Effect of Pretreatments and Drying Temperatures on the Quality of Dried Pleurotus Mushroom Spp.

Abstract

This study was carried out to evaluate the effect of pretreatments prior drying as well as drying temperature on quality of the dried mushroom. Rehydration ratio and color of the dried product are the most effective parameter for judging and evaluating the drying process. Pleurotus ostreatus and Pleurotus eryngii samples were pretreated by different solutions (NaCl, citric acid and sodium metabisulfite) at room temperature and at 96± 2 o C. Pretreated and control mushroom samples were dried by hot air at 50, 60 and 70 o C until reached to constant weight. The dried product was evaluated immediately after drying. P. ostreatus required from 7-12 hr, while P. eryngii required 6.5-11 hr to reach moisture content around 7% depending on pretreatment and drying temperature. Control sample dried by using any tested drying temperature recorded the highest rehydration ratio compared to other pretreated samples dried at the same drying temperature. Also, steeped dried samples had higher rehydration ratio than blanched ones. Samples steeped in sodium metabisulfite (SMS) prior drying had the lowest browning index, while those blanched in NaCl or citric acid had the highest browning index values. Drying process caused a considerable decrement in protein content and a severe reduction in total microbial counts of mushroom samples. Sensory evaluation revealed that control and samples steeped in SMS or NaCl prior drying at 50 o C got higher scores than the others. According to the results obtained it could be clearly concluded that, steeping P. ostreatus and P. eryngii samples in NaCl, citric acid or Sodium metabisulfite (0.1% each at room temperature) for 10 min. prior drying at 50 o C prevented browning especially with SMS. Also, steeping treatment resulted satisfactory rehydration ratio for dried products even they were lower than the untreated (control) sample.

Impact of Pre-drying Treatments on Antioxidant Activities and Quality of Dried Golden Oyster Mushroom (Pleurotus citrinopileatus)

“…Maray et al [22] revealed that blanching at 90 o C for 3 min and immersing in a 0.5% citric acid for 30 min lowered the BI of dried oyster mushrooms (Pleurotus ostreatus). The result from this study was in agreement with the findings of Hassan and Medany [23], who showed that dried Pleurotus ostreatus and Pleurotus eryngii steeped in 0.1% Na2S2O5, 0.1% NaCl, and 0.1% citric acid for 10 min had lower BI than that of untreated mushrooms. Lower BI in blanched, NaCl, and citric acid-treated mushrooms can probably be related to inactivation of browning enzymatic reactions.…”

Influence of different drying methods and cold storage treatments on the postharvest quality and nutritional properties of P. ostreatus mushroom

“…Likewise, protein content of P. tuoliensis stored at 4 °C decreased with increasing of storage time (Li et al, 2021). In general, the drying process causes a significant reduction in protein content of mushrooms (Hassan and Medany, 2014). The lowest protein content in P. eryngii was found in microwave drying among different drying methods (Lüle, 2014), which was consistent with our findings.…”

Systematic Review: Heat Treatments on Phenolic Content, Antioxidant Activity, and Sensory Quality of Malaysian Mushroom: Oyster (Pleurotus spp.) and Black Jelly (Auricularia spp.)

“…According to Nöfer et al (2018), prolonged drying time and high temperatures may degrade the mushroom aroma. According to Hassan and Medany (2014), pre-treatment of P. ostreatus and P. eryngii with 0.1% sodium metabisulfite at room temperature improved mushroom color and microbiological characteristics, while also retaining its nutrients. The highest rehydration ratio was found in the untreated mushrooms.…”

“…Additionally, soaking mushrooms in 0.1% NaCl or 0.1% citric acid for 10 min at room temperature produced acceptable results, though they were not as good as those treated with sodium metabisulfite. Hassan and Medany (2014) found out blanching as a pre-treatment is ineffective for enhancing the quality of dried mushrooms. Not just them, Argyropoulos et al (2011b) in the research concluded that blanching can cause undesired color and texture of mushrooms (hardens), while also inhibiting enzyme activity and reducing microbial populations.…”