Manufacturing Jams and Fruit Preparations

In dairy industry, FF&VV are added to the dairy white base via fruit or vegetable preparations.

A fruit preparation contains typically 50% to 60% of fruit (pieces, juices, puree), 20% to 30% of sugar, water (10% to 15%), stabilizers (such as starch, pectins), acidity regulators, colorants and flavorings for a better appeal, and can also be fortified with vitamins, fibers, prebiotics, phytosterols, omega-3, and minerals in order to reach higher nutritional value for a specific market segment.

The various ingredients are metered or weighed into the premix vessel, which is jacketed for the preheating of the mix and dissolution of sugar. A scraped surface agitator and baffle combination in this vessel give both good heat transfer and rapid, but gentle, blending together of the various ingredients.

After mixing, the premix is drawn under vacuum into the vacuum-cooking vessel. This has zoned dimple-panel heating elements, so that there is efficient heat transfer using the low-speed scraper agitator, without problems of burn-on, even when preparing part batches. Rapid vacuum evaporation takes place at 60° to 65°C, and the vapor is separated in a cyclone separator, with any product carryover being returned to the vessel (Somogyi et al., 2005).

Normally, the vapor is condensed in a surface and may be recovered for use in recipe make-up, in-place cleaning, and so on; however, where required, a partial condensation volatile recovery system may be added for recovery of volatile flavorings.

After completion of this rapid, low-temperature cooking process, the product is transferred, using top-filtered air pressure to the buffer tank. From here, it is pumped to an APV scraped surface heat exchanger flash pasteurizing plant prior to filling. This stage is necessary because the low-temperature vacuum evaporation may not be effective in killing any spoilage microorganism present in the ingredients. The rapid pasteurization usually takes place at 85° to 95°C, depending on the TS and acidity of the recipe. Pasteurizing is under pressure to avoid any volatile loss and, after a short hold time, is followed by rapid cooling to the required filling temperature (for fruit jam with low pH and high sugar content it can be ambient temperature) (Somogyi et al., 2005).

This process may also be adapted for use during the fruit harvesting period for the pasteurization of fruit pulp or fruit in syrup, which can then be filled into aseptic tanks or stainless steel containers for later use in recipes (Somogyi et al., 2005) even if generally it is preferred the preparation of IQF (individually quick frozen) fruit pieces that can be stored 24 months at -20°C (or lower).

Fruits used for making fruit preparations must be conveniently prepared—for example, removing seeds, pits, and stalks from apricots, cherries, grapes, nectarines, peaches, plums, crushing, and refining the fruit for obtaining a puree (eventually concentrated via evaporation or freeze concentration), cutting the fruit for obtaining cubes or pieces.

In case of soft fruit such as the berries (particularly strawberries and raspberries), fruit can be candied with sugar syrup in order to obtain a harder consistence/firm- ness and a better mechanical resistance to the stress during the process.

In recent years, fruit preparations have been enriched with delicious inclusions, such as crispy, extruded cereals covered with chocolate or chocolate splits (see Figure 1.3.2.1). In order to maintain crunchiness, crispies are totally covered with a thin layer of vegetable fat that prevents moisture entrance; obviously, those inclusions must be aseptically added to the pasteurized fruit preparation after or during the cooling phase, following the heat treatment.

Batch process flow for fruit preparations with flavors

Figure 1.3.2.1 Batch process flow for fruit preparations with flavors.

 
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