Preparation of flaky mashed potatoes

1. Production process

Potato → cleaning → peeling → slices → pre-cooking → cooling → cooking → grinding → dry → crushing → packaging → finished products.

two。 Key points of production

The main results are as follows: (1) the raw materials are selected to remove germinated and green potatoes and rotten and diseased potatoes. If there is sprouting or turning green, the germinated or green part must be cut off or completely removed before it can be used to ensure that the content of solanine glycosides in potato products does not exceed 0.02%, otherwise it will endanger personal safety.

(2) wash the potatoes into the pool and stir to wash the sediment and surface dirt. If the flow operation generally pour the raw materials into the feed port, pick up rotten potatoes, stones and sand on the conveyor belt, clean them up and send them into the washing machine through the flow trough or lifting bucket. Cleaning is usually scrubbed in a drum washer and can be operated continuously.

(3) the methods of peeling include manual peeling, mechanical peeling, steam peeling and chemical peeling. Peeling by hand, usually with a stainless steel knife, its efficiency is very low. Mechanical peeling, is the use of coated steel sand, rough surface of the drum or roller, by friction force to wipe off the skin, the commonly used equipment is the skin eraser, which can be produced in batches or continuously. Lye peeling is to put the potato in a strong alkali solution of a certain concentration and temperature for a certain time, soften and relax the potato skin and bud eyes, and then spray cooling and peeling with high-pressure cold water. The suitable lye mass fraction for lye peeling is 15%-30%, and the temperature is above 70 ℃. Steam peeling, is to treat the potato in steam for a short time, so that the potato skin blisters, and then rinse off the skin with running water. Steam peeling can act evenly on the whole potato surface, about removing the thick skin of 5mm.

The ideal method is to use steam peeling and lye peeling alternately. Because the longer the interval between the harvest and processing of potatoes, the more difficult it is to peel and the greater the loss. In the early processing season, the loss of peeling with steam or low temperature lye is small. In the late processing season, when peeling is more difficult, in addition to alkali treatment, but also after a short period of high-pressure steam treatment, and then rapid pressure relief, and finally rinse with cold water to remove the skin, which will make peeling more effective.

(4) potatoes are generally sliced into 1.5mm thick slices so that they can be heat-treated more evenly during pre-cooking and cooling.

(5) pre-cooking can not only destroy the enzymes in potatoes and prevent tubers from browning, but also get non-sticky mashed potatoes. Potato chips are generally heated to 20min in water of 71 ℃ ~ 74 ℃. The precooked starch must be gelatinized thoroughly. In this way, the starch will age and regenerate during the cooling period, reducing the stickiness of potato chips after rehydration.

(6) wash the boiled potato with cold water and remove the free starch to avoid sticky or scorched phenomenon during dehydration, so that the viscosity of the prepared potato mud can be reduced to an appropriate degree.

(7) the pre-boiled and cooled potato chips were boiled with steam to 30min under atmospheric pressure to make them fully differentiated.

(8) ground potatoes are ground immediately after cooking so that they can be quickly mixed with additives and avoid cell rupture. The machinery used is generally a spiral grinder or a disk crusher with round holes.

(9) Additives are injected into mashed potatoes before drying in order to improve their structure and prolong their shelf life. There are two kinds of additives commonly used, one is a dilute solution of sodium bisulfite, which can be used as a source of sulfur dioxide to prevent non-enzymatic browning of potatoes, and the amount of sulfur dioxide is usually 0.2% 0.4%. The other is to spray glycerol onto the dried potato chips, usually cool the potatoes to (65 ±5) ℃ before adding and store at this temperature. In addition, the addition of antioxidants can prolong the storage life of mashed potatoes. Adding tert-butyl p-hydroxyanisole and 2.6-di-tert-butyl p-cresol to mashed potatoes before drying can prolong the shelf life by 6 months. Steam distillation of antioxidants occurs during drying, so antioxidants will lose about 75%. In addition, the addition of an acid sodium pyrophosphate can react with iron and inhibit the discoloration caused by recooking, which is 0.1% of the quality of the potato.

If fortified potato chips are made, vitamin C75 mg, vitamin B2, 3mg, niacin 20mg and vitamin A 1200IU can be added to each serving of potato chips (85g).

(10) dried mashed potatoes can be dried in a single drum dryer or in a single drum dryer equipped with 4 ~ 6 rollers. After drying, the maximum density of dried potato chips can be obtained, and the water content of the dried potato chips is less than 8%.

(11) the crushed and dried potato chips can be crushed into scales by a hammer grinder, which is a product with suitable structure and packing density.

Production shows that most potato chip processing plants use potatoes with a dry matter content of 20% as raw materials, and 1 ton of finished products need 6.6t~7.0t potato raw materials. For the potatoes most suitable for processing, the peeling loss is about 7%, the slicing loss is about 1.5%, the pre-cooking loss is about 3%, the cooling loss is about 1.5%, the cooking loss is about 1%, and the loss from the drum during drying is about 3% and 5%.

3. Quality Control

The main results are as follows: (1) there are many factors affecting the structure of mashed potato, such as the number of broken cells, the number of gel starch, the absorption of cytoplasm and so on. These factors must be effectively controlled in the production process to ensure a good product structure.

(2) the addition of acid phosphate to the product color can control the gray produced by cooking, so it is no longer a problem to control the color change of potato chips during cooking.

(3) the content of Escherichia coli is not more than 10 / g, there is no Staphylococcus aureus, and the number of mold is not more than 10 / g.

(4) the moisture content of the dried product is less than 8%, which is generally 5%-6%.

(5) the content of reducing sugar and total sugar should be limited to 2% and 3% according to dry weight.