Effect of storage conditions on pectic polysaccharides in common beans (Phaseolus vulgaris) in relation to the hard-to-cook defect

Abstract

The importance of common beans (Phaseolus vulgaris) in addressing food insecurity cannot be underestimated. However, their utilization is hampered by development of the hard-to-cook (HTC) defect, i.e., the inability of cotyledons to soften sufficiently within a reasonable time during cooking, the presence of flatulence causing oligosaccharides, the antinutrients and the low digestibility of macronutrients. The objective of this study was to determine the effect of storage conditions (time, temperature and relative humidity) on pectic polysaccharides of selected common bean varieties during the evolution of the hard cook problem. First, alcohol insoluble residue (AIR) was extracted from the bean flour. The AIR was fractionated into water, chelator and Na 2 CO 3 -soluble pectin fractions and a hemicellulose fraction. The galacturonic acid content, neutral sugars, degree of methylesterfication (DM), degree of acetylation (DAc) and molar mass distribution for pectin fractions were determined. In addition, filterable residual protein in various fractions was estimated. Results on the acidic and neutral sugars revealed that common beans contained highly branched, arabinose-rich pectic polysaccharides. Storage of common beans for more than 4 months at high relative humidity (83%) and high temperature (45°C) resulting in HTC development showed a decrease in pectin extractability in water paralleled by an increase in the alkaline-soluble fraction. Other pectin characteristics such as DM and DAc showed minor variations upon storage of beans. The hydrolysis of both starch and proteins before AIR extraction decreased with increasing storage time, temperature and relative humidity. The increase in residual starch and protein might be linked to the protein-starch hypothesis where predominance of protein denaturation leads to restricted starch gelatinization. The results reveal that the contribution of pectic polysaccharides to development of HTC defect during the storage of Canadian wonder and Red haricot common beans at elevated temperature and relative humidity is due to reduced pectin solubility. However, the influence of starch and proteins seems evident.

Effects of refrigeration on biochemical, digestibility, and technological parameters of carioca beans during storage

“…As already discussed, several factors lead to an increase in cooking time and hardness of bean grains during storage. All these factors, associated with the interactions between the pectin fractions and starch, restrict the action of amylolytic enzymes capable of hydrolyzing the starch (Njoroge et al, ). Thus, the amount of energy provided by these grains is limited, which, hence, influences several people for whom carioca beans are considered as the staple food in their diet.…”

“…Lysine, an essential amino acid, is present in high concentration in carioca bean grains, but is limited in other basic grains such as rice and maize. Thus, the famous “beans and rice” meal, besides being tasty and appetizing, also provides the body with essential amino acids, considering that the rice is rich in methionine (Njoroge et al, ). In addition, several bioactive compounds, such as proanthocyanidins and ferulic, caffeic, synaptic, and gallic acids (Hayat, Ahmad, Masud, Ahmed, & Bashir, ), present primarily in the integument of bean grains, have been highlighted owing to their antioxidant, anti‐inflammatory, and anticarcinogenic properties (Campos‐veja, Loarca‐Piña, & Oomah, ; García‐Lafuente et al, ; Pintura & Arntfield, ).…”

“…However, inadequate control of factors affecting grain quality at this postharvest stage impairs the nutritional quality and technological and sensory properties of the grains, thus, reducing the commercial value (Ferreira et al, , ; Siqueira et al, ; Tulyathan & Leeharatanaluk, ; Ziegler, Ferreira, Hoffmann, Chaves, et al, ). Among the factors that affect grain quality during the storage period are moisture and grain temperature, temperature and relative humidity of the air in the storage environment, quality of the grains shortly after harvesting, and presence of insects (Nasar‐Abbas et al, ; Njoroge et al, ; Pohndorf, Meneghetti, Paiva, Oliveira, & Elias, ; Rani, Chelladurai, Jayas, White, & Kavitha‐Abirami, ; Strelec, Šarkanj, Mrša, & Ugarcic‐Hardi, ). Controlling these factors provides the lowest rates of metabolic activity in the grains during storage, and lower is the respiratory rate, lower is the consumption of energy reserves, representing their better conservation (Chidananda et al, ).…”

Pré-tratamento com radiação UV-C: influencias sobre as propriedades tecnológicas e metabólitos em feijão armazenado

“…O menor valor de taninos foi observado nos grãos não irradiados armazenados com 16% de umidade, onde também foi observado o maior tempo de cocção (Tabela 1). A redução dos taninos está associada ao aumento no tempo de cocção, pois a redução no conteúdo de taninos ocorre devido à polimerização ou complexação destes compostos principalmente com proteínas, reduzindo sua extração (STANLEY, 1992), dificultando a hidratação e consequentemente elevando o tempo de cocção (NJOROGE et al, 2015). Segundo Plhak et al (1987) flavonoides como antocianinas e proantocianidinas não estão envolvidos no processo de endurecimento, embora possam ser reduzidos durante o armazenamento.…”

Cowpea storage under nitrogen‐modified atmosphere at different temperatures: Impact on grain structure, cooking quality, in vitro starch digestibility, and phenolic extractability

“…HTC is a widely discussed phenomenon that occurs in beans stored under the inappropriate temperature, moisture content, and relative humidity conditions. Various complementary studies have been performed in order to explain this phenomenon, reporting HTC occurrence to be mainly associated with: (1) insolubilization of cell wall polymers (Shiga, Lajolo, & Filisetti, ); (2) lignification of the cotyledon cell wall constituents (Nasar‐Abbas et al, ); (3) reduction of pectin solubility as a result of mineral‐pectin interactions (Kruger, Minnis‐ndimba, Mtshali, & Minnaar, ); (4) covalent cross‐linking of pectin as well as increased interactions between starch and proteins, which hinders starch gelatinization (Njoroge et al, ); and (5) increased extent of interactions between the divalent ions and pectic polysaccharides (Yi et al, ).…”