Detailed Explanation of the Processing Technology and Production Method of Carambola (Starfruit) Jam

(1) Process flow

Raw material selection and handling → heating and softening → mincing → blending → heating and concentration → canning and sealing → sterilization and cooling

(2) Explanation of key operation points

(1) Raw material selection and handling: Select fruits that are 80-90% ripe, fresh, of normal flavor, free from pests and diseases, and free from rot. Wash them, and cut off the stem and blossom ends and the ridges. The prepared carambola must be strictly prevented from piling up and discoloring.

(2) Heating and softening: Immerse the carambola in boiling water for 2-3 minutes to soften it, so as to facilitate pulping and sugar syrup penetration, and to destroy its enzyme activity and prevent discoloration.

(3) Mincing and pulping: Put the softened fruit pulp into a pulping machine and crush it into a pulp.

(4) Blending: Carambola contains little pectin and a relatively high acid content. The pH value of the pulp after pulping is low, generally pH 1-2. Use cool boiled water to adjust the pulp so that the pH reaches 3-3.2, then press it (the juice after pressing can be used as concentrated fruit juice and soda). The jam after pressing has a moderate water content, and the weight of the pulp is the same as the weight of the original pulp after crushing. Keep the pulp amount at 40%-50% of the total ingredient amount, granulated sugar at 45%-60% (of which starch syrup may be used in an amount of 20% or less of the total sugar amount), and agar added at 0.5%-0.7% (first dissolve the agar in 20 times its weight of hot water, then filter).

(5) Heating and concentration: Take 1/3 of the sugar syrup and the jam and heat and boil them in a double-layer pot for 10-20 minutes to promote softening and evaporate part of the water, then add the remaining sugar liquid in batches. When the concentration reaches a soluble solids content of 60%-65%, add the agar liquid and stir evenly, then immediately remove from the heat and fill into cans. During the softening and concentration process, appropriate stirring is needed to prevent burning in the pot.

(6) Canning and sealing: The jam temperature is required to be above 85°C, and the jam must be strictly prevented from dirtying the cans. After filling, immediately cover and seal, and immediately sterilize.

(7) Sterilization and cooling: Boil the cans in 100°C boiling water for 5-15 minutes, then cool them in stages to 38°C.

(3) Product quality indicators

The jam body is viscous and does not flow or spread on a flat surface, does not secrete juice, and has no sugar crystals; it has no burnt or scorched taste or other off-flavors, but has the unique flavor of carambola; the soluble solids content, measured by refractometer, is not less than 65%; the total sugar content, calculated as invert sugar, is not less than 57%.