Effect of processing and storage on the retention of flavour compounds in Piper nigrum L. and Aframomum danielli spice sample
Date
2018-07
Authors
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Publisher
Federal University of Technology, Owerri
Abstract
Effects of processing and storage on the retention of flavour compounds in Piper nigrum L(‘black pepper’) and Aframomum danielli seeds spice samples was studied. Mature berries of Piper nigrum L. and pods of Aframomum danielli were procured from point of harvest and subjected to post-harvest treatment and dried respectively. Dried spice seeds were pulverize into powder prior to extraction of flavour compounds with six different solvents. The solvent extraction process was at 1:5w/v ratio of spice powder to solvent and the extract was vaporized to obtain 1:1w/v flavour extract from each solvent for preliminary investigation of flavour constituents. Three processing methods were applied for each spice: (i) pulverized sample, (ii)extract with aqueous 40% ethanol sample and (iii) ethanol extract-coated on suitable carriers(potato grits and rice grits). The pulverized and 40% ethanol extract were stored in amber coloured glass bottles while extract on suitable carriers were packaged in high density polyethylene bags. Each sample was stored at ambient temperature (30+ 3o C) for six months and analyzed at intervals. GC-MS was used to determine the chemical constituents and to monitor the flavour profile during storage. The results of moisture content, specific gravity, phytochemicals and flavour compounds in solvent extract samples were significantly (p<0.05) varied. Specific gravity of absolute ethanol flavour extract was 0.784 in Piper nigrum L. and 0.612 in Aframomum danielli and were significantly higher (p<0.05) than other solvent samples. In Piper nigrum L. n-hexane flavour extract showed 86 GC-MS peaks and 30 Major Flavour Principles (MFPs). This was followed by acetone extract with 78 GC-MS peaks and 26 MFPs. GC-MS peaks of 56 with 18 MFPs in absolute ethanol, 59 GC-MS peaks with 25MFPs in 40% ethanol extract, 42 GC-MS peaks with 20 MFPs in methanol and water extract had the least 5 peaks and 3MFPs. Piperine was the high major flavour principles (MFPs) in Piper nigrum L. flavour and the values ranged from 2.43% in hexane extract to 17.50% in ethanol extract. However 10 GCMS peaks and 8 MFPs were found in absolute ethanol extract of Aframomum danielli, 9 GC-MS peaks and 7 MFPs in 40% ethanol extract sample, 22 GC-MS peaks and 6 MFPs in methanol sample, 28 GC-MS peaks and 7 MFPs in acetone flavour extract, 84 GC-MS peaks and 12 MFPs in hexane flavour extract and none in water extract of Aframomum danielli. The highest major flavour principle ‘MFPs’ of Aframomum danielli solvent extracts was eucalyptol with values ranging from 20.53% to 62.05%. Percentage retention (PR) of core volatile flavour principles in extract coated in suitable carriers in both spices reduced when the ratios of coating materials (rice grits and potato flour) increased in the encapsulated samples. Furthermore, the percentage retention of core volatile flavour principles in spice products samples studied varied at 6months storage. However 40% ethanol extract of Piper nigrum product sample (PP-EB) had the 91.31%
piperine retention higher than other spice products samples in Piper nigrum while pulverized of Aframomum danielli product sample (AFD-PB) showed 83.46% highest eucalyptol retention among Aframomum danielli spice products. Sensory evaluation identified 5 and 8 sensory attributes of Piper nigrum and Aframomum danielli spice flavour product samples respectively. Pearson correlation value of 0.927 in Piper nigrum and 0.671 in Aframomum danielli for flavour pungency was the highest among other sensory attributes to overall acceptability. The total viable counts of fungi and bacteria were higher in raw spices than processed powder. Initial bacterial load was 1.21 x 109 cfu/g in black pepper berries and 7.8 x 108 cfu/g in Aframomum danielli raw seeds. These reduced to 0.9 x 103 cfu/g and 1.21 x 103 cfu/g pulverized spice powder.
Description
This Doctoral thesis is for the award of Doctor of Philosophy Degree in Food Science and Technology
Keywords
Aframomum danielli, eucalyptol, flavour, flavour retention, Piper nigrum L., phytochemical, piperine, pungency, potato grits and rice grits, Department of Food Science and Technology
Citation
Adedokun, I. I. (2018). Effect of processing and storage on the retention of flavour compounds in Piper nigrum L. and Aframomum danielli spice sample (Unpublished Doctoral Thesis). Federal University of Technology, Owerri, Nigeria