Integrierte Vermeidung und Verminderung der Umweltverschmutzung

Chapter 2
2.2.3.4 Frozen fruit
The freezing of fruits is a major preservation method in its own right and it is widely used to
preserve fruits which are to be further processed, e.g. for the manufacture of jam. Fruits
intended for freezing are generally washed and inspected before being individually quick frozen
(IQF), or packed in syrup or pureed before freezing. Typical fast freezing methods involve
direct contact with a cooled solid, e.g. band or drum freezers, direct contact with cooled air or
other gaseous mixtures, e.g. blast air, fluidised bed and spiral freezers, direct immersion in a
cooled liquid, e.g. brine freezers, or cryogenic freezers. The process for deep-frozen fruit and
vegetables is shown in Figure 2.6.
Figure 2.6: The process for deep frozen fruit
2.2.3.5 Fruit preserves
Raw fruit and vegetables
Truck weigher
Tipping bunker
Washing
Sorting
Cutting if required
Blanching
Deep freezing
Packing
Deep-frozen fruit and vegetables
Preserving is the manufacture of jams, jellies, marmalades and mincemeat. It is essentially the
combining of fruits and sugar with subsequent cooking. It produces a tasty product of a
sufficiently high sugar content, low aw value, and with a satisfactory shelf-life retention quality.
A pasteurising treatment is applied at 85 ºC or above. The jams are made using pulp and fruit
juice, e.g. citrus for marmalade, and clarified juice for jellies. The basic ingredients of a
preserve are fruit, sweetening agents, typically sucrose and/or various sugar syrups; acids,
typically citric or malic acid; buffers such as trisodium citrate; fats, in curds/mincemeat; citrus
peel, for mincemeat and marmalade; gelling agents, usually pectin and anti-foaming agents –
when using frozen or sulphited fruits. In a typical process, the fruit usually arrives pre-prepared
either frozen or sulphited. The prepared fruit, pectin, sucrose, glucose syrup and other small
ingredients are then blended together in a mixing vessel. The mix is boiled either at atmospheric
pressure or under vacuum, using batch or continuous methods. After boiling, the jam is filled
into containers which vary from individual portions to bulk tank for bakery use.
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