A Study On Fruit Vinegar Made Of P. Pyrifolia And Flavor

Sand pear [Pyrus pyrifolia] was originally cultivated in China Yangtze valley and south of the area. In the 1980s, some new cultivars were bred one after another in Japan and South Korea based on the native native sand pear cultivars and have been introduced into our country in recent years. As a type of the nutritional fruits, the sand pear industry has the broad prospects for development. And research of fruit quality and products processing can play the remarkable promoting role to the pear industry development.Cultivars, i.e. Suisho, Hosui, Xuli, and Atago, were selected for determining of the physical characteristics and the basic nutrient content. The result showed that:fruit shape index,0.825-0.942; simple fruit weight,324.9-189.5 g; total acid,0.71%-1.23%; total sugar,7.06%-8.53%; reductant sugar,6.43%-7.26%; tannin,0.71%-3.95%; pectin,0.46 %-2.00%; Vitamin C content,1.7-6.8 mg/100g. The highest level of the main macro-elements among four cultivars was 245.6 mg/100g of K (Hosui),3.78 mg/100g of Ca (Hosui) and 24.73 mg/100g of Mg (Atago), respectively. While,2.47 mg/100g of Fe (Atago),21.34 mg/100g of Zn (Suisho),1.06 mg/100g of Mn (Suisho) was the highest level for relative trace element in above cultivars.The pear vinegar of Suisho was brewed using the solid fermentation. The fermentation condition parameters were optimized by Response Surface Methodology (RSM). The optimum conditions for brewing were:9.6% of inoculation quantity of acetic acid bacteria,11.5% of the initial sugar,120 h of ethyl alcohol fermentation,7.2% of the initial concentration of ethanol,144 h of the acetic fermentation and pH,3.2.Solid Phase Micro-extraction (SPME) for volatile sampling was optimized using RSM. Extraction conditions that gave good total recovery and diversity of compounds from pear slurry headspace were found to be:PDMS/DVB fiber,3.4 g oil sample in 15 mL vessel; exposure for 45 min at 46℃; 11% of salt. The aroma of Suisho and the vinegar were studied by HS-SPME coupled with GC/MS.32 volatile compounds in Suisho fruit and 15 volatile compounds in vinegar, such as ethyl acetate, propanoic acid ethyl ester, butanoic acid butyl ester, butanal, phenol 2-methyl-5-(1-methylthyl), cyclohexene, butanol, 3-cyclohecen-l-ol,4-methyl-1-(1-methylethyl), benzolioxole 5-(2-propenyl), propanoic acid 2-methyl-ethyl ester, hexenoic acid ethyl ester, benzenepropanol and so on were identified and quantitatively analysed using internal standard.4.8% of titrated acidity,3.2 mg/100mL of Vitamin C,5.28 mg/100mL of Ca,25.58 mg/100mL of Mg,0.13mg/100mL of Cu,7.59 mg/100mL of Fe,18.07 mg/100mL of Zn were found in pear vinegar. The hygienic indice of pear vinegar meet with the relative standard of GB2719-2003. The result of sensory attributes of pear vinegar assessed by Fuzzy was "accepted generally".