94-8 |
|
V. J. JASINGHE and C. O. Perera. Dept. of Chemistry, National Univ. of Singapore, Food Science & Technology Programme, Science Dr. 4, S3-06, Singapore, 117543, Singapore Vitamin D deficiency is an unrecognized epidemic among the elderly population. Mushrooms are considered a delicacy highly accepted by vegetarians as well as non-vegetarians, and are abundant in ergosterol, the precursor of vitamin D2. Our objective was to determine the effect of UV-B irradiation and the positioning of the gills and cap to the UV source, on the conversion of ergosterol to vitamin D2 in mushrooms. Lyophilized mushroom samples were analyzed by HPLC according to a modified AOAC method. Vitamin D2 and ergosterol were determined by comparing the retention times of standards obtained and quantification was done using a calibration curve. The ergosterol content in different parts of mushrooms varied significantly (p<0.05), while Vitamin D2 was absent in cultivated mushrooms studied. The highest ergosterol content was found in button mushrooms (7.80 ± 0.35 mg/g DM) while the lowest was in enoki mushrooms (0.68 ± 0.14 mg/g DM). The conversion of ergosterol to vitamin D2 was higher when gills rather than the outer caps were exposed to UV irradiation. The lowest conversion of ergosterol to vitamin D2 (12.48 ± 0.28 µg/g DM) was for button mushrooms while the highest value (45.10 ± 3.07 µg/g DM) was for oyster mushrooms. The optimum moisture content of mushrooms and temperature for this conversion was around 78 % WB and 35 oC respectively. Iirradiating for 1 h each of gills and caps was found to be the optimum for this conversion. Irradiating both sides of oyster mushrooms for one-hour resulted in more than doubling the value of vitamin D2 (96.86 ± 5.73 µg/g DM) compared to when only one side was irradiated The results strongly suggest that vitamin D2 content in mushrooms can be increased remarkably by UV-B irradiation. Further studies on bioavailability of vitamin D2 from UV-irradiated mushrooms are underway.
Session 94, Food Chemistry: Chemical effects of food processing, preservation and formulation
|