Purpose:

The purpose of this experiment was to analyze different fruit juice labels and to compare properties of these fruit juices with each other, and to inquire about fruit juice standards.

Preparation:

The principal preparation steps are washing and sorting. Mechanically harvested tomatoes are usually thoroughly washed by high-pressure sprays or by strong-flowing streams of water while being passed along a moving belt or on agitating or revolving screens. The raw produce may need to be sorted for size and maturity. Sorting for size is accomplished by passing the raw tomatoes through a series of moving screens with different mesh sizes or over differently spaced rollers. Separation into groups according to degree of ripeness or perfection of shape is done by hand; trimming is also done by hand.

Peeling and Coring:

Formerly, tomatoes were initially scalded followed by hand peeling, but steam peeling and lye peeling have also become widely used. With steam peeling, the tomatoes are treated with steam to loosen the skin, which is then removed by mechanical means. In lye peeling, the fruit is immersed in a hot lye bath or sprayed with a boiling solution of 10 to 20 percent lye. The excess lye is then drained and any lye that adheres to the tomatoes is removed with the peel by thorough washing. Coring is done by a water-powered device with a small turbine wheel. A special blade mounted on the turbine wheel spins and removes the tomato cores.

Filling:

After peeling and coring, the tomatoes are conveyed by automatic runways, through washers, to the point of filling. Before being filled, the can or glass containers are cleaned by hot water, steam, or air blast. Most filling is done by machine. The containers are filled with the solid product and then usually topped with a light puree of tomato juice. Acidification of canned whole tomatoes with 0.1 to 0.2 percent citric acid has been suggested as a means of increasing acidity to a safer and more desirable level. Because of the increased sourness of the acidified product, the addition of 2 to 3 percent sucrose is used to balance the taste. The addition of salt is important for palatability.

Exhausting:

The objective of exhausting containers is to remove air so that the pressure inside the container following heat treatment and cooling will be less than atmospheric. The reduced internal pressure (Vacuum) helps to keep the can ends drawn in, reduces strain on the containers during processing, and minimizes the level of oxygen remaining in the headspace. It also helps to extend the shelf life of food products and prevents bulging of the container at high altitudes. Vacuum in the can may be obtained by the use of heat or by mechanical means. The tomatoes may be preheated before filling and sealed hot. For products that cannot be preheated before filling, it may be necessary to pass the filled containers through a steam chamber or tunnel prior to the sealing machine to expel gases from the food and raise the temperature. Vacuum also may be produced mechanically by sealing containers in a chamber under a high vacuum.

Sealing:

In sealing lids on metal cans, a double seam is created by interlocking the curl of the lid and flange of the can. Many closing machines are equipped to create vacuum in the headspace either mechanically or by steam-flow before lids are sealed.

Heat Sterilization:

During processing, microorganisms that can cause spoilage are destroyed by heat. The temperature and processing time vary with the nature of the product and the size of the container. Acidic products, such as tomatoes, are readily preserved at 100°C (212°F). The containers holding these products are processed in atmospheric steam or hot-water cookers. The rotary continuous cookers, which operate at 100°C (212°F), have largely replaced retorts and open-still cookers for processing canned tomatoes. Some plants use hydrostatic cookers and others use continuous-pressure cookers.

Cooling:

After heat sterilization, containers are quickly cooled to prevent overcooking. Containers may be quick cooled by adding water to the cooker under air pressure or by conveying the containers from the cooker to a rotary cooler equipped with a cold-water spray.

Labeling And Casing:

After the heat sterilization, cooling, and drying operations, the containers are ready for labeling. Labeling machines apply glue and labels in one high-speed operation. The labeled cans or jars are the packed into shipping cartons.

Results And Calculation:

Determination of Ascorbic Acid:

10 ml fruit juice was used for ascorbic acid determination Amount of ascorbic acid (g.) = 0, 0886 * V (ml) * N (Normality of iodine sol’n)

Amount of ascorbic acid = 0, 886 * 0, 4 ml * 0, 1 N =3, 544 * 10-3 g

Formal index:

1st step            pH = 8, 5 à   spent 0, 1 N NaOH 15, 0 ml

2nd step            pH = 8, 5 à   spent 0, 1 N NaOH   3, 7 ml

For 25 ml,                   18, 7 ml NaOH

For 100 ml                   x = 74, 8 ml NaOH formal index.

Brix:

Brix was measured with refractometer.

Brix = 13

pH:

pH was measured with pHmeter.

pH = 3, 09

Discussion:

The general process of fruit juice making is simple. The fruit are picked, washed and then sized by milling, crushing or cutting. The juice is then extracted using either juice extractor or separation equipment. If necessary, the must is then clarified. 

In this experiment, we analyzed some different types of fruit juice according to their pH, brix, formal index, ascorbic acid.

These tests showed us that some different characteristics of fruit juice are used to determine quality level. pH is important quality parameter for fruit juice. At low pH, microbial growth decreases and shelf life of fruit juice increases. All fruit juices have low pH according to their types. Brix gives information us about soluble solid content, and defines the juice strength. In addition, it is most important quality parameter in juice because high brix value shows that high fruit content in juice. Formal index again crucial parameter for fruit juice because it gives information about natural fruit juice, which are prepared fromsynthetic volatile oils. Lastly; ascorbic acid is important parameter and it is an antioxidant and prevent spoilage of fruit juice at the same time it is a vitamin for our health. 

Furthermore; water is crucial for fruit juice making. Water quality is critical, if in doubt use boiled water or add one tablespoon of bleach to each gallon of water to sterilize it. If water is cloudy, a water filter should be used. In addition, if hard water is used in fruit juice the sensory properties of fruit juice changes. And also; the temperature and time of heating are critical for achieving both the correct shelf life of the drink and retaining a good colour and flavour. A thermometer and clock are therefore needed.

After analyses of fruit juice; pH except dimes apple juice other juice are appropriate for TSE values. And also each type of mark different pH values at same juice. Brix dimes and tamek cherry had highest soluble solid content according to data. And also pınar mixture and cappy apple had least soluble solid content. TSE allow minimum 10% solid content in juices and obtaining values were appropriate for TSE value. Formal index is greater than 15% and all juices were appropriate for TSE value. Finally; ascorbic acid value is minimum 20 mg / 100ml according to TSE. However; our values were lower than TSE value. Maybe; during the experiment any thing was made as mistaken.

These factors are important because a customer will stop buying the products if the quality varies with each purchase.