Optimization of UV irradiation conditions for the vitamin D2-fortified shiitake mushroom (Lentinula edodes) using response surface methodology

Comparison of Ergosterol and Vitamin D2 in Mushrooms Agaricus bisporus and Cordyceps militaris Using Ultraviolet Irradiation Directly on Dry Powder or in Ethanol Suspension

Vitamin D deficiency is a severe worldwide health issue. Edible mushrooms are an excellent vitamin D₂ source and have gained popularity worldwide as a nutritional food. The objective of this study was to investigate the conversion efficiency of ergosterol to vitamin D₂ in Agaricus bisporus and Cordyceps militaris mushrooms under ultraviolet (UV) irradiation directly through dry powder or in ethanol suspension (1:20 g/mL, solid to liquid ratio). Several parameters of UV irradiation conditions such as the material form (dry powder or dry powder in ethanol suspension), exposure time (30, 60, or 120 min), wavelength type (UV-C, UV-B, or UV-A), wavelength combination (UV-C plus UV-B, UV-C plus UV-A, UV-B plus UV-A, or UV-C plus UV-B plus UV-A), and wavelength sequence (UV-C → UV-B, UV-C → UV-A, UV-B → UV-A, or UV-C → UV-B → UV-A), were optimized. Under the optimal UV irradiation conditions (dry powder in ethanol suspension irradiated with UV-C at 40 cm for 120 min), vitamin D₂ concentrations increased from not detectable to 72 μg/g (dw) in the A. bisporus dry powder and 1104 μg/g (dw) (about 15-fold increase) in the ethanol suspension. After UV irradiation, the vitamin D₂ concentration increased from undetectable to 57 μg/g (dw) in the C. militaris dry powder. In contrast, UV irradiation increased the concentration to 877 μg/g (dw) (about 15-fold higher) in the ethanol suspension. Comparison of the effect of various wavelength combinations showed that UV-C irradiation is more effective than UV-A or UV-B. Furthermore, when irradiated by UV-C at a 40 cm irradiation distance in the ethanol suspension, the increase in vitamin D₂ in A. bisporus and C. militaris mushrooms was time- or dose-dependent. The conversion rate of vitamin D₂ was low to undetectable under dry powder irradiation, but its ergosterol loss rate was higher than in ethanol suspension irradiation. The ergosterol loss rate in dry C. militaris mushrooms was higher than in the dry A. bisporus mushroom powder. Ultraviolet irradiation in ethanol suspension could greatly increase the vitamin D₂ concentration than directly on the dry powder and thus make edible mushrooms more practical as a natural vitamin D source for consumers after entirely removing the ethanol.

The future is bright: Biofortification of common foods can improve vitamin D status

Vitamin D deficiency is a global concern, linked to suboptimal musculoskeletal health and immune function, with status inadequacies owing to variations in UV dependent cutaneous synthesis and limited natural dietary sources. Endogenous biofortification, alongside traditional fortification and supplement usage is urgently needed to address this deficit. Evidence reviewed in the current article clearly demonstrates that feed modification and UV radiation, either independently or used in combination, effectively increases vitamin D content of primary produce or ingredients, albeit in the limited range of food vehicles tested to date (beef/pork/chicken/eggs/fish/bread/mushrooms). Fewer human trials have confirmed that consumption of these biofortified foods can increase circulating 25-hydroxyvitamin D [25(OH)D] concentrations (n = 10), which is of particular importance to avoid vitamin D status declining to nadir during wintertime. Meat is an unexplored yet plausible food vehicle for vitamin D biofortification, owing, at least in part, to its ubiquitous consumption pattern. Consumption of PUFA-enriched meat in human trials demonstrates efficacy (n = 4), lighting the way for exploration of vitamin D-biofortified meats to enhance consumer vitamin D status. Response to vitamin D-biofortified foods varies by food matrix, with vitamin D₃-enriched animal-based foods observing the greatest effect in maintaining or elevating 25(OH)D concentrations. Generally, the efficacy of biofortification appears to vary dependent upon vitamer selected for animal feed supplementation (vitamin D₂ or D₃, or 25(OH)D), baseline participant status and the bioaccessibility from the food matrix. Further research in the form of robust human clinical trials are required to explore the contribution of biofortified foods to vitamin D status.

UV induced conversion during drying of ergosterol to vitamin D in various mushrooms: Effect of different drying conditions

BACKGROUND

Mushrooms are increasingly popular around the world as a nutritional food which is an excellent source of vitamin D2. Although natural mushrooms often contain very little vitamin D2 as many are grown in the dark, they are rich in ergosterol, a precursor to vitamin D2. Ergosterol can be converted to vitamin D2 under ultraviolet radiation. Due to the high water content of fresh mushroom, its quality deteriorates rapidly after harvest, and drying is the most commonly used technology to extend the shelf life. The vitamin D2 content of dried mushrooms depends on the drying conditions used.

SCOPE AND APPROACH

In this review, the chemistry of the photo-conversion process of ergosterol to vitamin D2 under ultraviolet radiation is introduced. The ergosterol and vitamin D contents in different mushroom varieties are discussed. The effects of several drying methods and the influence of different drying conditions are reviewed.Key findings and conclusions: Thermal drying in the presence of UV has been proven to convert ergosterol into vitamin D and enhance the nutritional content of all types of edible mushrooms. Solar drying, hot air drying, freeze drying, microwave drying and infrared drying can be used for mushrooms drying under selected operating conditions. A critical evaluation of published literature demonstrates the importance of applying appropriate drying methodology to maximize the nutritional value of various types of edible mushrooms.

Ultraviolet Irradiation Increased the Concentration of Vitamin D2 and Decreased the Concentration of Ergosterol in Shiitake Mushroom (Lentinus edodes) and Oyster Mushroom (Pleurotus ostreatus) Powder in Ethanol Suspension

Vitamin D deficiency is a serious global health problem. Edible mushrooms are a good source of vitamin D for human health. The objective of this experiment was to investigate the efficiency of converting its precursor ergosterol to vitamin D₂ in shiitake mushroom (Lentinus edodes) and oyster mushroom (Pleurotus ostreatus) powder in ethanol suspension under ultraviolet (UV) irradiation. UV irradiation conditions were optimized for several parameters, such as material form, wavelength, wavelength combination, and exposure time. Under the optimal conditions, UV irradiation increased the concentrations of vitamin D₂ from undetectable to 40.59 ± 1.16 μg/g (dw) in dry shiitake mushroom powder and to 677.28 ± 40.42 μg/g (dw) (an approximately 16.69-fold increase) in ethanol suspension. The concentration of vitamin D₂ increased from undetectable to 23.71 ± 5.72 μg/g (dw) in the dry oyster mushroom powder upon UV irradiation, whereas UV irradiation increased the concentration to 275.32 ± 48.45 μg/g (dw) (an approximately 11.61-fold increase) in the ethanol suspension. Comparing the effects of varying combinations of wavelengths showed that irradiation with UV-A, UV-C, or a combination of both is more effective than UV-B irradiation. In addition, the increase in vitamin D₂ in shiitake mushrooms irradiated by UV-C was time-dependent, that is, dose-dependent. Nevertheless, the increase rates decreased with time. The concentration of ergosterol decreased with the increase in vitamin D₂, but ergosterol was only partially converted to vitamin D₂, whereas most of the ergosterol was probably UV-degraded. Exposure to ultraviolet light in ethanol suspension offers an effective way to increase the concentration of vitamin D₂ and thus improve the nutritional value of edible mushrooms, as well as make them more functional as a source of vitamin D to improve the consumer health.

Development of high yielding strain of Pleurotus tuber-regium: fructification, nutritional and phylogenetic studies

Mushrooms are nutritionally rich, healthy and medicinal. Pleurotus tuber-regium (Fr.) is one of the nutritious medicinal mushroom found in the tropics and subtropics, but with history of slow growth and low sclerotia yield. In this study, mutants were created by mycelia exposure to ultraviolet irradiation (at a wavelength of 254 nm and a distance of 45 cm), for 3 h and sub-cultured at 30 min interval. The DNA from the wild and mutant strains were extracted, PCR amplified and sequenced. A phylogenetic tree was constructed to show the degree of similarity and differences between the wild and the mutant strains. Fructification studies were conducted on Rhodes grass straw and sawdust to determine the viability of the mutant strains and any nutritional improvement. The wild strain of P. tuber-regium and mutant produced at 30 min (Pt30) cultivated on sawdust and Rhodes straw, yielded sclerotia with biological efficiency of 8.8 and 47.6% respectively. Proximate analysis of the sclerotium showed that the mutant, Pt30, had improved nutritional compositions compared to the wild strain with a total non-structural carbohydrate concentration of 2.41 g as against 0.93 g. Conclusively in this study, better strains of P. tuber-regium were produced with faster growth rate, higher mycelia ramification rate on lignocellulosic substrate and a higher sclerotia yield than the wild P. tuber-regium. It was also established that mutagenesis is capable of improving P. tuber-regium for a successful commercial venture in sclerotia production.