Detailed Explanation of the Development Process for Golden Sun Apricot Jam

Golden Sun apricot is a European apricot variety introduced by the Shandong Institute of Pomology in 1993. The fruit surface is smooth, the background color is golden yellow, and the sunny side has a red blush, making the fruit color very attractive. The flesh is yellow, fine and juicy, with few fibers, containing 14.7% soluble solids, 13.1% total sugar, and 1.1% titratable acid. The average single fruit mass is 70g, the stone is free, and the edible rate reaches 96.8%. The fruit matures at the end of May and has the ability to set fruit parthenocarpically. It is early-bearing, high-yielding, and stable-yielding, and is resistant to pests and diseases with strong adaptability.

In view of the excellent comprehensive traits of Golden Sun apricot, in newly developed apricot orchards in recent years, Golden Sun accounts for about 50% of new varieties. According to statistics, its cultivation area has reached 20,000 hectares, of which Shandong Province accounts for about 1/3 of the total cultivation area, and in some areas Golden Sun apricot has become the local leading industry. Golden Sun apricot can not only be eaten fresh, but canned Golden Sun apricot is also very popular in the market. Because the ripening season of Golden Sun apricot has high temperatures and the harvest period is relatively concentrated, deep processing is therefore very necessary.

1. Raw Materials and Equipment

Golden Sun apricot, white granulated sugar, NaHSO3, salad oil, jacketed kettle, torsion balance, handheld refractometer, thermometer, sterilizer.

2. Process Flow

Raw material selection → washing → peeling → trimming, cutting, pitting → pre-boiling → ingredient preparation and sugar preparation → sugar addition and concentration → bottling → sealing → sterilization → cooling → finished product → inspection → finished product.

3. Technical Key Points

(1) Raw material selection requires grading according to differences in the maturity (or appearance color) of Golden Sun apricot, and processing them separately. According to maturity, they can be divided into 3 categories: the first category is fully mature fruit with golden yellow color and slightly soft; the second category is fruit at 80% to 90% maturity with golden yellow color and firm flesh; the third category is fruit below 80% maturity with yellow color and hard fruit. After grading the raw materials, remove fruit with pests and diseases and other rotten fruit.

(2) Raw material pretreatment includes washing, trimming, cutting, and pitting. Wash the Golden Sun apricots or soak them in a 0.5% mass fraction hydrochloric acid solution for 5min to 10min to remove pesticide residues on the peel (treat according to the pesticide use situation of different orchards), then rinse clean with water, and soak in a 3% to 5% mass fraction NaOH solution for 3min to peel. After alkali soaking treatment, rinse and rub the Golden Sun apricots with clean water to make the peel fall off, then pour them into about 0.2% hydrochloric acid solution to neutralize for 2min (which also has a color-protecting effect). Fruit at 90% maturity or above needs manual peeling, and the peeled fruit is cut in half and pitted. Fruit with high maturity does not need cutting, while fruit with low maturity needs appropriate cutting.

(3) Pre-boiling Place the treated Golden Sun apricots in a jacketed kettle for pre-boiling. Through experiments, Golden Sun apricot fruit pieces need to be added with water accounting for 2% to 5% of their mass and pre-boiled in the kettle for 5min to 10min, until the flesh softens. After the raw materials are put into the kettle, add NaHSO3 accounting for 0.05% to 0.1% of the raw material mass.

(4) Ingredient preparation and sugar preparation Weigh the Golden Sun apricot fruit mass and sugar mass in a ratio of 1:0.75 and set aside. In addition, the ratio should be determined from low to high according to differences in the maturity of the Golden Sun apricot raw materials.

(5) Sugar addition and concentration Add the weighed white granulated sugar directly to the pre-boiled fruit flesh and heat to concentrate. Before boiling, high heat can be used to reduce the cooking time. Pay attention to controlling the heat and stir continuously to accelerate water evaporation, speed up concentration, make all parts of the kettle heated evenly, and prevent burning. During the concentration process, sugar should be added in portions, which is also conducive to water evaporation, avoids excessively long concentration time, and prevents the sugar color from darkening and affecting jam quality.

At the initial stage of concentration, because the raw materials contain a large amount of air, a large amount of foam will be produced, so a small amount of salad oil can be added to eliminate the foam and ensure normal water evaporation. The concentration time should not be too long, as too long will affect the color, aroma, and taste of the jam; too short will result in insufficient invert sugar formation, causing sugar crystallization during storage. Generally, after the raw materials boil, concentrate for another 30min to 45min.

Generally speaking, the end point of concentration is indicated by one of the following 3 phenomena: ① soluble solids reach 55% to 60% or more; ② when lifted with a wooden board, the jam falls in sheets; ③ the core temperature of the jam reaches about 105°C. Any one item can be selected as the basis for judging the end point of concentration.

(6) Bottling and sealing After concentration, while hot, put the jam into sterilized bottles, keeping the jam temperature above 85°C, and the faster the filling speed the better. When bottling, leave a 5mm headspace, and seal immediately after filling. Keep the bottle mouth clean during filling to avoid contamination with jam. If contaminated, immediately wipe clean with a sterilized clean dry cloth and then quickly cap and seal.

(7) Sterilization and cooling After sealing, immediately put the bottles into the kettle and sterilize with steam. Raise the temperature to 100°C within 5min, hold for 20min, then cool in stages to about 37°C, wipe off water droplets on the outside of the bottles, and they can be stored.

4. Finished Product Characteristics

The jam made from Golden Sun apricot is golden yellow and semi-transparent, glossy, bright and attractive, uniform and consistent, sweet and sour and palatable, with a relatively rich fresh apricot fragrance, no burnt or other off-flavors, and the jam body is viscous and can retain some fruit pieces.

5. Quality Indicators

(1) Sensory indicators Color, golden yellow; moderately sweet and sour, soft mouthfeel, with the fresh fragrance of apricot; semi-transparent viscous form, does not secrete juice, and no sugar bleeding phenomenon.

(2) Physicochemical indicators Soluble solids below 50g/100g, tin content below 0.2g/kg, lead content below 0.002g/kg.

(3) Microbiological indicators Total bacterial count below 100/g, coliform count below 30/100g, pathogenic bacteria must not be detected.