Recent advances and role of melatonin in post-harvest quality preservation of shiitake (Lentinula edodes)

Shiitake mushrooms are renowned for their popularity and robust nutritional value, are susceptible to spoilage due to their inherent biodegradability. Nevertheless, because of their lack of protection, these mushrooms have a short shelf life. Throughout the post-harvest phase, mushrooms experience a persistent decline in quality. This is evidenced by changes such as discoloration, reduced moisture content, texture changes, an increase in microbial count, and the depletion of nutrients and flavor. Ensuring postharvest quality preservation and prolonging mushroom shelf life necessitates the utilization of post-harvest preservation techniques, including physical, chemical, and thermal processes. This review provides a comprehensive overview of the deterioration processes affecting mushroom quality, covering elements such as moisture loss, discoloration, texture alterations, increased microbial count, and the depletion of nutrients and flavor. It also explores the key factors influencing these processes, such as temperature, relative humidity, water activity, and respiration rate. Furthermore, the review delves into recent progress in preserving mushrooms through techniques such as drying, cooling, packaging, irradiation, washing, and coating.

Volatile compounds and aroma characteristics of mushrooms: a review

Mushrooms are popular due to their rich medicinal and nutritional value. Of the many characteristics of mushrooms, aroma has received extensive attention and research as a key determinant of consumer preference. This paper reviews the production, role and contribution of common volatile compounds (VCs) in wild and cultivated mushrooms, and explores the methods used to characterize them and the factors influencing aroma. To date, more than 347 common VCs have been identified in mushrooms, such as aldehydes, ketones, alcohols and sulfur-containing compounds. Extraction and identification of VCs is a critical step and combining multiple analytical methods is an effective strategy in mushroom aroma studies. In addition, the VCs and the aroma of mushrooms are affected by a variety of factors such as genetics, growing conditions, and processing methods. However, the mechanism of influence is unknown. Further studies on the production mechanisms of VCs, their contribution to aroma, and the factors influencing their formation need to be determined in order to fully elucidate aroma and flavor of mushrooms.

Using Science and Technology to Unveil The Hidden Delicacy Terfezia arenaria, a Desert Truffle

Terfezia arenaria is a desert truffle native to the Mediterranean Basin region, highly appreciated for its nutritional and aromatic properties. Despite the increasing interest in this desert truffle, T. arenaria is not listed as an edible truffle authorized for trade in the European Union. Therefore, our objective was to showcase T. arenaria's nutritional and chemical composition and volatile profile. The nutritional analysis showed that T. arenaria is a good source of carbohydrates (67%), proteins (14%), and dietary fibre (10%), resulting in a Nutri-Score A. The truffle's volatile profile was dominated by eight-carbon volatile compounds, with 1-octen-3-ol being the most abundant (64%), and 29 compounds were reported for the first time for T. arenaria. T. arenaria's nutritional and chemical compositions were similar to those of four commercial mushroom and truffle species, while the aromatic profile was not. An electronic nose corroborated that T. arenaria's aromatic profile differs from that of the other four tested mushroom and truffle species. Our data showed that T. arenaria is a valuable food resource with a unique aroma and an analogous composition to meat, which makes it an ideal source for plant-based meat products. Our findings could help promote a sustainable future exploitation of T. arenaria and ensure the quality and authenticity of this delicacy.

Effects of Drying Process on the Volatile and Non-Volatile Flavor Compounds of Lentinula edodes

In this study, fresh Lentinula edodes was dehydrated using freeze-drying (FD), hot-air drying (HAD), and natural drying (ND), and the volatile and non-volatile flavor compounds were analyzed. The drying process changed the contents of eight-carbon compounds and resulted in a weaker “mushroom flavor” for dried L. edodes. HAD mushrooms had higher levels of cyclic sulfur compounds (56.55 μg/g) and showed a stronger typical shiitake mushroom aroma than those of fresh (7.24 μg/g), ND (0.04 μg/g), and FD mushrooms (3.90 μg/g). The levels of 5′-nucleotide increased, whereas the levels of organic acids and free amino acids decreased after the drying process. The dried L. edodes treated with FD had the lowest levels of total free amino acids (29.13 mg/g). However, it had the highest levels of umami taste amino acids (3.97 mg/g), bitter taste amino acids (6.28 mg/g) and equivalent umami concentration (EUC) value (29.88 g monosodium glutamate (MSG) per 100 g). The results indicated that FD was an effective drying method to produce umami flavor in dried mushrooms. Meanwhile, HAD can be used to produce a typical shiitake mushroom aroma. Our results provide a theoretical basis to manufacture L. edodes products with a desirable flavor for daily cuisine or in a processed form.

Impact of post-harvest processing or thermal dehydration on physiochemical, nutritional and sensory quality of shiitake mushrooms

Shiitake mushrooms are one of the most popular and highly consumed mushrooms worldwide both in fresh and dry forms. However, it rapidly starts losing its quality immediately after harvest which necessitates processing and/or proper storage before being distributed. However, the processes used for preserving other mushrooms (e.g., Agaricus) become unviable for shiitake due to its uniqueness (higher respiration rate, varied biochemicals, growth, etc.) which demands individual studies on shiitake. This review starts by listing the factors and their interdependence leading to a quality decline in shiitake after harvest. Understanding well about these factors, numerous post-harvest operations preserve shiitake as fresh form for a shorter period and as dried forms for a longer shelf-life. These processes also affect the intrinsic quality and nutrients of shiitake. This review comprehensively summarizes and discusses the effects of chemical processing (washing, fumigation, coating, and ozone), modified atmosphere packaging (including irradiation) on the quality of fresh shiitake while discussing their efficiency in extending their shelf-life by inhibiting microbial spoilage and deterioration in quality including texture, appearance, nutrients, and favor. It also reviews the impact of thermal dehydration on the quality of dried shiitake mushrooms, especially the acquired unique textural, nutritional, and aromatic properties along with their merits and limitations. Since shiitake are preferred to be low-cost consumer products, the applicability of freeze-drying and sophisticated novel methodologies, which prove to be expensive and/or complex, are discussed. The review also outlines the challenges and proposes the subsequent future directives, which either retains/enhances the desirable quality in shiitake mushrooms.