Effects of blanching and soaking on some physical characteristics of grass pea (<i>Lathyrus sativus</i>)

Abstract

Lathyrus sativus, containing a lathyritic principle, called ß-ODAP (ß-N-Oxalyl-L-α, ß-diaminopropionic acid), is widely grown and consumed in Ethiopia. It is a hardy crop grown under various agro-ecological situations. The major drawback in the use of the legume is the fact that the seeds, in common with other legumes, are not easily rehydrated, are difficult to cook, the seed coat is difficult to remove and long cooking time is required by traditional processing methods for tenderization. In this study, the effect of processing methods like blanching, soaking and cooking on water absorption, leached solids, swelling power, cooking time and sensory qualities of grass pea seeds were investigated. The soaking solutions used were mixed with salt solution, wood ash solution and double distilled de-ionized water. Blanching significantly (p < 0.05) increased total water absorbed, swelling power, leached solids and reduced cooking time compared to unbalanced seeds. Soaking blanched seeds in salt or wood ash solution was noted to be most effective in promoting seed softening during cooking, compared to double distilled water. Blanched grass pea seeds soaked for 12 hours in the three soaking solutions caused reduction of 60 %, 73 % and 68 %, respectively, in cooking time. In contrast, unblanched grass pea seeds soaked for 12 hours in the three soaking solutions caused reduction of 30 %, 46 % and 40 %, respectively, in cooking time. Water absorption, swelling power and leached solids values were negatively correlated (p < 0.05) with the cooking time. The study results indicated that blanching and hydration of grass pea seeds improved the sensory characteristics of cooked seeds, significantly reduced the cooking time and increased the weight and texture of the cooked seeds. Application of blanching preceded by soaking at village level as an integral part of traditional methods of processing grass pea seeds, thus offers the dual advantage of saving of valuable fuels by shortening cooking time, as well as rendering the seeds more acceptable to consumers. In the absence of salt, wood ash suspension treatment may be a satisfactory alternative in the production of quick-cooking grass pea seeds.

Effect of cooking methods on protein content and neurotoxin (β-ODAP) concentration in grass pea (Lathyrus sativus L.) grains

“…Ethiopian germplasm displayed the maximum variation for hydration and swelling capacity. These results agree with earlier findings of increase in grain weight of Ethiopian grass pea when soaked in water for 12 hours (Urga et al, 2006). Small-seeded grass pea germplasm of South Asia showed lower hydration and swelling capacity than the large seeded germplasm of Mediterranean countries.…”

“…Generally, grass pea grains are cooked whole or split as dhal based on the convenience and taste without considering the effect of cooking on antinutrient compounds like β-ODAP and nutritive value (Tarade et al, 2007). Soaking and cooking induce several changes in nutritional value of food legumes (Urga et al, 2006;Xu & Chang, 2008). Knowing these changes helps the consumer to prepare and cook food to maximize its nutritional value.…”

Efeito de diferentes concentrações salinas na redução do tempo de cocção de feijão (Phaseolus vulgaris L.)

“…Tal ruptura pode facilitar a cocção, no sentido de favorecer uma rápida entrada de água nos grãos hidratados em solução salina e posteriormente aquecidos em água fervente. Segundo Urga et al (2006), o tempo de cozimento em legumes é afetado pela permeabilidade do tegumento e dos cotilédones das sementes em água fervente. Durante a cocção dos grãos de feijão, a protopectina nativa existente na lamela média forma uma pectina solúvel que despolimeriza rapidamente durante o aquecimento e facilita a entrada rápida de água e o seu movimento para as células do cotilédone (Stanley e Aguilera, 1985).…”

“…De acordo com Costa et al (2001), o tempo de cozimento é fator fundamental para a aceitação de um cultivar de feijão pelos consumidores, pois a disponibilidade para o preparo das refeições é, muitas vezes, restrita. Ainda, o tempo prolongado de cozimento do legume não estimula o consumidor, devido à conveniência, o custo e ao valor nutritivo (Urga et al, 2006). Existe uma correlação negativa entre a absorção de água pelos grãos e o tempo de cocção, ou seja, quanto maior for a absorção de água, menor será o tempo de cozimento do grão.…”

Evaluation of cooking time and organoleptic traits of improved Dolichos (Lablab purpureus (L.) sweet) genotypes

“…by presoaking and subsequent discarding of the liquid and/or by heat treatment at relatively elevated temperatures (Wanjekeche et al, 2003). Prolonged cooking has a negative impact on beans; reducing their nutritive value especially vitamins and certain amino acids therefore results to the underutilization of the bean (Urga and Fufa, 2009). Sensory factors are a major determinant of the consumers" subsequent purchasing behavior (Mkanda et al, 2007).…”