Evaluation of the effects of soaking times and temperatures on the physicochemical properties of alkaline-cooked rice (Oryza sativa L.)

Date

6-2016

Degree

Bachelor of Science in Food Technology

Major Course

Major in Food Science

College

College of Agriculture and Food Science (CAFS)

Adviser/Committee Chair

Floirendo P. Flores

Abstract

The present investigation evaluated the effects of soaking times and temperatures on the physicochemical properties such as viscosity, amylose content, protein and starch during alkaline cooking applied to rice kernels. White rice (Super Angelika, Rc122) was cooked in saturated calcium hydroxide solution (.16% w/v 1:3 rice: solution) ratio at four different temperature (50, 60, 70, 80 °C) and four different cooking time (22, 44, 66, 88 min). The sample was then steeped in its cooking solution for 16-18 hours and washed until neutral to remove calcium present in the surface of the kernels. The wash water was analyzed for viscosity, apparent amylose, protein and starch content to determine the amount of the leached component after alkaline cooking. Thermal properties of alkaline-cooked rice was also determined. Alkaline cooking, temperature and time did not significantly (p𕟲.05) affected the viscosity of the alkaline cooked sample however, a slight decrease in viscosity was observed. On the other hand, protein and starch showed a similar leaching behavior that showed minimum leaching at 70°C. Alkaline cooking and temperature significantly (p𕟨.05) influenced the release of these components. Leaching out of these components are inhibited due to calcium ions interaction with starch and protein forming bonds that are difficult to disrupt that facilitates reorganization and increased rigidity of the network. Moreover, a substantial increase in amylose leaching was observed at 70°C and its effect is significant in alkaline cooking and temperature. Amylose content is considered as a significant parameter that would determine the effect time and temperature is amylose content because starch and protein showed similar response. The gelatinization temperature for 50-control, 50-sample, 70-control and 70-sample were 76.86±3.24°C, 72.55±4.50°C, 67.23±2.83°C, 68.25±1.64°C, respectively. Based from the results of the physicochemical properties of wash water, it was concluded that the intermediate soaking temperature (70°C) and intermediate time (44 min) would be useful for the application of alkaline cooking to rice.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2016 F61 /P87

Document Type

Thesis

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