Effect of pulsed UV light irradiation on vitamin D2 content and physiologically active substances of Agaricus bisporus, Flammulina velutipes, Lentinula edodes and Cordyceps militaris- Fermented Buckwheat

• Main Authors: Chiu, Li-Hui, 邱麗惠
• Other Authors: Tsai, Shu-Yao
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/30092399903305445089

碩士 === 亞洲大學 === 保健營養生技學系 === 102 === Agaricus bisporus, Flammulina velutipes, Lentinula edodes and Cordyceps militaris are important edible and medicinal mushrooms in Taiwan. These mushrooms contain a variety of nutrients and bioactive components such as vitamin, carbohydrate, dietary fiber, protein, ergosterol, amino acid and umami constituents acknowledged to be beneficial for human’s health. Compared with continuous UVB light method, pulsed light irradiation offers greater advantages owing to its non-thermal technology for the rapid inactivation of microorganisms in foods using a broad spectrum (200-1000 nm) lamp along with high intensity pulses that delivers high peak power energy in seconds. Vitamin D has been categorized into two distinct forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D2 is synthesized from the fungal ergosterol through exposure to ultraviolet light. Therefore, in some mushroom cultivation techniques, pulsed light is typically employed to optimize vitamin D2 contents in some mushrooms due to its broadband spectrum encompassing UVA, UVB, and UVC. Besides, the application of pulsed light for vitamin D2 enhancement in some fresh mushrooms is proven to be more attractive due to its ability to decrease irradiation time and browning effects. This study is aimed to discover the optimum dose of pulsed light irradiation in A. bisporus, F. velutipes and L. edodes, by applying 0, 10, 30, 50 pulses, while the temperature control was set at 10, 30 and 50°C. Furthermore, A. bisporus and L. edodes were divided into three groups: whole fruiting bodies, 0.7cm sliced fruiting bodies and powdered form, while F. velutipes was divided into two groups: whole fruiting bodies and powdered form. The whole fruiting bodies and sliced fruiting bodies were classified as the fresh irradiated samples, whereas, the powder was grouped as the dry irradiated samples. Furthermore, discover of pulsed light irradiation in C. militaris buckwheat using common buckwheat as base, by applying 0, 10, 30, 50 pulses. C. militaris buckwheat were divided into three groups: common buckwheat, fresh C. militaris buckwheat and dry C. militaris buckwheat. The radiant energy was adjusted at 4.208 J/ cm2/ per pulse and sample was put at a distance of 4.7 cm from the lamp to obtain the optimum enhancement of vitamin D2 contents. The analysis of physiological activity substances, antioxidant properties and non-volatile flavor components of A. bisporus, F. velutipes, L. edodes and C. buckwheat were conducted. According to the results, the contents of vitamin D2 increased in this following order: continuous pulsed light irradiation > indirect pulsed light irradiation, sliced fruiting bodies > fruiting body and 50 pulses > 30 pulses > 10 pulses > unirradiated (0 pulse) samples. Briefly, fresh irradiation on whole fruiting bodies successfully achieved the increasing contents of vitamin D2 in three mushrooms as shown by F. velutipes (2.34~102.07 μg/g) > A. bisporus (nd~52.68 μg/g) > L. edodes (nd~45.31 μg/g). Moreover, the contents of vitamin D2 in sliced fruiting bodies of the two mushrooms were also significantly increased in the order of A. bisporus (nd~99.62 μg/g) > L. edodes (1.28~83.28 μg/g). It is also worth noting that in dry irradiation treatment, the contents of vitamin D2 in all mushrooms were rapidly enhanced as can be seen in this sequence: A. bisporus (nd~229.99 μg/g) > L. edodes (nd~172.25 μg/g) > F. velutipes (4.29~122.03 μg/g). On the contrary, there was no impact on the contents of ergosterol after irradiation on all mushrooms. Optimum dose by 50 PL irradiation on vitamin D2 contents of fresh C. buckwheat reached 22.50 μg/g, but common buckwheat contain very little vitamin D2 levels. In regard to physiologically active substances, the contents of water- soluble polysaccharides of mushrooms under pulsed light irradiation had shown significant increments, even though total phenol and flavonoid contents were slightly decreased. Pertaining to antioxidant activity, the reducing power of ethanolic extracts from mushrooms after pulsed light irradiation demonstrated that EC50 value of the whole fruiting bodies performed more optimum than sliced fruiting bodies of A. bisporus and L. edodes. Based on the scavenging abilities on 2,2-diphenyl-1- picrylhydrazyl radicals (DPPH) and chelating abilities on ferrous ions on ethanolic extracts of the mushrooms after pulsed light irradiation, EC50 value of A. bisporus obtained the most optimum value among all. The contents of water- soluble polysaccharides of C. buckwheat under pulsed light irradiation had shown significant increments. The reducing power of ethanolic extracts from C. militaris buckwheat after pulsed light irradiation demonstrated that EC50 value of the unirradiated sample performed more optimum than irradiated buckwheat and fresh C. militaris buckwheat. The scavenging abilities on DPPH on ethanolic extracts of the common buckwheat obtained the highest value among all, but chelating abilities on ferrous ions on ethanolic extracts of the common buckwheat showed the lowest value. The analysis of non-volatile taste components in these mushrooms including soluble sugars, free amino acid and flavor 5'-nucleotides revealed that soluble sugar contents comprising ribose (6.63~6.81 mg/g), fructose (6.54~8.55 mg/g), mannitol (229.90~275.52 mg/g) and myo-inositol (10.00~13.25 mg/g) were found in A. bisporus; fructose (219.73~259.27 mg/g), myo-inositol (8.02~8.99 mg/g) and sucrose (52.58~59.67 mg/g) were found in F. velutipes; and fructose (42.73~55.75 mg/g), mannitol (98.49~107.84 mg/g), myo-inositol (nd~14.44 mg/g) and trehalose (nd~4.60 mg/g) were found in L. edodes. Contents of monosodium glutamate-like and sweet components were substantially high in F. velutipes (3.26~7.5 mg/g) and A. bisporus (34.16~37.45 mg/g), respectively. In conclusion, the increasing exposure rate to pulsed light highly induced the enhancement of the vitamin D2 contents of these three mushrooms and C. militaris buckwheat. In addition, it is noticeable that not only do A. bisporus, F. velutipes and L. edodes contain abundant polysaccharides, umami taste and essential amino acid, but they also conceive the food flavoring substances. Overall, this study had attested that pulsed light irradiation can be considered as one of the effective pathways to greatly boost the vitamin D2 contents in A. bisporus, F. velutipes L. edodes and C. militaris buckwheat. Pulsed light irradiation on edible mushrooms can be one of the potential weapons to overcome the global issue in vitamin D2 deficiency. At last, it is also suggested that the effects of pulsed light irradiation in some other compounds and substances in mushrooms can be a fruitful area of research in the near future.