Selection of raw materials

Because processed fruit preserves and preserves are mainly made by soaking the fruit with sugar liquid, so that the sugar in the sugar can penetrate into the fruit to replace the water in the fruit. Therefore, the quality of fruit varieties must be strictly selected in order to produce high-quality varieties. The raw materials for making preserved fruits require that the pulp be dense, resistant to cooking, not overripe when mature, and the pulp maintains a certain hardness, but different varieties have different requirements. For example, fresh apricots for making preserved apricots are required to be golden in color, delicate in texture, tough, neither soft nor spongy when mature, easy to separate from the core, and resistant to storage. Beijing's "Tiebada" and "Shanhuangxing" are ideal raw materials. However, "water-born" and "cotton-born" apricot varieties that contain a lot of water and easily become soft and cottony cannot be used. For fresh peaches to make peach preserves, it is required to choose white-fleshed varieties. Other requirements are the same as fresh apricots. For example, Beijing's "Kuaihong Peach" and "Dabaiye" are both suitable. Making apple preserves requires fresh apples with low water content, loose fleshy tissue, easy absorption of sugar liquid during cooking, and difficulty in boiling. The flesh is plump and plump, and the shape is round. In the past, "Huailai apples" were mostly used, but now the varieties have been expanded, and "Guoguang", "Japanese Jin", "Hongyu", etc. can be used to process preserved fruits. Processing of candied dates requires fresh dates to have large bodies and small cores, thin skin, thick flesh, loose pulp, low water content, high sugar content, easy absorption of sugar liquid, and the finished product is generally fat, plump and translucent. In the past, the "big sugar dates" produced in Pinggu and Shunyi counties were the most ideal, and the "foil dates" (also called soaked dates) produced in Changping and Fangshan counties were also suitable. There are two types of candied hawthorns that are often used: one is the red fruit with a large fruit shape, or called Shanlihong, and the other is the hawthorn with a smaller fruit shape. The processed product of the former is called candied red fruit, and the processed product of the latter is called candied quince.

Pretreatment

The key to forming the unique flavor of preserved fruits lies in meticulous workmanship. A series of pre-treatments are carried out after selecting the fresh fruits for making preserved fruit, which is the material basis and prerequisite for the quality of the product. For example, fresh apricots that are processed into preserved apricots need to be pitted. The method of digging out the core is to use a knife to cut into the fruit flesh along the seam, as deep as the core, twist the fruit with both hands to make half of the fruit and core fall off, and then use a knife to dig out the core on the other half. The fruit after digging out the core is called "bowl", which is then washed and smoked with sulfur. If you are making green plums from green apricots, first soak them in 15% salt solution for 3 days to separate the core from the pulp, then press it open with a plate to form a "bowl", rinse it and set aside. For the pre-selection treatment of fresh peaches, first boil them in 4-6% NaOH solution for 10 seconds, remove them and rinse them in clean water while stirring them so that they rub against each other to make the peels fall off. If it is a stick-core product, dig it out. The core and core-free varieties are processed in the same way as fresh apricots, making them into "bowls" and then smoked with sulfur; the fresh dates for making candied dates do not need to be peeled, but they must be peeled so that the sugar liquid can fully penetrate into the fruit. There are two methods of peeling: manual and mechanical. Peeling is to cut many fine lines along the length of the fruit. After the candied dates are made, many filamentous stripes are formed, so they are called "golden candied dates". Making preserved apples and pears requires two processes: peeling and core removal. Peeling can also be divided into manual and mechanical peeling. After peeling, use a knife to scoop out the heart and core to form a "bowl" and wash it. Sulfur fumigation. Fresh red fruits should be pre-selected to remove seeds and washed before use. No sulfur fumigation is required.

Sulfur fumigation

The method of sulfur fumigation is generally to place the pre-processed raw materials on a drawer and put them together with the sulfur in the iron bowl into a large vat or cement pool. The sulfur is ignited and covered with a quilt or sack for sulfur fumigation. The sulfur fumigation can also be carried out in a specially set up sulfur fumigation room. The amount of sulfur used is generally 0.2 to 0.3% of the raw material, and the sulfur fumigation time depends on the size and nature of the fruit, generally 30 to 60 minutes. You can also soak in sodium bisulfite solution with a concentration of 0.5 to 0.6% instead of sulfur fumigation. Sulfur fumigation or sodium bisulfite soaking can prevent the tannins in the fruit from being oxidized, thereby maintaining the bright yellow or golden color and maintaining vitamin C. At the same time, sulfur dioxide dissolved in the sugar solution can also prevent the fermentation of the sugar solution.

Candied fruit

The processing principle of candied fruit is based on the preservation of high-concentration sugar liquid. During the sugar cooking process, a large amount of sugar is infiltrated into the pulp and the water is discharged. The concentration of the sugar solution should reach 60 to 65%, which has a large osmotic pressure, so that the water in the microorganisms is precipitated by the sugar solution and is in a dehydrated (physiological drying) state and is inhibited. Therefore, candied fruit will not go bad easily even if it is not sealed. The soaking in sugar liquid can also prevent the oxidative loss of vitamin C in the fruit and improve the flavor of the finished product. However, excessive sugar content and excessive sweetness will affect the original taste of the finished product.

Therefore, it is required that the sugar content in the finished product must not only achieve the purpose of antisepsis and dehydration, but also maintain the flavor characteristics of the product to be just right. This is the key to the processing of preserved fruits.

The cooking of preserved fruit can be divided into two methods: one-time cooking method and multiple cooking methods. The candiing process is the key to determining the degree of sugar penetration into the pulp and the quality of the product. Therefore, the cooking method is determined according to the properties of the fruit.

One-time cooking method. Pour the pretreated raw materials and 60% concentration of sugar liquid into a pot and cook. Due to the penetration of sugar liquid, the water in the fruit is discharged, and the sugar liquid in the pot is gradually diluted. Sugar needs to be added accordingly. Until the sugar liquid concentration stabilizes at 65%, the preserved fruit cooked in this way will have the sugar liquid penetrate evenly, making it transparent and full. This method is suitable for making preserved apples, preserved fruits, preserved dates, etc. Because this kind of preserved fruit has low water content, large gaps between cells and tissues, and loose tissue, it is easy to absorb sugar liquid. As long as it is properly controlled, it is not easy to cook. After cooking, soak it in the original sugar liquid for a certain period of time (usually one day and night), take it out, filter out the sugar liquid, and then dry it.

Multiple cooking methods. The pretreated raw materials are first boiled in a sugar solution with a concentration of 30 to 40% for a few minutes, and then the sugar solution and raw materials are poured into the tank and soaked for 24 hours. The purpose of this cooking is to coagulate the protein in the fruit by heat, increase the permeability of the fruit cell wall, make it easier for external sugar liquid to penetrate into the fruit, destroy various enzymes in the fruit, and prevent the tannins from oxidizing and discoloring, which is beneficial to the process. Keep the colors bright. After soaking, increase the concentration of the sugar solution to 50 to 60%, boil for about 10 minutes, and then soak for 24 hours. The second cooking time is the key for the fruit to absorb the sugar liquid and increase the sugar content. Therefore, the sugar liquid concentration and cooking time must be well controlled. Remove the soaked raw materials, filter out the sugar liquid, and dry them on a drawer to lose part of the water. When the edges of the fruit curl up and small wrinkles form on the surface, you can cook for the third time. When the sugar liquid concentration stabilizes at 35 ~70%, boil for about 30 minutes, take out and filter out the sugar liquid, after cooling, squeeze the fruit into an oblate shape manually or mechanically, and then it is the finished product after drying. The multiple cooking method is suitable for making fruits with high water content such as peach preserves, pear preserves, and apricot preserves, because the cell walls of these fruits are thin and the tissues are dense. If the one-time cooking method is used for cooking for too long, not only will the sugar liquid not be easily It penetrates into the fruit and is easily boiled into paste, so it is cooked multiple times using a combination of boiling and pickling.

Due to the different types, sizes and properties of the fruits, the sugar concentration and cooking time are different. For example, if the peach "bowl" is larger than the apricot "bowl", the concentration of sugar liquid used is higher, and the cooking time is slightly longer. During the processing, the sugar liquid is recycled. The sugar liquid cooked in the first batch is used for the second batch of cooking, and the second batch of sugar liquid from the previous batch is used for the first cooking of the next batch.

Product packaging

The packaging of preserved fruits is of great significance in the business process. It is not only an important factor in beautifying the product and expanding sales, but also a powerful measure to protect the edible value of the product. Therefore, production and management must pay attention. At present, Beijing preserved fruits are packaged in wooden boxes made of wooden frames and plywood. The specifications vary and can generally hold a net weight of 25 kilograms. The packaging method is to line it with kraft paper, and then put a piece of sulfuric acid paper or wax paper (to prevent the finished product from getting damp, air-drying or being glued to the box), then put the finished product in bulk, cover it and nail it, and tie two iron hoops on the outside of the box to prevent the wooden box from falling apart. , causing losses. Although this packaging method is simple, it can easily cause the finished product to deform under pressure and stick to each other. If the moisture content increases and there is too much invert sugar, it will easily "bleed" during transportation during hot and humid seasons. You can also pack it in plastic bags first and then put it in wooden boxes to avoid "soaking" due to moisture. The other type is small packaging, which is packaged in small paper cones printed with bright and beautiful patterns, advertisements, and trademarks. The cardboard cones are lined with wax paper or cellophane. This kind of packaging is beautifully decorated, convenient for retail, and easy to carry.