Lemons

Lemons
Lemons trees may be grown from nursery root stock, but mostly the fruit is grown on graft made on stock of the sour orange.

Once established, the trees may bear fruit for many years. Since the trees, and particular the fruit, are damaged by freezing temperatures, they may have to be protected in cold weather.

Lemons are produced in United States, mainly in California and Arizona.

They are harvested when the skin in green or silver in color and ripened to a yellow color in bins, the air of which contains some ethylene.

Most lemons are marketed in the fresh state, and as such are handled in much the same manner as are grapefruit.

Cooled to about 32 degree F and held at this temperature, fresh lemons have a storage life of 1 – 4 months.

Some lemon juice is prepared and frozen as a lemonade concentrate. The fruit is washed, sized and inspected, after which the juice is extracted and screened.

Sugar is added to provide a soluble solid to acid ration of 14:1 – 19:1. The mixture is then evaporated at low temperature under vacuum to provide a 5:1 concentrate.

The screen pulp (which contains some liquid) is then added to the concentrate to provide 2.4 – 4% pulp by volume.

The concentrate mixture is frozen to a slush having a temperature of 25 degree F ( - 3.9% degree C) in a refrigerated heat exchanger.

The slush is filled into cans, the cans sealed and conveyed through a cold air tunnel until the product is cooled to a temperature of – 18 degree F (-27 degree C) or lower.

Some lemon juice is evaporated to a concentration of about 2:1 and packaged in glass or plastic containers with 0.1% sodium benzoate. Pulp and sugar are not added to this product, which requires no refrigeration. Pectin is manufactured from lemon peel as in the case of grapefruit.
Lemons

How grape juice is manufactured

How grape juice is manufactured
The Concord variety is chiefly used for the manufacture of grape juice. The grape are washed in acid or alkaline solution, then in water to remove spray residues, then destemmed and crushed by mechanical means. The crushed grapes are heated to about 180 F to extract pigment from the skins, after which the heated materials subjected to mechanical pressure while enclosed on cotton press cloths. The juice is then filtered, pasteurized by heating to 1790 F, and stored in bulk in covered tanks at about 40 F. This provides for the separation of tartaric acid slats. The juice is then siphoned off from the tartrate and treated with enzymes, which break down pectin, or with casein for purposes or clarification. It is then filtered and bottled. The bottles are capped and then pasteurized by heating in water at 170 F for 30 min.

To produce grape juice concentrate, grape juice is subjected to heat and evaporation until concentrated. Volatile components can be recovered from the process, and they can be added back to the concentrate. The concentrated juice may be frozen in retail sized containers, or it may be shipped in large tanks to food processors for remanufacturing process.
How grape juice is manufactured