A Study On The Processing Technology And Shelf Life Of An Instant Tremella Fuciformis Product

The long cooking time,high sugar content,slow rehydration,rate,hard texture and potential of package damage of the instant,dried Tremella fuciformis products on the market attribute to its limited sales.These aspects were researched to improve Tremella fuciformis products' quality in this thesis.This thesis represents a systematic study on low sugar products to improve these aspects in 3 steps.Firstly,balancing polysaccharides leaching and product's sensory quality,the pre-dehydration processing conditions were optimized.Secondly,Aw and factors affecting it in the dried Tremella fuciformis product were analyzed for dehydration evaluation.Lastly,Aw was applied as a key index,as well as microwave treatment,to achieve a maximized shelf life for the reduced-sugar,instant,dried Tremella fuciformis product.Meanwhile an experimental study on the effect of Tremella fuciformis product on mice immune function was done.The results were as follows:(1)With a minimum loss of polysaccharides and the most desirable sensory quality, a combination of the pre-dehydration processing conditions was determined:soaking with pH 6 water at 30℃for 15min followed by steam cooking for 8 min under 0.1MPa.(2)With 20%polydextrose and 30%sucrose mixture a reduced(i.e.,40-45%)sugar Tremella fuciformis product with the same desirable Aw level was obtained.(3)Aw was found to be the key factor affecting the quality of the product.Salt, sugar and moisture content had marked impact on the product's Aw in a second order f unction:Y=0.73694-0.03867X₁-0.0399X₂+0.08409X₃-0.03869X₃²(where,Y= Aw,X₁, X₂ and X₃=salt,sugar and moisture content,respectively).(4)Aw had a significant effect on microbial growth in the dried Tremella fuciformis product.At Aw=0.645～0.721,microorganisms remained largely dormant during storage at room temperature.When Aw reached 0.763～0.813,molds and yeasts reproduced quickly causing rapid quality deterioration.(5)The killing rate on molds and yeasts in the Tremella fuciformis samples packaged in PP pouches were over 82%and 71%,respectively,after 800w microwave treatment for 120 seconds.The treated samples could be safely stored at room temperature for at least 180d.Nonetheless,the initial molds and yeasts counts should be controlled at low levels in order to receive the desired results.(6)Vacuum packing could inhibit microbial reproduction,mold growth in particular,as compared to regular packing without vacuumization.(7)The Suspension at the dose of 0.75g/kg which wan made from the Tremella fuciformis product can remarkly put up the weight of the mice organs such as thymus and spleen,and improve the amount of hemolysin.At the dose of 1.5g/kg the suspension had a significant role in improving the charcoal clearance rate,the phagocytosis of peritoneal macrophages and production of hemolysis in mice.