Submitted to: Journal of Food Engineering
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/11/2009
Publication Date: 10/22/2009
Citation: Pan, Z., Atungulu, G.G., Wei, L., Haff, R.P. 2009. Development of Impact Acoustic Detection and Density Separation Methods for Production of High Quality Processed Beans. Journal of Food Engineering. 97(3):292-300. Interpretive Summary: This research investigated and developed novel methods to produce high quality dehydrated precooked beans. The beans were sorted based on their acoustic and density characteristics before cooking. It suggested that only the portion of beans with high integrity is used for producing dehydrated precooked beans.
Technical Abstract: High rate of structural defects of finished bean products discourage their acceptance by consumers and end-users. Processing dry beans into high-value dehydrated precooked product can increase their value and improve the profitability of farmers and food manufacturers. This research investigated the acoustic characteristics and physical properties of dry beans (Phaseolus vulgaris L.) using impact acoustic detection (IAD) and density separation (DS) for improving the quality of dehydrated precooked beans. The developed IAD system consisted of a highly directional microphone, high speed data acquisition board and data analysis software with a real time Fast Fourier Transform (FFT) of which the integral against frequency (0 to 20 kHz) was called signal level. The DS method was achieved by using solutions of calcium nitrite and water. The IAD method separated beans depending on their skin damage, a basis not attainable by currently available methods. At 80 mm bean dropping height and 20° angle of impact, the skin-damaged beans were 65%, 62%, 30% and 15% for signal level of 0.02, 0.04, 0.06 and 0.08, respectively. The total broken dehydrated precooked pinto beans in the fraction with LSL was four times higher than that with HSL. The percentages of burst and split beans in the fraction with LSL were significantly higher than in HSL. Higher solid losses and hydration ratio were associated with low density. Beans with low density had larger size and weight, and more skin damage than beans with high density. At separation ratio of 34.9% (high density) and 33.5% (low density) the skin damage percentages were 12.96±4.19% and 45.78±0.71%, respectively, for pinto beans. The IAD and DS techniques offered advance and valuable information for high quality processing of dehydrated precooked beans.