Parameter optimization of high O2 dynamic controlled atmosphere storage of agaricus bisporus

Abstract: Agaricus bisporus is highly perishable due to its thin protective structure, which could protect it from physical and microbial attack. Meantime, the high metabolism of white mushroom could accelerate the progress of senescence including water loss, cap opening and enzymatic browning, and damage its nutrition value and commercial quality seriously. It only has a short shelf life of 3-4 days at ambient temperature after harvest. Thus, an effective storage method plays an important role in mushroom industry. In this study, dynamic controlled atmosphere (DCA) was used to extend the shelf life of white mushroom. Several studies had confirmed that DCA performed well in some fruits and vegetables storage. Compared with traditional controlled atmosphere, DCA is a technique that periodically changes the ambient gas of products. It is designed to provide an optimal storage condition in different storage periods, aiming at improving the quality of products and preventing the development of physiological disorders. In this study, white mushrooms were stored at (2±1) ℃ and the first-stage gas (100% O2, 90% O2+10% CO2, 80% O2+20% CO2, 70% O2+30% CO2), transaired time (2nd, 3rd, 4th and 5th day ) and second-stage gas (100% O2, 90% O2+10% CO2, 80% O2+20% CO2, 70% O2+30% CO2 ) were determined as a single factor on the effect of ΔE, firmness and sensory value. Meantime, white mushroom storage conditions were optimized for orthogonality, and the physiological and biochemical quality changes under optimal storage condition were obtained during storage of white mushroom by using conductivity meter, O2/CO2 analyzer and other equipments. Under the condition of a single factor, the ΔE, firmness and sensory value were determined and the appropriate first-stage gas of 100% O2, 90% O2+10% CO2, 80% O2+20% CO2, transaired time of 2nd, 3rd and 4th day and second-stage gas of 100% O2, 90% O2+10% CO2, 80% O2+20% CO2 were employed in orthogonality. The best condition of orthogonal optimization was 100% O2 first-stage gas, transaired time 3rd day and 80% O2+ 20% CO2 second-stage gas. The ΔE, firmness and sensory value in this condition was 19.40, 6.84×105 Pa and 9.52 respectively. The results showed that the first-stage gas whose O2 fraction above 80% could inhibit the increase of ΔE significantly (P<0.05). The 80% O2+20% CO2 second-stage gas treatment retained significant (P<0.05) lower ΔE and higher firmness than that of other treatments. The transaired time had no significant effect on the quality of mushrooms (P>0.05). During storage of orthogonal optimization, compared with static controlled atmosphere (SCA), DCA could inhibit the decrease of soluble protein content of white mushroom significantly (P<0.05) and retain its good nutrient quality. Meantime, it suppressed the respiration rate and retained certain cell membrane integrity, then further slowed down the senescence of white mushrooms. In addition, white mushroom stored in DCA had moderate peroxidase (POD), higher ascorbate peroxidase (APX) and lower polyphenol oxidase (PPO) activity than those stored in SCA, indicating that DCA is potential to slow down the progress of enzymatic browning. In this study, DCA treatment preserved relative good quality of white mushroom during storage and extended its storage time to 28 d, confirming that DCA is a suitable method for white mushroom storage and a potential technique for fruits and vegetables storage.