Changes in oral processing parameters of three rice varieties

Abstract

Mastication and saliva addition affects the formation of a bolus, directly playing a key role in people's eating enjoyment. However, the specific changes of oral physiological parameters and bolus moisture content in the oral processing of rice have not been studied in detail. Thus, in the present study, salivary flow rate, salivary secretion, chewing frequency, and bolus moisture content during oral processing of three rice varieties (japonica rice, indica rice, and glutinous rice) were fully investigated. The differences among different rice and changes among different oral processing stages (25%, 50%, 75%, and 100%) were analyzed. Results showed that the swallowing time of glutinous rice was significantly lower than that of japonica and indica rice (p < .05). However, there was no significant difference in the chewing frequency of the three rice varieties throughout the oral processing stages (1.59–1.66 Hz, p > .05). During oral processing, the salivary flow rates for the three kinds of rice decreased significantly (p < .05), from 37.72 ± 4.32 mg/s (0%–25% stage) to 19.83 ± 5.50 mg/s (75%–100% stage). The dry basis moisture content of the bolus increased significantly (p < .05), from 1.53 ± 0.08 (0%) to 1.96 ± 0.02 (100%). In the 75%–100% stage, the amount of saliva secretion for japonica rice was highest, followed by indica rice and glutinous rice (p < .05). At the point of swallowing (100% stage), the dry basis moisture content of all three rice‐bolus' was consistent (1.94–1.99, p > .05).

Establishment of an oral processing model for three varieties of rice

“…The rice cooking and preparation of the bolus were performed according to methods in Liu et al. (2020).…”

In vitro mastication of cooked rice: How it influences the bolus characteristics

“…The rice cooking method and preparation of the bolus were according to Liu et al (2020). Briefly, the rice was mixed with water (wt/wt, 1:1.2), soaked for 30 min at room temperature, and then cooked for 30 min in a rice cooker (HD3060, 2L, Philips, Amsterdam, Netherlands).…”

“…Saliva addition: To study the influence of saliva addition on the physical characteristics of the cooked rice bolus during in vitro mastication, the blending time was set at 20 s according to the cooked rice in vivo mastication time (Liu et al, 2020). The saliva addition amount was 100 mg/g, 200 mg/g, 300 mg/g, 400 mg/g, and 500 mg/g.…”

“…Blending time: To study the influence of blending time on the physical characteristics of the cooked rice bolus during in vitro mastication, the blending times were 5 s, 10 s, 15 s, 20 s, 25 s, and 30 s, respectively. The saliva addition amount was set at 300 mg/g according to the cooked rice in vivo mastication time (Liu et al, 2020).…”

“…In our previous studies, the influence of mastication on cooked rice boluses was quantified by changes in physical characteristics, such as water content (Liu, Ren, Asimi, Peng, & Zhang, 2020), particle size, texture, and rheology. In vivo mastication results have shown that the factors influencing the swallowing of Japonica rice include mastication time, mastication number, cohesiveness, and water content (dry wt basis) (Asimi et al, 2021).…”