Detailed Explanation of the Processing Technology and Production Method of Chestnut Fruit Tea

(I) Overview

The chestnut is a famous and high-quality dried fruit in China, rich in nutrients. The chestnut kernel has a high content of amylopectin, with a fine, powdery texture. Eaten raw or cooked, it is sweet, glutinous, fragrant and crisp, with an excellent flavor, and is deeply loved by people. The chestnut also has considerable medicinal and health-promoting effects. According to the ancient text "Dian Nan Ben Cao" (Materia Medica of Yunnan), the chestnut is sweet and warm in nature and flavor, and has the effects of benefiting qi, strengthening the stomach and intestines, tonifying the kidney, strengthening the tendons, and invigorating blood circulation.

(II) Raw Materials and Formula

Chestnut: 15%:

Carrot: 3%;

Granulated sugar: 4%;

Milk powder: 2.5%;

Ethyl maltol: 0.02%;

Xanthan gum: 0.35%;

Drinking water: balance.

(III) Process Flow

Chestnut → shelling → removing the inner skin → color protection → pre-cooking → pulping (cooked carrot slices, mixed syrup) → grinding → blending → homogenization → degassing → filling → sterilization → inspection and factory release

(IV) Key Operating Points

① Shelling, removing the inner skin, and color protection: Use a shelling machine or manual shelling. Before shelling, the chestnuts should first be sun-dried for 6-10 hours, or roasted on a high-temperature chain-belt roaster at 150-180°C for 20-25 seconds, so that the chestnut shells develop cracks. The machinery that comes into direct contact with the chestnut kernels during the shelling process should be made of stainless steel material to prevent browning caused by this; using the alkaline solution corrosion and polishing method, put the shelled chestnut kernels into a sodium hydroxide solution with a concentration of 6%-8% and a temperature of 90-95°C (weight ratio of chestnut kernels to alkaline solution is 1:2) and corrode for 2-3 minutes, while simultaneously passivating the enzyme activity in the surface layer of the fruit. After corrosion, quickly remove them and wash off the alkaline solution, then transfer to a drum-type polishing machine to remove the inner skin; after polishing off the inner skin, rinse with tap water, then neutralize with a 2%-4% dilute hydrochloric acid solution for 4-6 minutes. After removing and washing clean, put them into the color-protecting solution for later use (composition of the color-protecting solution: 0.1% citric acid, 0.1% sodium chloride, 0.05% disodium edetate).

② Pre-cooking: Remove the chestnut kernels from the color-protecting solution and put them into a boiling pre-cooking solution and boil for 40 minutes (weight ratio of pre-cooking solution to chestnut kernels is 3:2; composition of the cooking solution: 15% sucrose, 0.05% sodium chloride, 0.12% disodium edetate, 0.1% citric acid).

③ Preparing cooked carrot slices: Remove the fibrous roots, diseased spots, etc. from the carrots, wash them clean, and cut them into thin slices of about 3 mm. Steam-cook in a pressure cooker at 110°C for 20 minutes, then cool for later use.

④ Preparing the mixed syrup: Weigh out sucrose, maltose, and liquid glucose according to the input amount and formula. First, heat and dissolve 100 kg of sucrose with 50 kg of water, then add maltose and liquid glucose. Heat to boiling and maintain at above 80°C for 10 minutes.

⑤ Pulping and grinding: Mix the cooked chestnut kernels, carrot slices, and mixed syrup, and pulp them with a pulping machine with a sieve pore diameter of 0.2 mm; after pulping, further refine the slurry with a colloid mill, then transfer to a stirring tank for later use.

⑥ Blending: Weigh out auxiliary materials such as milk powder, ethyl maltol, and xanthan gum according to the formula, mix them thoroughly, and then transfer to the stirring tank. Turn on the stirrer and mix the various raw and auxiliary materials in the tank evenly.

⑦ Homogenization: Homogenize with a high-pressure homogenizer at a pressure of 18-22 MPa. Under high pressure, the material generates cavitation effects, shear effects, and collision effects, with a fineness below 1-2 microns.

⑧ Degassing, filling, and sterilization: To prevent oxidation and browning of the finished product, perform vacuum degassing before filling. The conditions are: temperature 35-45°C, vacuum degree 90.6-96.0 kPa, time 10 minutes; use automatic filling. Seal promptly after filling. Can specification 250 mL; the vacuum degree during the sealing process is 0.03-0.035 MPa; sterilization formula 10'-30'-10'/100°C. After sterilization, rapidly cool to 40°C, wipe the cans, then hold at 25°C for 7 days.

⑨ Inspection and factory release: After the holding period, conduct sampling inspection according to the standard-specified inspection procedures and methods. After passing inspection, package and release from the factory.

(V) Quality Standards

1. Sensory Indicators

Color: light yellow to orange-yellow;

Tissue form: a uniform turbid liquid, with a thick mouthfeel, no impurities, and no precipitation or layering after long standing;

Taste and aroma: has the chestnut aroma that chestnut fruit tea should have, with a relatively obvious carrot flavor, moderate sweetness, and no off-flavors.

2. Physicochemical Indicators

Net volume: 250 mL, allowable tolerance ±3%, but the average of each batch must not be lower than the specified volume;

Soluble solids (by refractometer): 18%-22%;

Insoluble solids: 78%.