Changes in oral processing parameters of three rice varieties

Insights into the digestive processes of normal and high-amylose rice using realistic boluses formed in the bio-inspired oral mastication simulator (iBOMS-III)

Mastication is essential for preparing food bolus for swallowing and digestion. This study employed the bio-inspired oral simulator (iBOMS-III) to investigate the effects of mastication on physical properties and starch hydrolysis of normal rice (NR) and high-amylose rice (HR), while validating its results through comparison with in vivo data from human subjects. The median particle size (d50) of NR (1.266, 0.931, 0.776 mm) and HR (1.32, 1.04, 0.928 mm) boluses from iBOMS-III at 12, 14, and 20 cycles closely matched human boluses at the swallowing threshold, particularly after 14 and 20 cycles. Starch hydrolysis in NR increased from 76.6 % to 91.3 %, while HR hydrolysis ranged from 63.4 % to 73.3 %. Boluses from iBOMS-III with 14 and 20 cycles showed starch digestibility consistent with in vivo data (84.2 % for NR, 71.3 % for HR). These findings demonstrate that iBOMS-III effectively replicated human mastication behaviors, producing boluses comparable to those observed in vivo.

Chewing characteristics of rice and reasons for differences between three rice types with different amylose contents

This study investigated the physicochemical structural changes in different types of rice (japonica rice [JR], indica rice [IR], and waxy rice [WR]) during oral digestion and explored the reasons for differences in oral digestion between the three different types. The results showed that, compared with JR (42.41 ± 3.06 mg/g) and WR (26.82 ± 0.67 mg/g), IR had the highest amylose content (49.95 ± 3.33 mg/g) and, related to this, hydrolysis rate. A correlation analysis showed that, the higher the amylose content, the harder the texture of rice, leading to longer chewing times and, as a result, a greater degree of hydrolysis. In addition, the higher the amylose content, the lower the exudate content and viscosity of rice, which affects chewing time and frequency, thereby affecting the degree of hydrolysis. Both X-ray computed tomography and scanning electron microscopy indicated that cooked IR had the loosest structure and the most pores, that were conducive to chewing and crushing and therefore contributed to the high hydrolysis rate. Analysis of the exudate structure showed that the amount of exudate affected rice pores. More exudates lead to pore coverage and a tight structure.

Effect of chewing ability on in vivo oral digestive characteristics and in vitro gastrointestinal starch hydrolysis of three different types of cooked rice

Chewing ability has a strong effect on food digestion. However, little is known about the relationship between the food mastication degree and the subsequent gastric emptying. This study was to explore the effects of individual chewing ability (strong and weak) on the in vivo oral processing characteristics and in vitro dynamic gastrointestinal starch hydrolysis of three types of rice (japonica rice, indica rice and waxy rice). Results showed that the swallowable bolus in the weak chewing group had larger holes and a looser microstructure with more small rice particles, while the strong chewing ones obtained a bolus with higher saliva content (up to 28%) and starch hydrolysis degree (up to 13.55%). Moreover, the gastric retention and starch hydrolysis of the strong chewing ability group were higher in the artificial gastric dynamic system (AGDS). The indica rice particles with the higher degree of fragmentation contacted enzymes easier and hydrolyzed quicker, thus emptying through the stomach faster (81.76%). However, the oral chewing properties of rice mainly influenced the starch digestion in the stomach and the initial stage of the small intestine (∼5 min). This study suggested that the chewing ability and rice variety can influence the bolus properties, which in turn affected the gastric emptying and the degree of starch hydrolysis during digestion.

Characterization of japonica rice aroma profiles during in vitro mastication by gas chromatography-ion mobility spectrometry (GC-IMS) and electronic nose technology

By simulating the aroma changes during in vitro mastication, we can better understand the aroma changes during rice eating, which is helpful in studying people’s sensory preferences. To investigate the rice aroma released during the in vitro mastication, the present study analyzed rice bolus’s odor fingerprints in vitro mastication using electronic nose and gas chromatography-ion mobility spectrometry (GC-IMS). The electronic nose analysis results showed significant differences in the flavor of japonica rice in vitro mastication. In addition, GC-IMS determined 30 volatile organic compounds (VOCs) during rice in vitro mastication. Among these compounds, the most important content was aldehydes, followed by ketones and alcohols. Although the concentration of various chemicals was relatively high in cooked rice, most compounds decreased after mastication. The concentration of propan-2-ol, ethanol, and methanol increased after mastication. Multivariate data analysis showed that isoamyl sovalerate, pentanal, hexanal, acetone, hexanal, and limonene were the main VOCs of japonica rice during in vitro mastication. GC-IMS and e-nose analyses are complementary and recommended for using the two techniques to achieve the VOCs’ rapid and comprehensive detection during in vitro mastication. Results from this study allowed us to understand rice flavor during oral processing.

Assessment of physicochemical, rheological, and thermal properties of Indian rice cultivars: Implications on the extrusion characteristics

The implications of physicochemical, rheological, and thermal properties of seven eminent Indian rice cultivars (PR 114, 121, 122, 123, 124, 126, and 127) on the extrusion behavior and physico-functionalities of the extrudates were investigated. The amylose and amylopectin content of the cultivars ranged between 12.72 to 28.86% and 71.14 to 87.28% in addition with protein and crude fat content that varied from 7.05 to 9.15% and 0.49 to 1.17%, respectively. The onset (r = 0.98), peak (r = 0.95), and conclusion (r = 0.98) temperatures of the cultivars were in positive correlation with amylose. Likewise, pasting temperature (r = 0.979), final viscosity (r = 0.91), set back viscosity (r = 0.89), and stability ratio (r = 0.90) of the cultivars demonstrated a significant positive correlation with the amylose content. However, peak (r = - 0.879) and hold viscosity (r = - 0.89) were negatively correlated. The cultivars were extruded at feed moisture of 15%, screw speed of 500 rpm and barrel temperature of 150°C. The extrudates characteristics viz., expansion ratio-1.82 (PR 123); bulk density-184 g/cc (PR 123); specific mechanical energy-262.35 Wh/kg; water absorption index (WAI)-6.26 (PR 122); water solubility index-48.52% (PR 123); hardness-148.63 N (PR 122); and hydration power-284% (PR 122) were viably hyphenated with the physicochemical and rheological behavior of cultivars. The physico-functional characterization of the extrudates in terms of their starch and protein structural indexes, α-amylase susceptibility; water soluble carbohydrates and proteins revealed the possibility of exploring these cultivars as a functionally viable and diverse ingredient for the production of ready-to-eat extrudates.

Understanding the oral processing of solid foods: Insights from food structure

Understanding the relationship between the structure of solid foods and their oral processing is paramount for enhancing features such as texture and taste and for improving health-related factors such as management of body weight or dysphagia. This paper discusses the main aspects of the oral processing of solid foods across different categories: (1) oral physiology related to chewing, (2) in-mouth food transformation, (3) texture perception, and (4) taste perception, and emphasis is placed on unveiling the underlying mechanisms of how food structure influences the oral processing of solid foods; this is exemplified by comparing the chewing behaviors for a number of representative solid foods. It highlights that modification of the texture/taste of food based on food structure design opens up the possibility for the development of food products that can be applied in the management of health.