Effect of processing and storage on flavour retention of xylopia aethiopica and curcuma longa specie samples
Date
2018-07
Authors
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Journal ISSN
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Publisher
Federal University of Technology, Owerri.
Abstract
The main objective was to determine the effect of processing and storage on flavour retention of Xylopia aethiopica and Curcuma longa. Spice products were processed into powders and six different solvents (absolute ethanol 98.99%, 40% ethanol, methanol, acetone, n-Hexane and water) were used to extract the bioactive compounds in the spices. The spices were separately processed into six different spice products that included spice powder, liquid spice extract and four encapsulated spice samples with wheat and yam grits as carriers at the ratios of 1:2 and 1:3 spice extract to carrier.They were packaged in amber coloured plastic bottles and stored at ambient temperature (28±30 C) for six months. The essential oils obtained by different solvent extractions from spiceswere analysed by gas chromatography-mass spectrometry (GCMS) while the curcumin content of the C. longa for the different solvent extracts were analysed with Ultra-fast liquid chromatography (UFLC). Microbiological analysis were conducted on the fresh and dried ground spices for initial microbial load determination. Sensory evaluation were also carried out on the spice samples. The results of phytochemicals on the two spices identified the presence of alkaloids, flavonoids, phytic acid, saponins, tannins and oxalates. Different compounds were obtained from the different solvent extracts of X. aethiopica but the most predominant common flavour compounds found were two monoterpenes and one diterpene which included beta-pinene (15.48% in absolute ethanol, 20.28% in 40% ethanol, 8.11% in acetone, 14.03% in methanol but not detected in n-Hexane and water extracts), beta-phellandrene (18.93% in absolute ethanol, 23.93% in 40% ethanol, 21.54% in methanol, 7.38% in acetone, 12.09% in n-Hexane and 4.29% in water) and andrographolide (9.66% in absolute ethanol, 8.06% in 40% ethanol, 7.67% in methanol, 7.29% in acetone, 4.20% in n-Hexane and was not detected in the water extract). The major compounds identified by GC-MS analysis of C. longa were sesquiterpenes (40.55%), fatty acids (27.16%), diarylheptanoid (12.02%) and steroids (4.35%). The following curcumin concentrations were obtained in the different solvents extracts; absolute ethanol (53.27%), 40% ethanol (10.74%), methanol (12.46%), acetone (14.15%), n-Hexane (3.77%) and water (2.29%). At the end of the 6 months ambient storage of X. aethiopica spice products, the 40% ethanol extract had the highest concentration of beta-phellandrene with 19.56%, the concentration of betaphellandrene was significantly (p<0.05) higher when in wheat grit carrier (13.54%) at ratio 1:2 after 6 months compared to when it was in yam grit carrier (9.77%) at ratio 1:2. However, the 1:2 ratio retained more than the 1:3 ratio in both carriers. But in C. longa spice products, at the 6th month of storage the spice powder had the most concentration of Curcumin with 39.67%, the yam grits carrier retained more than the wheat grits while the 1:2 ratio retained more than 1:3 ratio in both carriers. The total fungal counts for C. longa ranged from 2.0 x 105 cfu/g in the ground sample to 3.2 x 108 cfu/g in the raw sample and 2.20 x 105 cfu/g in the ground X. aethiopica sample to 5.1 x 108
cfu/g in the raw sample. The common microflora of the spices were; Saccharomyces cerevisiae, Enterococcus, Bacillus, Lactobacillus and Streptococcus for C. longa and Saccharomyces cerevisiae, Enterococcus, Penicilliumnotatum, Bacillus, Lactobacillus, Staphylococcus and E. coli for X. aethiopica The scores of the sensory quality attributes of the spices showed that the 40% ethanol extract was the most acceptable sample. The sample was recommended for a greater number of different foods and drinks such as rice, meat, sauce, tea, akamu/pap, baked products, yoghurt, alcoholic and non-alcoholic beverages for C. longa and meat, porridge, pepper soup, Igbo soup, Yoruba soup, Hausa soup and alcoholic beverages for X. aethiopica.
Description
This thesis is for the award of Doctor of Philosophy (PhD.) in Food Chemistry and Nutrition Option
Keywords
Curcumalonga, encapsulation, flavour principle, grits, liquid flavour extract, microbial load, sensory evaluation, xylopia aethiopica, Department of Food Science and Technology
Citation
Ibe, C. (2018). Effect of processing and storage on flavour retention of xylopia aethiopica and curcuma longa specie samples [Unpublished Doctoral Thesis]. Federal University of Technology, Owerri, Nigeria