0, 40, 80, 120 and 160 mg L −1 and their texture and concentration of phytate and various peptic compounds were measured. In order to minimise matrix effects, hard-to-cook seeds were prepared from easy-to-cook seeds by soaking them at 50• C. It was found that, as calcium ion concentration increased, phytate concentration decreased and seed hardness increased. Also, during soaking and cooking, phytate and peptic compounds were leached into the water. Losses were larger for hard-to-cook seeds than for easy-to-cook seeds. These results are consistent with the proposed theory that the formation of hard-to-cook legume seeds involves an interaction among divalent cations, phytate and peptic compounds, which is based on the phytase-phytate-pectin hypothesis.  2007 Society of Chemical IndustryKeywords: phytase-phytate-pectin hypothesis; hard-to-cook; legumes INTRODUCTIONGrain legumes, especially common bean (Phaseolus vulgaris L.) and lentil (Lens culinaris Medicus), are a staple food for people in many parts of the world. A shortcoming of these legumes is the hard shell and associated hard-to-cook phenomenon that develop after storage under conditions of high temperature and relative humidity. This hardness and the concomitant need for long cooking times lead to reduced palatability, increased fuel consumption and reduced protein digestibility.1,2 Owing to the importance of legumes in the human diet, the hardto-cook phenomenon has been extensively studied.

Novel in situ evaluation of the role minerals play in the development of the hard-to-cook (HTC) defect of cowpeas and its effect on the in vitro mineral bioaccessibility

“…The phytate reduction in the current study was similar to that observed in HTC common beans (28%) and lentils (31%), which were stored for similar periods (Galiotou-panayotou et al, 2008). The phytate reduction was probably due to the intrinsic phytase activity of the cowpea, which has been found to be around 140 U/kg (Azeke et al, 2011).…”

“…Storage at temperatures and RH higher than prescribed above, is associated with the development of the HTC defect in cowpeas (Hentges et al, 1991). 2 Multiple possible mechanisms have been proposed for the development of the HTC defect (as described by Galiotou-Panayotou et al, 2008;Garcia et al, 1998).…”

“…Still, the most widely accepted proposed mechanism has been the ‗ph ytase-phytate-pectin' hypothesis (Galiotou-Panayotou et al, 2008;Phillips et al, 2003). This hypothesis states that during storage, high temperatures and high RH conditions are favourable conditions for the activity of intrinsic phytase, the enzyme which dephosphorylates phytate (inositol hexa-phosphate).…”

Sensory changes related to breeding for plant architecture and resistance to viruses and anthracnose in bean market class Fabada (Phaseolus vulgaris L.)

“…1 Pedigree selection 2 Backcross method in the seed, which decreases mealiness (Florez et al 2009;Galiotou-Panayotou et al 2008;Kigel 1999;Casanas et al 2006). We also observed significant differences between years for all the traits except seed coat roughness (Table 4).…”

Carbohydrate Profile of a Dry Bean (Phaseolus vulgaris L.) Panel Encompassing Broad Genetic Variability for Cooking Time

“…For example, storing beans for six months at 37°C and 75% rh caused cooking time to increase eightfold (Shiga et al 2004). Other factors include the insolubilization of pectin substances by phytase and pectin methylesterase enzymes, hydrolysis of storage proteins by proteases, oxidation of membrane lipids by lipoxygenases, and the lignification of cell wall polysaccharides from the oxidation of polyphenols by peroxidases (Moscoso et al 1984;Hinks and Stanley 1987;Reyes-Moreno and Paredes-Lopez 1993;Garcia and Lajolo 1994;Liu 1995;Garcia et al 1998;Galiotou-Panayotou et al 2008). Both enzymatic and nonenzymatic reactions are believed to be involved in the increased cooking times, resulting in physical and chemical changes that increase the stability of the middle lamella, inhibiting cell separation during cooking.…”