Evaluation of process variables on the quality of egusi (Citrullus vulgaris) soup ball using response surface methodology.
Date
2024-07
Authors
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Journal ISSN
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Publisher
Federal University of Technology, Owerri
Abstract
This project was carried out to evaluate the effect of process variables on the quality of Egusi (Citrillus vugaris) soup balls from blends of defatted melon and “usu” Pleurotus tuber) flour. Egusi seeds were processed into flour and defatted while „Usu‟ was processed into flour. The two flour samples were blended at different ratios of (90:10, 80:20, 70:30) egusi / usu. A three factor, three levels Response Surface Methodology (Box Behnken Design) was used to design the experiment. Seventeen (17) runs were designed for feed composition X1(90:10, 80:20, 70:30) %, Cooking timeX2 (60, 90, 120) min and ball sizes X3 (5, 10, 15) g. The runs were used to produce soup balls. Sensory attributes andproximate composition of the soup balls were determined. Shelf – life study on the soup balls for a period of four weeks were also carried out. Regression models describing the effect of variables on the product responses were obtained. Proximate composition showed that there were significant (P<0.05) differences among the samples in terms of moisture content, crude protein, crude fibre, ash, fat, and carbohydrate samples. Responses were mostly affected to a large extent by feed composition, cooking time and to a lesser extent ball size. The moisture content of the soup ball samples was low, ranging from (5.75 -8.05%) which indicated that the samples would have longer shelf- life. The regression analysis results revealed that there were significant (P<0.05) differences in the interactions between feed composition and ball size and between ball size and cooking time. The coefficient of determination R2 was 0.87, which signified that the model adequately represented the real relationship between the variables under consideration. All the R2 were higher than 0.75. The lack of fits was not significant. The protein contents of the samples were high, ranging from (33.02 - 37.5%),which could be attributed to the protein content of the egusi. Fat content ranged from (7.67 – 10.23%). The fat content revealed that there was residual oil in the egusi flour after defatting. Screw oil expeller machine was used to defat the egusi which must have left residual oil in the flour. The response surface plot, fig. 4.5, revealed that increase in the percentage of egusi in the samples, resulted to increase in fat content of the samples. Increase of usu in the feed increased the crude fiber (2.95 – 6.63%) and ash content (4.01– 5.64%). Sensory scores showed that there were significant (P< 0.5) differences among the samples with respect to all the attributes. The scores were above 7.5 in a nine point hedonic scale. The highest total viable count after one month storage was 2.8x104cfu/ml from MSB13.The highest fungal count was 2.0 x104 cfu/ml from MSB1. No coliform count was detected. Though the counts were within acceptable levels, the following microorganisms were isolated: Bacillus subtilis, Pseudomonas aeruginosa (disease–causing); Aspergillus niger, Aspergillus flavus which were spoilage organisms.
Description
Masters thesis on the "process variables on the quality of egusi (Citrullus vulgaris) soup ball"
Keywords
Melon, pleurotus tuber, meat substitute, response surface, process variables, food science and technology
Citation
Onyejiaka, I. P. (2024). Evaluation of process variables on the quality of egusi (Citrullus vulgaris) soup ball using response surface methodology (Unpublished Master's Thesis), Federal University of Technology, Owerri