Processing Technology of clarified Pear Juice

(1) technological process

Fresh fruits such as → wash and drain → finishing → broken → color protection → press → coarse filtration → clarification → juice fine filtration → composition adjustment → bottling → exhaust → sealed → sterilization → cooling → product

(2) description of operation points

(1) cleaning and sorting of pears: the soil and pesticide residues carried on the peel are removed by cleaning, so that the microbial biomass is reduced to 2.5%-5.0% of the original. Cleaning methods include rinsing, brushing, spraying and so on, and several methods are often used together. The main purpose of sorting is to remove rotten, mechanically damaged fruit and remove impurities. Manual selection is often used.

(2) crushing and color protection: because the pear skin is thick, the meat is hard, and the stone cell content is high, so the crushing process is an important process to improve the juice yield, and the size of the broken fruit should be suitable, generally 3-4 mm. In order to prevent oxidative browning of fruits in contact with air, color protection measures should be taken in the crushing process, generally adding 0.8% citric acid or 0.08% vitamin C, or heavy potassium sulfite (100 mg / kg). The crushing equipment includes hammer crusher, tooth plate crusher and centrifugal crusher.

(3) Juice extraction: juice extraction is an important part of juice production process, which generally requires high juice yield, good juice color and less nutrient loss. Due to the high pectin content in the fruit, the juice yield is low when the juice is directly extracted after crushing, and the juice is turbid. 0.2% Pectinase can be added to decompose the pectin. The enzymatic hydrolysis temperature is 35-45 ℃ and treated for 2 hours. At present, the commonly used juicers are wrapped juicer, horizontal cylinder juicer, spiral juicer and belt juicer.

(4) clarification: clarification is the most critical process of juice-making process. After rough filtration, there are often some suspended solids and colloidal particles, the main components are cellulose, protein, enzyme, sugar, pectin and other substances, which seriously affect the transparency and stability of fruit juice. The methods are as follows: ① diatomite clarification method: the dosage does not exceed 420g / 1000 liter; ② gelatin-tannin method: the optimum dosage of 0.5% gelatin solution and 1% tannin solution is 7.5% and 7% respectively.

(5) Filtration: the clarified pear juice also needs to remove precipitates and unstable suspended particles. The filtration effect of diatomite filter is the best, the dosage of diatomite is about 0.01%, and the filtration pressure of 0.3 ~ 0.35 MPA is adopted. Plate and frame filter is also one of the commonly used equipment, and ultrafiltration equipment can also be used.

(6) Sterilization: pasteurization and high temperature instantaneous sterilization can be used. Instant sterilization: about 93 ℃, 15: 30 seconds, commonly used equipment are tubular heat exchanger, plate heat exchanger. Filtration has the effect of cold sterilization.

(7) filling: hot filling, cold filling and aseptic filling can be used.