Preserves fruit

Preserves and fruit juices Much use is made of sulphur dioxide to preserve fruit pulps and juices, and for these applications molybdenum-bearing steels should be specified. 

Sulfur dioxide is produced by burning sulfur in air for preserving fruit, or by reacting sodium bisulfite in water as part of the process to make products such as wine. 

There is a recent trend towards simultaneous CE separations of several classes of food additives. This has so far been applied to soft drinks and preserved fruits, but could also be used for other food products. An MEKC method was published (Lin et al., 2000) for simultaneous separation of intense sweeteners (dulcin, aspartame, saccharin and acesulfame K) and some preservatives (sorbic and benzoic acids, sodium dehydroacetate, methyl-, ethyl-, propyl- and isopropyl- p-hydroxybenzoates) in preserved fruits. Ion pair extraction and SPE cleanup were used prior to CE analysis. The average recovery of these various additives was 90% with good within-laboratory reproducibility of results. Another procedure was described by Frazier et al. (2000b) for separation of intense sweeteners, preservatives and colours as well as caffeine and caramel in soft drinks. Using the MEKC mode, separation was obtained in 15 min. The aqueous phase was 20 mM carbonate buffer at pH 9.5 and the micellar phase was 62 mM sodium dodecyl sulphate. A diode array detector was used for quantification in the range 190-600 nm, and limits of quantification of 0.01 mg/1 per analyte were reported. The authors observed that their procedure requires further validation for quantitative analysis. 

The use of S02 for preserving fruit juices, syrups, concentrates, and purees is particularly attractive in regions with warm climates and where products must be stored in bulk prior to processing. In these situations, the SO> concentration will range between 350 and 000 ppm. High sugar concentrations require higher levels of S02. For optimal effectiveness, the pH of some products has to be reduced. 

These include mainly crystallised fruits, preserved fruits, jams, chocolates, sweetmeats, biscuits, effervescent citrate of magnesia, honey, condensed milk, liqueurs and sweet wines. Certain of these products are dealt with in other places, condensed milk, liqueurs and sweet wines, for instance, in the chapters dealing respectively with milk, spirits and liqueurs, and wines. The others are treated below, special attention being paid to the determination of the sugars. 

To ascertain the quantity of sugar (saccharose) used in the preparation of the preserved fruit, from the total sugar (invert sugar x 0 95 plus saccharose) contained in the sample must be deducted the natural sugar (also calculated as saccharose) due to the quantity of fruit in the sample. For this purpose it is, of course, necessary to know the saccharine contents of different fruits, so that an analysis of fruit of the same quality preserved in water in the same conditions as in the syrup must be made. 

Doesburg, J. J. (1965). Pectic Substances in Fresh and Preserved Fruits and Vegetables. Communication No. 25, I.B.V.T., Wageningen, The Netherlands. 

Sugar is also a natural substance that has been used as a preservative. However, before sugar was available, honey was used to preserve fruits and meats and in breads that were used as traveling food. The earliest jams date from pre-Roman times, when honey was combined with fruit and spices and left to dry in the sun. 

Kitchen chemistry. Sucrose is commonly used to preserve fruits. Why is glucose not suitable for preserving foods See answer... 

For thousands of years, perishable foods such as fish, olives, and vegetables have been preserved in salt or brine. The high salt concentration is hypertonic to bacteria cells, and kills them by dehydration before they can cause the food to spoil. Preserving fruit in sugar (jams, jellies) works on the same principle. 

When sulfur is burned in air, it reacts with oxygen to form sulfur dioxide, which is used to preserve fruit and as an antibacterial agent. Sulfur dioxide released into the atmosphere reacts with water vapor to form one of the acids in acid rain. More than 90% of the sulfur dioxide produced is used to make sulfuric acid. This inexpensive acid is used by so many industries that the amount of it produced can indicate the strength of an economy. About half the sulfuric acid produced is used to make fertilizers. Products ranging from steel to paper to paints also depend on this acid. 

Sulfur dioxide (SO2) is a colorless and nonflammable gas with a pungent odor. It is used commercially to preserve fruits and vegetables and as a disinfectant in food production. It is also used in bleaching straw and textiles. Liquid SO2 can be produced by pressurizing the gaseous form and then used as a solvent. Sulfur dioxide is also a primary component of air pollution. 

Tamarindus. Tamarind. Tamarindus Indica. W. III. 577. Fruotus conditus. The preserved fruit. 

Canned and Preserved Fruits 407 Organic loading, suspended solids, pH, oil and grease... 

Food chemistry is an old practice, but the occupation of food chemist is only about 150 years old. In fact, the first prehistoric person to place raw meat in a cold cave or put fruits out to dry in the sun was in a way a food chemist. But it would be many years before we understood why cold keeps meat fresh longer, or how the sun preserves fruit through drying. 

Doesburg, J.J. Pectic substances in fresh and preserved fruits and vegetables IBVT-Communication No. 25. Institute for Research and on Storage and Processing of Horticultural Produce Vageningen, 1965. 

Camphor Water. Take i ounce nf camphor iiud cucloso it with a glass marblo in a muslin bag put this into a wide-mouthed bottle, such a one as is used for preserved fruit. Now fill up the bottle with water that has boiled a few minutes ajid has been allowed to become cold. The glass marble is used to keep tho camphor from floating, which it otherwise would do. After about 3 days tho water will become saturated with the camphor, ami may bo poured oflF as required. A wine-glassful is a dose. It is very useful os on anti-spasmodic in hysteric and nervous affections. 

Sulfurous acid, calcium salt (1 1). Used as a dechlorinating agent for water. Used to preserve fruit juices, in paper processing and sugar manufacture, [dihydratej slightly soluble in H2O, EtOH. 

The slowness with which comparatively cheap fruit juices have come into use is due largely to the lack of satisfactory methods of preserving fruit juices without alteration in flavors. 

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