Detailed Explanation of the Processing Methods and Technical Points of Candied Sweet Potato

1. Raw and auxiliary materials: fresh sweet potatoes, white granulated sugar, maltose, citric acid, sodium sulfite, edible gelatin, quicklime, etc.

2. Process flow: sweet potatoes -- cleaning -- peeling -- cutting -- color protection -- hardening -- blanching -- gelatin dipping -- sugar boiling -- sugar soaking -- drying -- packaging -- finished product

3. Key points of process operation:

① Cleaning: select fresh potatoes that are firm in texture, free from wounds, pollution, and rot, and round in shape, and wash off the soil with a machine or by hand.

② Peeling: remove the potato skin with a peeling machine or by hand. Remove about 1 mm thick, keeping the potato core.

③ Cutting: cut into rectangular, diamond, and other various shapes according to product requirements, so that the product appearance is beautiful and elegant. After cutting, wash off the scraps and starch attached to the surface of the potato pieces with clean water.

④ Color protection: put the cut potato pieces into a 0.3%-0.5% sodium sulfite solution, soak for 90-100 minutes, then take them out and rinse with clean water for 5-10 minutes.

⑤ Hardening: put the color-protected potato pieces into a 0.2%-0.5% fresh lime liquid and soak the potato pieces for 12-16 hours, then take them out after they are completely hardened, and rinse with clean water for 10-15 minutes.

⑥ Blanching: put the hardened potato pieces into boiling water and boil for several minutes, then remove and drain off the remaining water.

⑦ Gelatin dipping: put the blanched potato pieces into a prepared 0.3%-0.5% gelatin solution, and dip the gelatin under reduced pressure, with a vacuum degree of 650-680 mmHg, for 30-50 minutes, and the gelatin liquid temperature at about 50°C.

⑧ Sugar boiling and sugar soaking: put 20 kg of white granulated sugar and 30 kg of water into a stainless steel pot to make a sugar liquid, take out 7.5 kg of sugar liquid and set aside for later use, add 1.5 kg of maltose to the remaining sugar solution, stir, and then boil the solution, pour in 50 kg of pre-weighed sweet potato pieces and boil for 5 minutes, immediately add 1.5 kg of the cold sugar liquid previously set aside, boil the sugar liquid again for 5 minutes and add 1.5 kg of cold sugar liquid. After repeating this three times, when the sugar liquid boils again, add 1.5 kg of granulated sugar and 1 kg of cold sugar liquid simultaneously in three portions, after the fourth boiling add 7.5 kg of granulated sugar, after boiling again add 3 kg of granulated sugar, and switch to low heat and continue heating and boiling until the potato pieces become translucent, then add 75 g of citric acid, stir evenly, and remove the potato pieces to drain off the sugar liquid. The candied sweet potato made by this method is crystal clear and translucent, with excellent flavor and color. Alternatively, put the prepared potato pieces into a pot, add 75 kg of water, 20 kg of white granulated sugar, 1.5 kg of maltose, and 100 g of citric acid, heat the pot to boiling as quickly as possible over high heat, and boil for about half an hour, with the potato pieces preferably cooked but not mushy. Because sweet potato varieties differ, the sugar boiling time also differs. Take the potato pieces and sugar liquid out of the pot together and put them into a large vat to soak for 24 hours, so that the potato pieces further absorb sugar. Then remove the soaked potato pieces, spread them in a single layer flat on a steaming rack or bamboo mat, and drain off the sugar liquid.

⑨ Drying: after draining off the sugar liquid, they can be sent into a drying room for baking, maintaining the temperature at 60-70°C. Pay attention to adjusting the position and turning frequently, and carry out moisture removal treatment every 2-3 hours to shorten the drying time. Generally, bake continuously for about 12 hours, so that the moisture content of the potato pieces drops to 16%-18%, and take them out of the room when they do not stick to the hand when touched and are slightly elastic. The potato pieces can also be placed under strong sunlight to dry, and the potato pieces should be turned from time to time.

⑩ Shaping and packaging: remove scraps and misshapen small pieces from the potato pieces that have come out of the drying room or passed the sun-drying check, and pack them into food bags by a certain weight for storage or sale. If multicolored candied sweet potato is to be produced, the potato pieces can be divided into several portions before being boiled in the sugar liquid, and during sugar boiling, various natural food colorings in prescribed amounts can be placed separately into the pot to make multicolored candied sweet potato with an attractive color.