**2.3 Evaluation of different methods to enhance the shelf life of oyster mushroom**

Drying is one of most broadly-practiced and oldest methods for preserving agricultural products to maintain the quality against decaying. It is done mainly in warmer areas such as the kitchen, near the stove or fireplace. These are used as heat sources and often drying is completed in the sun [26]. Three methods of oyster


#### **Table 15.**

*Packaging for button mushroom (*Agaricus bisporus *cv. NCS 100) washed with KMS (0.05%).*

#### *Postharvest Processing, Value Addition and Marketing of Mushrooms DOI: http://dx.doi.org/10.5772/intechopen.101168*

mushroom preservation/drying were evaluated under farmers conditions. The oyster mushroom (200 g) were first blanched at 75°C for 2 min in water. Thereafter, it was kept in two steeping solutions of 5% salt, 0.2% citric acid, 0.15% potassium meta bisulfite (KMS). In the second treatment, the same quantity of mushroom was dried using mechanical dryer at 45–50°C for 8 h. In third treatment, the same quantity of oyster mushroom was blanched and sun dried. Blanching with the use of hot water or steam is an important treatment applied after washing to inhibit tissue browning by inactivation of polyphenol oxidase and production of off flavors. It also removes trapped air and decreases weight losses to induce mushroom shrinkage [27]. These were then observed for color, texture and overall acceptability. In another experiment, freshly harvested fruiting body (500 g) of oyster mushroom (*Pleurotus florida*) was wrapped in muslin cloth and blanched in chemical solution (0.2% salt and 0.1% citric acid) at 75°C for 2 min. The fruiting bodies so obtained were sun dried and also dried in cabinet dryer at 60°C for 6.30 h. The freshly harvested fruiting body were also immerged in plain water and dried by sun as well as by cabinet dryer and the results are presented in **Table 16**.

Of three treatments assessed, the fresh oyster mushroom steeped in solutions of above chemicals with or without blanching were of good quality for the period of 105 days without much loss in color, texture and acceptability. Mushroom dried in a mechanical dryer at 45–50°C for 8 h. With blanching though changed in to blackish color but the loss in weight, brittleness and quality of the fruiting body remained least influenced followed by without blanching which were of excellent quality even up to 3 months of storage. The sun dried product when dipped in plain water and kept in pp. bags after 55 days at ambient temperature lost maximum weight of the fruiting body (3.12%) than any other treatment. The fruiting body became soft and developed brown color. Thus, it can be said that the oyster mushroom steeped in solutions of above chemicals and mechanically dried can be very well preserved for the period of 105 days without much influence on quality parameters. The increase in the drying temperature though helped to accelerate the drying rate but, high temperatures (70°C) are not generally recommended because, it causes browning in the samples and deteriorates the quality which are important from customer's viewpoint [28]. In another experiment conducted at AICMIP, Raipur center on different methods of drying of oyster mushroom exhibited drying by cabinet dryer


*NB. There was no rottage and insect attack within the storage period of 3 months.*

*\*+ Brittle, ++ Soft,*

*\*\*Quality parameters: + Pleasant flavor ++ Off flavor.*

#### **Table 16.**

*Studies on methods of drying of oyster mushroom (*Pleurotus florida*) on weight loss and other quality parameters.*

with and without blanching to be excellent as there was minimum reduction in weight, color was retained, fruit body was brittle and pleasant flavor was noticed within the period of 3 months of storage (**Table 16**). Other methods of drying were not that much effective as the per cent reduction in weight was more, fruit body started turning yellowish in color, became soft and developed off flavor. The results obtained on the preservation method had significant effects on the nutrient and mineral compositions of the mushroom samples [29]. In contrast to present investigation, the lowest weight values were obtained from the sundried mushroom samples while the highest value was obtained from the fresh samples by Jonathan et al. [30] which is difficult to be explained.
