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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