Detailed Explanation of Wort Fermented Beverage Processing Technology

Barley (Hordeum vulgare L.), also known as naked barley, rice barley, bare barley, etc., is a grass family plant. It ranks fourth in world grain crop production, after only @#@245@#@, rice and corn. Its uses are quite extensive, with wide applications in food, feed, brewing, medicine, textiles, the nuclear industry, weaving crafts and other fields. Germination treatment can improve the nutritional value of cereal seeds, increase the digestibility and absorption rate of protein and starch, increase the content of limiting amino acids and vitamins, and can also reduce toxic, harmful and certain anti-nutritional components. At present, the lactic acid fermented beverage popular on the Chinese market is traditional yogurt. In recent years, there have also been research reports on producing lactic acid fermented beverages from vegetable juice, but due to the strong seasonality of raw materials, no products have yet been put on the market. This article introduces a beverage produced by lactic acid fermentation using low-priced, abundantly available barley as the main raw material. It not only adds a new variety of beverage, but also opens up development prospects for the application of biotechnology in the deep processing of agricultural products, and opens a new path for the transformation and value-added utilization of grain.

I. Process Flow

Barley → steeping → germination → drying → grinding → saccharification → wort → adding auxiliary materials and blending → homogenization → sterilization → inoculation → aseptic filling → fermentation → post-ripening → inspection → finished product.

II. Key Operation Points

1. Preparation of malt wort. A double decoction saccharification process is used, with a water ratio of 1:6 (W/W). First, protein rest is carried out at 50°C--52°C for 1 hour, then one third of the mash is taken for the first boiling, boiled for 3--5 minutes, and then mixed with the remaining two thirds of the mash. The temperature is adjusted to 63°C--65°C, and saccharification is carried out with heat preservation until the iodine solution no longer changes color, that is, saccharification is complete. The saccharification time depends on the quality of the malt. The fully saccharified mash is separated into liquid and thick phase. The latter is heated to 72°C--73°C, held for 10 minutes and then boiled, and then mixed with the liquid portion so that the material liquid temperature is maintained at 75°C--78°C for 5 minutes, filtered hot at 78°C, thus obtaining original wort. This wort is boiled and kept boiling for a certain period of time in order to control the boiling intensity required by the process and remove coagulable beta-globulin, etc.

2. Adding auxiliary materials and blending. The wort obtained by saccharifying 10 kg of barley is diluted to 100 kg with sterile water, and 10% fresh milk is added (milk powder may also be used; milk powder mixed with 7 times its amount of water gives milk liquid), 5% lactose, 5% white granulated sugar (the sugar liquid is dissolved and filtered in advance), and 0.5% agar (already dissolved). Stir evenly.

3. Homogenization. A high-pressure homogenizer is used, with homogenization pressure above 18 MPa. Or a colloid mill is used for homogenization for 5 minutes.

4. Sterilization. Heat at 95°C--100°C for 2 minutes for sterilization; if conditions permit, a plate heat exchanger may be used. Then cool rapidly to 40°C.

5. Treatment and preparation of the starter.

The starters used in this experiment are Lactobacillus bulgaricus and Streptococcus thermophilus.

(1) Preparation of skim milk medium. Place 20 g of skim milk respectively into sterilized dry 250 ml Erlenmeyer flasks and 18x180 mm test tubes, and sterilize in an autoclave at 0.1 MPa and 121°C for 15 minutes. When dissolving, the weight ratio is skim milk powder: original wort = 1:8. Stir thoroughly, cool to 41°C, and carry out inoculation and culture.

(2) Activation and culture of strains. Use autoclaved skim milk-original wort as the culture medium for seed culture and scale-up culture. The seed medium is held at an autoclaving temperature of 110°C for 30 minutes, then rapidly cooled to 42°C. For the scale-up medium, it needs to be kept at 95°C for 30 minutes for sterilization, rapidly cooled to 40°C, and then inoculated into clean Erlenmeyer flasks and test tubes containing sterilized milk, with the ratio of inoculated and cultured Lactobacillus bulgaricus to Streptococcus thermophilus maintained at 1:1, and sealed with sterilized clean cotton plugs. Then place in a constant-temperature incubator at 42°C for activation culture. The culture time is about 10--12 hours, until coagulation. After taking out, place at 5°C for about 24 hours so that flavor substances are improved, and then carry out the second and third activation, so that the strains can meet the requirements of this experiment.

6. Inoculation. Inoculate the above domesticated Lactobacillus bulgaricus and Streptococcus thermophilus into the mixed material at a ratio of 2%--3%, and stir and homogenize.

7. Aseptic filling, fermentation, post-ripening. Under aseptic conditions, fill into sterilized bottles and seal, and send to a heat preservation room for fermentation culture. The fermentation temperature is about 40°C, and the time is 4--6 hours. When the culture reaches a certain acidity, it can be sent to a cold storage for low-temperature post-ripening. Post-ripening conditions: temperature 0°C--4°C, time 10--12 hours, pH value 4.1--4.2.

8. Inspection of finished product. Inspect according to the product's sensory indicators, physicochemical indicators and microbiological indicators. After passing inspection, it can be packaged and shipped out of the factory.

III. Product Quality Indicators

1. Sensory indicators. Color: uniform and consistent, slightly pale yellow.

Taste and odor: moderately sweet and sour, with an obvious fresh barley aroma and the unique delicate fragrance of lactic acid bacteria fermented beverages, a pure lactic acid taste, and no off-flavors or foreign tastes.

Texture: delicate mouthfeel, presented as an emulsion, uniform and consistent without stratification, with a small amount of sediment allowed.

2. Physicochemical indicators. Soluble solids >=10.0%; protein >=3.2%; fat >=1.0%; acidity (calculated as lactic acid) 0.63%--0.95%. Lead (calculated as Pb) <=0.5 mg/kg; arsenic (calculated as As) <=0.5 mg/kg; copper (calculated as Cu) <=1 mg/kg.

3. Microbiological indicators

Total bacterial count <=100 cfu/ml; coliform bacteria <=3 cfu/ml; pathogenic bacteria must not be detected.