Agricultural Research Management Information System

Home
Research Summary
Search
About Us
- ARMIS
- Brochure
Contact Us
Report
User Request
Data Input
Help
- Operation Manual
  - PDF
  - Video
- Program Area & Commodity
We have reached 37600 number of research entries at this moment.

- Logout

Research Detail

Home
Research
Detail

Moisture Sorption Characteristics of Selected Commercial Flours (wheat, Rice and Corn) of Bangladesh

M.W. Ahmed*
Department Agricultural Engineering, Sher-e -Bangla Agricultural University, Dhaka, Bangladesh

M.N. Islam
Department of Food Technology and Rural Industries, Bangladesh Agricultural University, Mymensingh, Bangladesh

Abstract/ Executive Summary:

Moisture sorption isotherms of commercial wheat flour, rice flour and cornflour were determined within the water activity range of 0.11-0.93 at different temperatures (5°C, 30°C, and 55°C) using the static gravimetric method. The moisture sorption isotherm of all flours exhibited type II characteristics according to BET classification. It was found that cornflour had a higher sorption capacity than wheat and rice flour. Temperature influence on sorption behavior was found that, for wheat and corn flour, the sorption capacity decreased with the increase of temperature, while for the rice flour an opposite behavior was observed at a water activity value higher than 0.75. The Clausius–Clapeyron equation was used to calculate the net isosteric heat of sorptions. For all flours, the heat of sorption decreased with the increase of EMC.

Keywords: Sorption isotherms, Wheat flour, Rice flour, Corn flour, Water activity

Location:

Start Date:

End Date:

Program Area: Crop-Soil-Water Management

Commodity: Wheat, Rice, Maize

Objectives:

The main objective of this research was to determine the sorption isotherm of three different commercial flour of Bangladesh (wheat, rice and corn). The specific objectives include proximate composition analysis and to observe the temperature effect on sorption behavior.

Methodology:

Commercial wheat flour (Bosundhora atta), cornflour (Noor-Nobi) and milled rice flour (BRRI-28 variety) collected from local market of Bangladesh Agricultural University, were used in this study. The Initial moisture content of the samples was determined by triplicate, taking 10-gram flour and dried in hot air oven as per ASAE recommendation. Following this method, we dried samples at 105°C until a constant weight was obtained. The initial moisture content of rice, wheat and corn flour was found 13.80%, 13.83% and 12.86% respectively on the dry weight basis (d.b). The collected rice, wheat and corn flours were analyzed for protein, fat and ash content as per AOAC. All experiments repeated three times. The static gravimetric method was used to determine the sorption characteristics of the flours over a water activity range of 0.11 to 0.93 at temperature 5, 30, and 55°C. Though the method takes a long time, it was reported as one of the most precise methods of moisture sorption analysis. The triplicate of rice, wheat and corn flour sample each weighing about 10 gram were put into the ceramic crucible and placed inside the glass desiccator. The saturated salt solution of LiCl, value was maintained 0.11, 0.2, 0.33, 0.44, 0.52, 0.68, 0.75, 0.85 and 0.93 respectively. An open flat container having uniform holes was used to hold crucibles, which was arranged in a way, so that crucible will not be in contact with the saturated salt solution. The marked desiccators were placed in a Genlab (England) Incubator (Model M75CPD) for maintaining the constant temperature. The incubator temperature was monitored to keep it within ±1°C. Samples were weighed periodically until weight variation was less than 0.001 g. It was found that equilibrium was attained within a maximum of 4 weeks. After equilibrium was reached, the equilibrium moisture content (EMC) of the samples was determined in triplicate according to the ASAE method.

Source of Information: American Journal of Food Science and Technology, 2018, Vol. 6, No. 6, 274-279 Available online at http://pubs.sciepub.com/ajfst/6/6/7

Article Link (Online Journal): DOI:10.12691/ajfst-6 -6 -7

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

The proximate analysis of commercial wheat, rice and corn flour of Bangladesh was done. Moisture sorption isotherms were analyzed over a water activity range of 0.11 to 0.93 at three temperatures 30°C, 5°C and 55°C. In all cases, a sigmoidal shape, characteristic of type II isotherms according to BET classification, was found. Corn flour found as the most hygroscopic flour at the higher water activity. The sorption capacity of all commercial flours decreased with the increase of temperature where a crossover of isotherms happens at around 0.75 water activity in rice flour. Net isosteric heats of sorption were calculated which was found to decrease with an increase of EMC.

Knowledge Management: Journal