Influence of Blanching on Some Nutrient and Anti-nutrient Compositions of Bitter Yam (Dioscorea dumetorum) | Chapter 04 | Advances in Applied Science and Technology Vol. 7

Bitter yam (Dioscorea dumetorum) is essentially underutilized probably due to its characteristic bitter taste. The bitter taste may be related to its nutrient and anti-nutrient mix which could be improved by simple processing methods. The study evaluated the influence of blanching on some nutritient and anti-nutrient compositions of bitter yam (Dioscorea dumetorum) flour obtained after blanching (at 100°C) for varied time. The study was conducted at the Department of Food Technology, School of Industrial and Applied Sciences, Federal Polytechnic Nekede, Nigeria. The nutrients and anti-nutrients in the blanched and unblanched samples were determined by standard methods. The content in the sample blanched for 18 minutes increased respectively by 1.88% and 1.13% for moisture and carbohydrate, but decreased, by 60.00%, 19.61%, 5.80% and 13.65% for fat, crude fibre, ash and protein relative to control (0 minute). Blanching caused a decrease by 67.43% and 62.26% for alkaloid and tannin in the sample blanched for 18 minutes relative to control. The results were time dependent and significant (p<0.05). Thus, although the significant reduction in tannin and alkaloid may improve taste, the process reduced many important nutrients and may diminish the keeping quality of the resultant flour. Thus, we recommend the processing method when bitter yam flour is required for immediate use and as a low fat-energy source. Since many nutrients and anti-nutrients (medicinal components) could leach into the blanch water, further study on the utilization of the waste water and other processing methods is warranted.

Author(s) Details

Anthony Cemaluk C. Egbuonu
Department of Biochemistry, College of Natural Sciences, Michael Okpara University of Agriculture, Umudike, Nigeria.

Daniel C. Nzewi
Department of Food Technology, School of Industrial and Applied Sciences, Federal Polytechnic, Nekede, Nigeria.

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Effects of Processing on Proximate Composition of Hibiscus rosa-sinensis Leaf | Chapter 14 | Recent Advances in Biological Research Vol. 3

Leaves of Hibiscus rosa-sinensis are processed using different methods depending on the intended application. Using three different processing methods, we investigated the effects of processing on the proximate constitution of the leaf. Result demonstrated that the fresh raw leaf had moisture content of 82.30 ± 0.42%, which were significantly (p<0.05) reduced by drying but not extraction and blanching. The protein content of the raw leaf was low (1.80 ± 0.10%). Extraction and blanching reduced the protein content, whereas drying increased the protein content significantly (p < 0.05) for raw dried leaf powder and blanched leaf products. The raw leaf contained vitamins A, B2, C and E, which were significantly reduced by extraction and blanching, but were concentrated by drying. Anti-nutrient contents of the raw leaf were low and were reduced to negligible levels by the processing techniques employed. Comparing the nutrient and chemical constituents with recommended dietary allowance (RDA) values, we found that the leaves contain an appreciable amount of nutrients, minerals, vitamins, proteins and phytochemicals and low degree of toxicants. These findings suggested that the treatment method employed in processing this leaf affected the proximate composition, and this should be considered in utilization of this leaf (and other leaves) product in various food and pharmaceutical formulations. Various heat processing techniques applied during the preparation of the processed products from Hibiscus rosa-sinensis leaves, caused adverse effects on the chemical composition of the processed leaf products. This was evident especially for the vitamins and minerals constitution of the processed products. More so, blanching and drying caused a significant reduction in the nutrients and anti-nutrient composition of the formulated samples. While the best processed samples were the dried powdered products, especially the RDLP, whereas the worst processed samples were the extracts, notably B2LE. It is recommended that other processing techniques such as freezing, solar and spray drying and ethanol extraction can also be applied in order to determine their effects on nutrient retention and anti-nutrient reduction on the plant leaves and compare it with the results of this study.

Author  Details:

Ifeyinwa Mirabel Eze

Department of Food Science and Technology, University of Nigeria, Nsukka 410001, Nigeria.

Daniel Don Nwibo

Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan, Institute of Medical Mycology, Graduate School of Medicine, Teikyo University, 359 Otsuka, Hachioji, Tokyo 192-0395, Japan and Department of Chemistry, University of Nigeria, Nsukka 410001, Nigeria.

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