Processing Methods and Technical Key Points for Fresh Peach Nectar
Pulpy juice is also called puree-style juice, with the commercial name "nectar". Fresh peach nectar is one of the most popular juice drinks on the market today. Its process flow is:
1. Raw material selection: Select fully ripe, fresh peaches with good flavor, abundant juice and free from pests and diseases. Peaches that are not fully ripe need to undergo after-ripening.
2. Raw material pretreatment
1) Cleaning. After the raw materials are selected, wash and scrub them with clean water to remove the fuzz. After cleaning, rinse them in a 1% hydrochloric acid solution or detergent solution to remove pesticide residues, then rinse again in clean water and drain.
2) Halving and pitting. Use a halving and pitting machine.
3) Soaking for color protection. Place the halved and pitted raw materials into a mixed solution of 0.1% iso-ascorbic acid and citric acid to soak for color protection.
3. Heating and pulping: Heat the fruit pieces at 90-95°C for 3-5 minutes to promote softening, then pass them through a pulper with a hole diameter of 0.5 mm to remove the peel.
4. Flavor adjustment: The pulp obtained after the above steps needs to be adjusted to increase flavor. During adjustment, add ingredients such as granulated sugar, citric acid and L-ascorbic acid. The proportions are 100 kg peach pulp, 80 kg 27% sugar solution, 0.45 kg citric acid, and 0.07-0.2 kg L-ascorbic acid.
5. Homogenization and deaeration: Homogenization is intended to break the pulp particles suspended in the juice into smaller particles so that they are evenly dispersed in the juice, increase the stability of the juice, and prevent separation.
The homogenization method is to pass the coarsely filtered juice through a high-pressure homogenizer, so that the pulp particles and colloidal substances in the juice pass under high pressure through small holes with a diameter of 0.002-0.003 mm and become finer particles. In production, a homogenizer of 130-160 kg/cm2 is generally used.
In addition, a colloid mill can also be used for homogenization. When the juice flows through the narrow gap of the colloid mill with a clearance of 0.05-0.075 mm, the pulp particles in the juice impact and rub against each other due to the strong centrifugal force, thereby achieving the purpose of homogenization.
During juicing, gases such as oxygen, nitrogen and carbon dioxide enter the fruit. Among them, nitrogen can cause oxidation of substances such as vitamin C and pigments, and corrosion of tinplate cans. Therefore, deaeration must be carried out. There are mainly the following two deaeration methods:
1) Vacuum method. Put the juice into a vacuum container and make the juice spray out in a fine mist to deaerate. The vacuum degree used in the vacuum method is 685-711 mmHg or above, and the temperature is lower than 43°C.
2) Nitrogen exchange method. The juice flows in from the top of an upright glass cylinder or stainless steel cylinder, and nitrogen is pressed in from the bottom of the cylinder. After nitrogen is added, countless small bubbles form in the juice, replacing the oxygen in the juice and thereby achieving the purpose of deaeration.
6. Sterilization and canning: Heat the juice to 95°C, maintain for 1 minute, and immediately fill into cans while hot.
7. Sealing and cooling: Tighten the bottle cap and invert the can for one minute. After sealing, quickly cool in stages to about 38°C, then store in the warehouse.
Qualified nectar finished product is pink or yellowish brown, with a slight dark red tint; the liquid is uniformly turbid, and fine particle sediment appears after long standing; it has peach juice flavor and no off-flavor; soluble solids reach 10%-14%.