لخّصلي

Fruit and vegetable processing relies heavily on auxiliary raw materials impacting their physical, chemical, sensory, and nutritional properties. Water is crucial, categorized into uses for processing (requiring potable quality), steam generation, and hygiene/cooling. Technological water quality is paramount; hard water can harden vegetables or affect sugar syrup gels, while soft water causes nutrient loss. Water hardness should be tailored to the product (e.g., 3° for beans, 5-9° for peas). Oxygen in water can cause corrosion, mitigated by boiling; neutral or slightly basic pH is ideal to prevent corrosion and toxicity. Steam generator water must be very soft and free of iron bacteria. Cooling and hygiene water should meet drinking water standards, with industrial water acceptable only for cleaning. Granulated sugar, characterized by uniform crystals and complete water solubility, is used in processing, with concentration measured by refractometers or areometers. Solubility varies with temperature; solutions are often prepared with heated water. Corn syrup (liquid glucose), used in marmalades, improves texture, shine, and reduces sweetness. Salt adds flavor and acts as a preservative, but impurities like magnesium chloride can cause issues. Salt solubility is only slightly affected by temperature. Vinegar, from various sources, preserves some vegetables. Citric, tartaric, and lactic acids are also used. Pectin preparations, classified as strong (>50% methyl ester) or weak (<50%), are used for gelling. Intensive sweeteners like Sunett (200x sweeter than sugar) and aspartame (180-200x sweeter) provide sweetness without calories, benefiting diabetics. However, they lack the textural and preservative properties of sugar, needing bulking agents or polyols. Sunett is stable under processing conditions, but sugar-free products require preservatives like potassium sorbate. Appropriate usage levels for Sunett and aspartame are detailed for various products, adhering to food laws' regulations in most countries.

Auxiliary raw materials used in fruit and
vegetable processing technologies play a
major role in the determination of their
physical and chemical characteristics,
sensory properties and nutritive value
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6.1 Water
⚫ water can be classified in three categories:

1. for technological utilization (when it comes into
   direct contact with raw materials and enters in the
   finished product's composition),


2. for steam generators and


3. for receptacle cooling, washing of equipment and
   general hygiene.
   6.1.1 Water for technological uses
   ⚫ Water coming into direct contact with the raw materials
   must be of drinking water quality in terms of its
   physico-chemical and microbiological conditions.
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   6.1.1 Water for technological uses
   ⚫ When very hard water is used for blanching
   vegetables some pecto-calcium and pectomagnesium
   complexes are formed which starts the hardening of
   vegetable tissues.
   ⚫ When fruit is processed in sugar syrup, the use of
   hard water for the syrup preparation could induce the
   formation of a pectin-sugar-acid gel facilitated by
   the medium pH and presence of calcium salts.
   ⚫ Soft water has negative consequences associated
   with mineral and hydrosoluble substances and losses
   during blanching of vegetables.
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   6.1.1 Water for technological uses
   ⚫ The water hardness is an essential factor when used
   as filling liquid for canned products; ideally, the
   hardness of the water should be adapted to the raw
   material species used for canning.
   ⚫ Thus a hardness of 3° is good for beans, 5° to 9° for
   green peas, green beans, and for F & V with a
   tendency to disintegrate should use even harder water.
   ⚫ In the technological process of cucumber preservation
   by natural acidification (lactic fermentation), water
   hardness about 10- 30° should be used.
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   6.1.1 Water for technological uses
   ⚫ Oxygen present in water can act as a corrosion factor
   in metal receptacles but this negative influence can be
   eliminated by preliminary boiling.
   ⚫ An important factor is pH. Water for canning must be
   neutral or slightly basic.
   ⚫ Acid water plays a major role in corrosion which is
   evident both on receptacles and on iron or copper
   equipment, where changes of product color will be
   induced.
   ⚫ More dangerous is the attack on lead pipes or to the
   mix used for can sticking and this can render the
   product toxic. For these reasons an acid water must be
   neutralized before use.
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   6.1.2 Water for steam generators.
   ⚫ Two main conditions must be fulfilled:


4. hardness has to be as low as possible, even zero,
   because precipitation of calcium salts can lead to the
   formation of ("crusts") in pipes and on equipment walls;


5. from a bacteriological point of view, the iron-bacteria
   must be eliminated with biological filters or oxidizing
   substances. This is necessary in order to avoid iron
   hydroxide formed on the inner walls of the pipes.
   ⚫ The elimination of iron-bacteria is also of importance
   for the water used in processing steps.
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   6.1.3 Water for receptacle cooling and
   general hygiene.
   ⚫ This should be of drinking water standard.
   ⚫ Where this is not available in sufficient quantity,
   the use of industrial water is acceptable but
   only for cleaning of production
   rooms/workshops.
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   6.2 Sweeteners
   6.2.1 Sugar
   ⚫ Physically there is icing, granulated and lump sugar.
   ⚫ In F & V processing, sugar is used only in its
   granulated form; this quality must be in the form of
   uniform crystals, white, shining and completely soluble
   in water.
   ⚫ Concentration of various sugar solutions can be
   rapidly measured by refractometer or with areometers
   graduated in various ways: Brix, Baumé, etc.
   ⚫ The correspondence between these measuring units
   and quantity of water by volume unit is indicated in
   Table 6.2.1.
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   TABLE 6.2.1 Physical characteristics of sugar solutions
   Sugar in solution Specific weight deg.Bé
   deg.Bx
   (K/100 g)
   g/l
   Boiling
   temperature °C
   Sugar solubility in water is dependent upon
   temperature; for example, in order to obtain a
   saturated solution, one must dissolve 2040 g in one
   liter of water at 20° C and 4870 g at 100° C.
   ⚫ Taking into account this temperature related solubility,
   in practice the majority of sugar solutions are
   prepared by heating the water.
   6.2.2 Corn syrup (liquid glucose)
   ⚫ Corn syrup is obtained industrially by acid or
   enzymatic starch hydrolysis, using as starting raw
   materials maize (corn) or potatoes.
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   6.2 Sweeteners
   6.2.2 Corn syrup (liquid glucose)
   ⚫ In fruit processing, mainly in marmalades, it is
   possible to use corn syrup. The average composition of
   this corn syrup is of about 32-40% glucose, about 40%
   dextrins and 18-20% moisture. Sweetening power is
   50% compared with sucrose.
   ⚫ In a 10 -20% proportion with sucrose, addition of corn
   syrup has certain advantages:


6. it improves the shine and texture of marmalade;


7. it prevents "sugaring" defect and


8. it reduces the too sweet taste of finished products
   obtained with sugar alone.
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   6.3 Salt
   ⚫ Salt is used in order to give to the finished
   products a specifically salty taste and as a
   preserving substance.
   ⚫ From a chemical point of view the term salt
   means sodium chloride but in practice the
   product is never in a pure state.
   ⚫ The presence of a significant quantity of
   magnesium chloride increases the
   hygroscopicity, gives a bitter taste and can
   induce corrosion of receptacles.
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   6.3 Salt
   ⚫ From a microbiological point of view, salt it is
   not a sterile product but on the contrary
   contains various micro-organisms, mainly
   halophil bacteria.
   ⚫ Salt solubility is only slightly influenced by
   temperature (0.360 kg/1 at 20° C and 0.390
   kg/l at 100° C).
   ⚫ Correspondence between specific weight
   and salt content of salt solutions at 15° C is
   shown in Table 6.2.2.
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   TABLE 6.2.2 Physical characteristics of salt solutions
   NaCl content deg.Bé Specific weight
   g/100 g
   Acetic acid. Acetic acid is in use as solutions of
   various concentrations which are known under the
   generic name of vinegar. Vinegar can be obtained:
   a) from wine, alcohol, cider, beer, etc. by fermentation;
   b) by dilution of acetic acid obtained by dry wood
   distillation or by synthesis.
   ⚫ vinegar is used and acts as a preservation agent for
   some vegetables: cucumbers, acidified vegetables,
   etc.
   ⚫ Citric acid
   ⚫ Tartaric acid
   ⚫ Lactic acid
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   6.5 Pectic preparations
   ⚫ In fruit processing there many preparations
   and mixes known as "pectin" are used as
   liquid or powder extracts.
   ⚫ The pectic preparations are classified as:


9. strong pectins (>50% methyl ester group) obtained
   from apples or citrus fruit peel; this category gives gels
   rich in sugar;


10. weak pectins (< 50% methyl ester group) which
    gives gels with low proportion of sugar or even without
    sugar but with the addition of calcium salts.
    ⚫ The fruit industry uses mainly strong pectins.
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    6.6 Intensive sweeteners
    ⚫ Sweeteners are making an important contribution to the
    manufacture giving "sweet" without "high-calorie".
    ⚫ Sweeteners enable diabetics to enjoy sweet tastes
    without changing their lifestyle.
    ⚫ Sunett is the trade mark of Hoechst AG for its high
    intensity sweetener ; it is about 200 times sweeter than
    sugar.
    ⚫ blends of Sunett with other sweeteners, e.g. aspartame,
    results in a taste that is particularly pleasant.
    ⚫ Sunett is applied to beverages (fruit syrups and juices,
    carbonated beverages, etc.).
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    6.6 Intensive sweeteners
    ⚫ Carbohydrates do not only provide the sweet taste;
    but also act as bulking or texturing agents and as
    preservatives by reducing the water activity.
    ⚫ This not available in Sunett and other sweeteners, so
    they must be combined with other bulking agents or
    sugar substitutes (for example polyols: sorbitol, mannitol)
    ⚫ Drinks based on fructose and Sunett are suitable for
    diabetics.
    ⚫ Amounts of up to 200 mg/l Sunett are often adequate
    as a single sweetener for the popular types of fruit
    nectars.
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    6.6 Intensive sweeteners
    ⚫ Sunett can withstand pasteurization, hot filling and
    aseptic filling without any loss of sweetness.
    ⚫ Sugar contributes a great deal to the texture and
    stability of conventional jams and marmalades.
    ⚫ Sugar-free jams and marmalades containing
    sweeteners are more susceptible to
    microorganisms than sugar-containing products.
    ⚫ it is advisable to add 0.05-0.1% potassium sorbate
    as a preservative,
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    6.6 Intensive sweeteners
    ⚫ For sugar-free jams and marmalades, a range of
    500-2000 mg Sunett/kg of the finished product are
    appropriate.
    ⚫ It is advisable to add Sunett in the form of an
    aqueous stock solution towards the end of the
    boiling process to insure dispersed throughout the
    whole batch.
    ⚫ Fruit preserves. Sunett can be used for the
    production of sugar-free or sugar-reduced fruit
    preserves.
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    6.6 Intensive sweeteners
    ⚫ NutraSweet(r) is the commercial name of aspartame.
    ⚫ which can be used in the most foods in order to give the
    same taste as sugar.
    ⚫ Aspartame is about 180 to 200 times sweeter than
    sucrose (sugar) and this value depends on pH,
    temperature and the type of flavor.
    ⚫ Aspartame can be used as mentioned above in a mix
    with Sunett or alone in all sugar-free or calorie-reduced
    fruit jams, marmalades and preserves.
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    6.6 Intensive sweeteners
    Both Sunett and Aspartame are widely accepted by food
    laws in the majority of countries. The following are the
    main fruit products where Sunett is an accepted
    sweetener:
    ⚫ low-joule prepared jelly: max. 500 mg/kg;
    ⚫ canned fruit without added sugar: max. 500 mg/kg;
    ⚫ beverages including calorie-reduced fruit nectars: max. 600
    mg/l;
    ⚫ calorie-reduced jams;
    ⚫ canned fruit and vegetables, fruit puree, jams and
    marmalades;
    ⚫ juices, nectars and juice based beverages;
    ⚫ jams, marmalades and related products: max. 300 mg/kg.