Digestion of isolated legume cells in a stomach-duodenum model: three mechanisms limit starch and protein hydrolysis

Abstract

Retention of intact plant cells to the end of the small intestine leads to transport of entrapped macronutrients such as starch and protein for colonic microbial fermentation, and is a promising mechanism to increase the content of resistant starch in diets. However, the effect of gastro-intestinal bio-mechanical processing on the intactness of plant cells and the subsequent resistance to enzymatic digestion of intracellular starch and protein are not well understood. In this study, intact cells isolated from legume cotyledons are digested in a laboratory model which mimics the mechanical and biochemical conditions of the rat stomach and duodenum. The resulting digesta are characterised in terms of cell (wall) integrity as well as intracellular starch and protein hydrolysis. The cells remained essentially intact in the model with negligible (ca. 2-3%) starch or protein digestion; however when the cells were mechanically broken and digested in the model, the hydrolysis was increased to 45-50% suggesting that intact cellular structures could survive the mixing regimes in the model stomach and duodenum sufficiently to prevent digestive enzyme access. Apart from intact cell walls providing effective barrier properties, they also limit digestibility by restricting starch gelatinisation during cooking, and significant non-specific binding of α-amylase is observed to both intact and broken cell wall components, providing a third mechanism hindering starch hydrolysis. The study suggests that the preservation of intactness of plant cells, such as from legumes, could be a viable approach to achieve the targeted delivery of resistant starch to the colon.

Understanding the Relations Among the Storage, Soaking, and Cooking Behavior of Pulses: A Scientific Basis for Innovations in Sustainable Foods for the Future

“…Apart from the incorporation of flours and/or powders of pulses in food formulations, current research trends are on the nutraceutical functionalities of pulses (Chávez‐Mendoza & Sánchez, ; Díaz‐Sánchez, Guajardo‐Flores, Serna Guerrero, Gutierrez‐Uribe, & Jacobo‐Velázquez, ; Jamdar, Deshpande, & Marathe, ; Jing et al., ) as influenced by different processing methods (López‐Martínez, Leyva‐López, Gutiérrez‐Grijalva, & Heredia, ) or, more specifically, bioactivity of peptides and hydrolysates (Carbonaro, Maselli, & Nucara, ; Luna‐Vital et al., ) as well as hydrolyzability of the proteins and related physicochemical characteristics (Ghribi et al., ; Jamdar et al., ; Torres, Rutherfurd, Muñoz, Peters, & Montoya, ; Worku & Sahu, ). Other studies involve in vitro starch digestion (Bhattarai, Dhital, Wu, Chen, & Gidley, ; Dhital, Bhattarai, Gorham, & Gidley, ; Edwards et al., ; Ma, Wang, Wang, Jane, & Du, ; Pallares Pallares et al., ; Rovalino‐Córdova, Fogliano, & Capuano, ).…”

Surface structural features control in vitro digestion kinetics of bean starches

“…The unbound excess dye was removed by repetitive centrifugation (2200g) in excess water. Confocal microscopic images were acquired at 488 nm excitation wavelength using a confocal microscope (LSM 700, Carls Zeiss, Germany) (Bhattarai, Dhital, Wu, Chen, & Gidley, 2017).…”

Effects of the gastric juice injection pattern and contraction frequency on the digestibility of casein powder suspensions in an in vitro dynamic rat stomach made with a 3D printed model

“…The DIVRS-II has also been used to study the fate of starch and protein, and the effect of porcine gastric mucin on digesta rheology and gastric emptying rate as well as hydrolysis of macronutrients in control, pectin and mango diets with different dry matter contents (Wu et al, 2017a). Recently, Bhattarai, Dhital, Wu, Chen, & Gidley (2017) used the DIVRS-II to investigate the effect of legume cell walls on the hydrolysis rate and extent of starch and protein in isolated cooked legume cells occurred in the gastric and small intestinal phases. Although the DIVRS-II has been improved significantly in performance, it still has some shortcomings.…”