FE475 Analysis of Tomato Paste




FE475 Food Quality Control Laboratory



The purpose of this experiment was to analyze different tomato paste labels and to compare properties of these tomato pastes with each other, and to inquire about tomato paste standards and adulteration


Industrial tomato products users should rigorously evaluate tomato products suppliers based on long-term, fundamental characteristics important to users intent on achieving advantageous values.

When tomato products prices are high, there is always expansion; when there is oversupply creating lower prices, there is always contraction. Do all new entrants to the industrial tomato products industry offer product quality and cost advantages to users through improved design, technology and organization? Which suppliers may quit the business and terminate production of tomato products? What are your concerns in evaluating industrial tomato products supply?

It takes only one page to outline intent, and even less to say, “We are the foremost industrial tomato products supplier in our industry.” However, it takes considerably more to discuss the criteria that will enable the discriminating tomato products user to rigorously evaluate our commitment to achieve a high level of performance. The following discussion applies to the production of tomato paste; however, most factors also apply to diced tomatoes.

(A) Tomato Product Quality that not only meets the user’s specifications, but is consistent from container to container.

(1) Higher quality fresh tomatoes;
(2) Faster and gentler handling of fresh tomatoes from field to hot-break tank;
(3) Good hot-break temperatures followed by lower evaporation and sterilization process temperatures;
(4) Faster movement of product through the process, decreasing the time product is exposed to elevated temperatures, and;
(5) Maximum blending of fresh tomato loads and product through a dedicated process line to equalize the naturally varying quality of incoming fresh tomatoes.

(B) Tomato Product Price that provides a competitive edge in favor of the user.

(C) A Tomato Product Supplier intently responsive to the user’s need for:

(1) prompt, accurate invoicing and shipping service;
(2) sound technical support service for product issues;
(3) quick, authoritative decisions on issues impacting the business relationship;
(4) knowledge of technologies and industry forces impacting their business and the structure of the tomato industry, and;
(5) personnel and ownership intent on maintaining themselves at the forefront of tomato processing–as innovators and true professionals.

(A) Tomato Paste Quality.

The best quality is that which consistently meets the customer’s specifications. However, most customers’ specifications have acceptable parameters rather than absolute targets. For example, viscosity may be specified as 5 to 7 cm. Bostwick, instead of 6 cm. This is due primarily to historical technological limitations, as well as the relative acceptance of product variability by the consumer. However, if such technology and ability were available to the producer, a specific or narrower range of targets would be advantageous in most users’ manufacturing environments. Furthermore, with a narrow range of targets, manufacturing would benefit from using tomato paste that is consistent from container to container during the daily manufacturing process, be it a 5.2 cm. or a 6.5 cm. Bostwick specification.

Aside from individual user’s unique specifications for particular finished products, “high quality” tomato paste is considered to have high color, nutrient retention and serum viscosity (assuming “hot-break” paste), plus low mold and defect levels.

How is the level and consistency of quality achieved by the tomato paste producer?

The tomato paste manufacturing process utilized by Morning Star is shown in Exhibit 1. All manufacturers of tomato paste have similar processes; however, each is unique in the type of equipment utilized and manner in which the equipment is combined to form a “process.” A more consistent and higher level of tomato paste quality will be produced with:

1) Most critical tomato paste quality attributes are inherent in the fresh tomato. The tomato paste manufacturing process can only be designed and operated with the objective of not deteriorating the natural quality of the fresh tomato–the process can not improve quality attributes not present in the fresh tomato. Therefore, it is critical that “high quality” be present in the fresh tomato in order to obtain “high quality” in the tomato paste.

Given the importance of quality in fresh tomatoes, Morning Star purchases tomato varieties based on their potential for (a) satisfying customers’ specifications, and (b) costly effective manufacturing. These are the sole incentives Morning Star has in directing its tomato variety program. The personnel and ownership of Morning Star have their primary interests and assets focused on processing.

2) Assuming a given level of quality in the fresh tomatoes, shorter time and gentler methods of handling, from the growers’ fields to initial processing, will result in a minimum of deterioration of the fresh tomato’s quality. The standard method in the industry is to detour loads of tomatoes to a grading station somewhere between the fields and the facilities, increasing distance and delays. At Morning Star, as well as about 50% of the facilities, tomatoes are hauled directly from the fields to our facility where the weighing and grading of tomatoes takes place by State supervised inspectors, saving precious time.

When tomato loads are weighed and graded, the information is entered into our computer, and a special program operates to blend loads by assigning an unloading order for each load based on its potential viscosity and mold level. Tomatoes are unloaded in a covered shed, elevated over twenty feet above grade, and transferred by gravity between wash systems, eliminating severe handling, which is inherent in processes using elevators.

3) The specific impact the tomato paste manufacturing process has on the color and viscosity of tomato paste is in the quantity of heat units applied to the product. This is a combined function of time and temperature. Shorter holding times and lower evaporation and sterilization process temperatures (beyond the initial high temperature “hot-break” stage), result in higher quality tomato paste.

The process times and temperatures in each facility should be compared. Most new facilities have installed four-effect (utilizing steam energy input four times), four or five stage evaporators. We have installed triple-effect evaporators to accomplish ninety percent (90%) of the evaporation task and double-effect finishing evaporators for the balance. The advantages of lower temperatures, less maintenance, and higher operating efficiency with triple and double effect evaporators considerably outweigh any steam energy savings. Morning Star has steam injection sterilizing and standard flash cooling. This sterilization process is very efficient in achieving a rapid increase to sterilization temperature and an immediate decrease in temperature upon achieving sterilization in the flash cooler. Low fill temperatures arrest chemical degradation of the product once packaged.

4) Fast movement of product through the process to minimize the residence time of product at elevated temperatures is achieved by: (a) high and continuous product flow rates, plus (b) a minimum of product “tankage.” One should review facilities for simplicity of design and process, characterized by low energy and low labor input per unit of production as an indication of the amount of work required by the process. This translates into high and continuous flow rates due to fewer breakdowns and complications.

The best measure of residence time is the throughput rate relative to the total tankage in the facility. With a relatively small increase in tankage, Morning Star’s throughput rate is the highest of all facilities producing for the industrial tomato paste market.

5) A thorough blending of tomato loads from the fields and through the process is absolutely critical in the production of tomato paste that is consistent from container to container! Consistent quality ingredients are required for a using manufacturer to produce consistent quality finished products with minimal formulation changes, resulting in lower costs.

The viscosity (as well as other quality attributes), inherent in each load of fresh tomatoes, varies widely. This is due not only to the many different varieties grown, but to the irregularities within a variety resulting from variable growing conditions. From 20 to 40 different varieties are purchased by a given processor, in a given year, from over 160 commercially grown varieties in California today. Normal variation in the viscosity potential of fresh tomatoes from load to load is one to two centimeters Bostwick.

Results and Calculations:


Black Point

Reducing sugar % g.


Acidity % g. in dry matter

Salt content % g. in dry matter

1. TAT






























































Black point

Max. 2 in 1 g

Reducing sugar

Min. 40 % (w/w)


Min. 11 % puree

Min. 28 % double conc.

Min. 36 % triple conc.

Acidity %g. in dry matter

Max. 10 % of total solid

Salt content % g. in dry matter

10 % of total solid

  • Brix: was measured by refractometer.

Brix= 4, 5 * 6 = 27, 0                        (1:6 dilution factor)

  • Acidity: 10 g tomato paste + 50 g water = 60 g tomato paste solution

6, 7 ml 0,1N NaOH was spent

(10 g tomato paste * 10 ml solution) / 60 g solution = 1, 52 g tomato paste in 10 ml solution.

If 1 ml of 0, 1 N NaOH = 0, 0064 g citric acid

(0, 0064 g citric acid * 6,7 ml NaOH) / 1 ml NaOH =0,043 g citric acid

(0, 043g citric acid * 100 g tomato paste) / 1, 52 g tomato paste = 2, 83 g citric acid

(100 g in soluble solid * 2, 83 g citric acid) / 27 g soluble solid = 10, 45 % in dry matter

  • Salt content: 10 g tomato paste + 90 g ml water = 100 g tomato paste solution and 100 g tomato paste solution was completed to 500 ml.

2 ml 0,05N AgNO3 was spent

From 500 ml, 50 ml solution was taken and this solution contained 1 g tomato paste.

If 1 ml of 0,05N AgNO3 = 0, 00292 g NaCl

(0, 00292 g NaCl * 2 ml AgNO3) / 1 ml AgNO3 = 0, 00584 g NaCl

(0, 00584 g NaCl * 100 g tomato paste) / 1 g tomato paste = 0,584 % NaCl in dry matter.

(100g tomato paste * 0, 584 g NaCl) / 27 g = 2,16 g NaCl

  • Reducing Sugar: 20,3 ml of solution was spent

mg reducing sugar im 100 ml = (total reducing sugar required / liter ml) * 10

                                                = (50, 9 / 20,3) * 100

                                                = 250, 7 mg reducing sugar

(250, 7 mg reducing sugar * 100g tomato paste) / 2 g tomato paste =12,535 g reducing sugar

Note: 50, 9 was found from Lane – Eynon method page 30. 20, 3 ml titer was equal to 50, 9

  • Black point: 1 was observed black point between two glaas.


Tomato processing is seasonal, with a limited period of only 60–100 days per year. There are a very large number of different varieties of tomatoes, and the quality also depends heavily on climatic conditions and weather. For all manufacturers, the main requirement is therefore to have an efficient, reliable and versatile processing plant that is in continuous operation. Manufacturers are constantly on the lookout for any possible means to improve both quality and yield. Separation plays a major role in their ability to do this.

A wide range of products can be obtained from tomatoes, including tomato juice, paste, diced-peeled tomatoes, strained tomato pulp, sauces and powder. For the industrial market, tomato paste is probably the most important product because it is used as the basis for a wide range of other products. In general, the fruit is washed, sorted and pre-conditioned by crushing, peeling or cutting it to the required size. Depending on the particular requirements, the pre-conditioned fruit then undergoes heating, refining, pulping, reconditioning, evaporation, pasteurization and packing. Separation is a key part of the reconditioning stage of this process. By removing any moulds present, separating out the pulp and clarifying the juice, the manufacturer can control the colour, mould content and viscosity of the final product. These are the key parameters that determine quality, and thus have an influence on value further down the value chain.

In this experiment; we analyzed different labels tomato paste. These were demko, tat, öncü, penguen, home made tomato pastes.

Firstly; we measured the brix of tomato paste. Brix was measured with refractometer. Brix is important parameter for tomato paste. It shows amount of soluble solid in tomato paste. This value according to TSE, min 11 % and in double concentrated 28 %. In triple concentrated 36 %.we measured brix as 27 % and this value was appropriate TSE.

Secondly; we observed black point. Black point results from poor sorting, trimming and it is undesirable. In here; seed and skin of tomato are peeled off completely. Skin or seed exposes to heating process and burns. It appears as black point. We observed one black point in gram.

Next; we measured the salt content in tomato paste. At our analysis, we calculated 2, 16 % in dry matter. According to TSE this value is max 10 %. Our value is less than TSE value. May be during titration silver nitrate may have been added few drops. But 2, 16 can be appropriate to TSE value and analysis was true. In addition; salt gives viscosity and can increase the brix, thus salt can be used for adulteration.

Viscosity is important parameter for tomato paste, as it has a direct effect on the final product. The tomato juice from the refiner normally contains 38–45 % pulp. The aim is to produce a paste with the greatest possible level of pulp that can still be pumped effectively to the evaporator, because this reduces evaporation costs. The clear juice from the decanter centrifuge can be used to adjust the colour and viscosity of the paste until it has the required characteristics. However, it can also be used in other related production processes, such as diced and peeled tomatoes. This makes sure that nothing goes to waste, and also enables companies to diversify their product line. Each individual batch of tomatoes has its own unique characteristics.

Then; we measured the acidity of tomato paste. Acidity affects the taste of tomato paste. It was calculated 10, 45 % in dry matter. According to TSE, our result was appropriate.

Finally; we measured reducing sugar. Our result was calculated as 12, 535 % but TSE value is 40 %. That is; our result is not appropriate to TSE value. During titration making, anything was made wrong, this wrong affected our result.

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