Detailed Explanation of Processing Technology for Small White Pear Acetic Acid Fermented Beverage

(I) Product Features

It combines the health benefits of both pear and acetic acid fermented beverages, and is rich in nutrients. Traditional Chinese medicine holds that: pears are cold in nature and sweet in taste, with effects such as moistening the lungs, reducing phlegm, relieving cough, reducing internal heat, and calming the mind. The acetic acid produced by acetic acid fermentation has effects such as eliminating fatigue, refreshing the spirit, promoting salivation and quenching thirst, and increasing appetite.

(II) Main Raw and Auxiliary Materials

Small white pear, pectinase, wine yeast 1450#, acetic acid bacteria AS1.41, aspartame (APM), xanthan gum, white granulated sugar, honey.

(III) Main Equipment

Belt juice press, fruit crusher, constant-temperature incubator, shaker, seed tank, saccharification tank, plate-and-frame filter, air compressor, refrigerator, and alcohol fermentation and lactic acid fermentation reactors.

(IV) Process Flow

Small white pear → washing → crushing, juicing → pectinase treatment → filtration, removal of residue → adjusting sugar concentration → ethanol fermentation → acetic acid fermentation → pear vinegar → blending → fine filtration → homogenization → bottling → sterilization → cooling → finished product

(V) Explanation of Key Operation Points

(1) Yeast preparation: slant medium, 10°Bx wort plus 2% agar, inoculate with yeast, culture at 28-30°C for 24 hours.

Flask medium (first-level seed): place 150 milliliters of 10°Bx wort in a 250-milliliter flask, inoculate with 5% activated stock culture, shake well, and culture at 28-30°C for 24 hours.

Large flask culture (second-level seed): take 400 milliliters of 10°Bx wort and place it in a 5000-milliliter flask, add 10% bran hydrolyzate, inoculate with 400 milliliters of first-level seed, and culture at 28-30°C for 18 hours.

Liquid wine yeast (third-level seed): take 140 kilograms of pear juice, add it to a 200-liter seed tank, add 10% bran hydrolyzate, adjust the sugar degree to 10°Bx, inoculate with 10% second-level seed, and culture at 28-30°C for 10 hours.

(2) Preparation of acetic acid bacteria seed

Slant culture: 10 grams of glucose, 1 gram of yeast extract, 2 grams of calcium carbonate, 3.5 milliliters of anhydrous ethanol, 2 grams of agar, add 100 milliliters of distilled water, adjust pH to 6.5, inoculate with acetic acid bacteria, and culture with shaking at 30-32°C for 48 hours.

Flask culture: take 100 milliliters of the above liquid medium (without agar) and place it in a 500-milliliter flask, add 3.5 milliliters of anhydrous ethanol, then inoculate with the above activated acetic acid bacteria culture, with an inoculation amount of 10%, and culture with shaking at 30-32°C for 36 hours.

Large flask culture: take 4000 milliliters of pear juice and place it in a 5000-milliliter large flask, inoculate with 10% acetic acid bacteria culture liquid from the flask, and culture with shaking at 30-32°C for 20 hours.

(3) Preservation method of acetic acid bacteria: use the liquid seed preservation method. After the small flask is inoculated and cultured, when the acidity reaches 1.8-2.2 grams/100 milliliters, add about 2% calcium carbonate and preserve at low temperature in a refrigerator.

(4) Pectinase treatment of pear juice: add 0.12% pectinase to the pear juice and keep it at 50-55°C for 2 hours.

(5) Adjusting the sugar degree of pear juice: the sugar degree reaches 10%, reducing sugar >4%, and the acidity (calculated as acetic acid) reaches about 0.2%.

(6) Ethanol fermentation: carried out in a sealed tank, with the temperature maintained at 28-30°C, a filling amount of 80%, and a fermentation time of about 5 days. The ethanol content of the mature fermentation liquid is 5%, the acidity (calculated as acetic acid) is about 0.6%, and the residual sugar is controlled at 0.5%-0.8%.

(7) Acetic acid fermentation: use liquid submerged fermentation, inoculate with 10% acetic acid bacteria culture liquid, stir and aerate continuously, with an aeration amount of fermentation liquid:air volume = 1:0.06-0.08, controlled in three stages.

Early stage: the tank temperature is controlled at 32-34°C, the air volume should be small, and the time is about 24 hours.

Middle stage: increase the air supply, with a temperature of 34-35°C and a time of about 16 hours.

Late stage: 33°C, about 20 hours, and it is preferable to stop when the measured acidity in the fermentation liquid no longer rises.

(8) Blending: add 0.03% APM, 0.2% xanthan gum, honey, and white granulated sugar for blending.

(9) Homogenization: heat the material liquid to 50°C for homogenization, with a first-stage homogenization pressure of 18 megapascals and a second-stage homogenization pressure of 25 megapascals.

(10) Sterilization: after the material liquid is filled, sterilize at 85°C for 15-20 minutes.

(VI) Product Quality Indicators

Total sugar (calculated as glucose) 6%-8%; total acid (calculated as acetic acid) 0.3%-0.5%; soluble solids 8%-10%.