Study On The Quality Control Standards Of Ferment Liquid

Walnut green husk, as a major waste of walnut, contains a lot of active substances, with abundant nutritional value and functional properties. Ferments is a promising practice of walnut green husk development. Currently ferment market is relatively chaos, quality index system has not yet been established. This study chose some commercially available ferment products and the walnut green husk ferment fermented by walnut green husk, fruit as objects to do a comparative analysis about the sensory index, physicochemical index, active ingredients. Moreover, the antioxidant activity and bacteriostatic efficacy of walnut green husk ferment in vitro were studied. The main contents and results were as follows:1. The preparation of walnut green husk ferment and sensory evaluationWalnut green husk ferment was made through the initial fermentation and deep fermentation with no added microbial strain, walnut green husk and complex fruits and vegetables as raw material. At the same time, the sensory indexes were analyzed and compared with the commercially available ferments. The quality of walnut green husk ferment was excellent with a clear and transparent fruit vinegar body, an acid color and luster, a fruit flavor and a sweet and sour taste, which showed good edible characteristics. Comparing with the commercially available ferment products, walnut green husk ferment was slightly better in color, fragrance, flavor and shape.2. Determination of physical and chemical indexes in walnut green husk fermentPhysical and chemical components in walnut green husk ferment and commercially available ferment products were analyzed. The results showed that acidity, protein content and reducing sugars had not diverged much between walnut green husk ferment and commercially available ferment products, but the latter had higher contents of soluble solids and total sugars. Conventional physical and chemical indicators parameters in the edible ferment was initially proposed.3. Analysis of functional indexes in walnut green husk fermentFunctional component spectrums in walnut green husk ferment were more thorough analyzed, including enzyme spectrum, mineral spectrum, polyphenol spectrum, oligosaccharide spectrum, aorganic acid spectrum etc. Meanwhile enzyme spectrum and mineral spectrum in commercially available ferment products were also determined. Walnut green husk ferment and commercially available ferment products were high in SOD and low in lipase, protease and amylase. At the same time, seven kinds of minerals were also found in walnut green husk ferment and commercially available ferment products, wherein the potassium content was the highest and zinc content was the lowest. Through the antioxidants studies found that total polyphenols content was highest in the ferment, followed by total flavonoids and Vc in the commercially available ferment, while Vc content was higher in the walnut green husk frment. Determination of polyphenols by HPLC in the walnut green husk ferment found that the order of polyphenols monomer content was procyanidine> gallic acid> ferulic acid> catechin> chlorogenic acid> rutin> caffeic acid> quercetin. Detection of oligosaccharides by HPLC-ELSD found that the total content of stachyose and raffinose in the walnut green husk ferment were 3134.9 μg/mL, and no cane sugar, fructose and lactose. Moveover,12 kinds of organic acid in walnut green husk ferment were identified by　LC-MS.4. Research on antioxidant activity of walnut green husk fermentThrough the studies found the IC50 values of walnut green husk ferment on DPPH·, O2·-,·OH were 0.46%,1.88% and 4.83% respectively. Moreover, walnut green husk ferment had good reducing power and total antioxidant capacity and dose-dependent, but Fe2+ chelating ability was poor.5. Research on bacteriostatic activity of walnut green husk fermentThrough bacteriostatic test found that walnut green husk ferment had varying degrees of antimicrobial effect to 4 kinds of patho genic bacteria, bacteriostatic circle diameter sizes were followed by s. aureus> salmonella> e. coli> b. subtilis.The MIC values were in the order of e. coli> s. aureus, salmonella> b. subtilis. The results showed that bacteriostatic ring size had certain parallelism with corresponding MIC values, but had no correlation ratio.