Commercial Tomato Paste Research Articles

Comprehensive exergy analysis of a commercial tomato paste plant with a double-effect evaporator

In this study, a detailed exergy evaluation of a commercial tomato paste plant with a double-effect evaporator was conducted in order to provide information on the system thermodynamic inefficiencies. Using energy and exergy balance equations, all components of the plant were analyzed individually and their exergetic parameters were calculated on the basis of actual operational data. The required data were obtained from Nazchin tomato paste factory located in Tehran, Iran. In addition, it was attempted to quantify the exergy utilized for processing a given amount of the tomato paste. The results showed that over 82% of the total destroyed exergy in the plant occurred in the boiler combination as the main component wasting exergy. Furthermore, exergy analysis introduced this combination as the main equipment rejecting exergy to the ambient where 4.79% of its total exergy input was lost. The rational exergy efficiency of the first- and second-effect evaporative units was found to be 65.33% and 56.60%, respectively. The specific exergy consumption of the tomato paste production was also determined as 16.83 MJ/kg. Generally, exergy concept and its extensions could be served as a powerful assessment technique to optimize the design and performance of multiple-effect evaporation systems employed in food industry.

Changes in Antioxidant and Metabolite Profiles during Production of Tomato Paste

Tomato products and especially concentrated tomato paste are important sources of antioxidants in the Mediterranean diet. Tomato fruit contain well-known antioxidants such as vitamin C, carotenoids, flavonoids, and hydroxycinnamic acids. The industrial processing of this fruit into tomato paste involves several treatments that potentially affect the final profile of antioxidants and other metabolites in the commercial product. Here we have used both biochemical and metabolomic techniques to assess the effect of each separate step in the industrial production chain starting from fresh fruit to the final tomato paste. Material was collected from five independent tomato paste production events spread over two successive years. Samples comprised the intact ripe fruits and semifinished products after fruit-breaking, separation of the pulp from skin and seeds, evaporation, and finally after canning and pasteurization. The effect of each processing step was determined by different types of analysis. First, the total antioxidant capacity and total phenolic content were determined by commonly used spectrophotometric methods. Second, individual antioxidants in the extracts were identified and compared using an HPLC with online antioxidant detection. Third, in each sample the levels of the major individual antioxidants present, i.e., vitamin C, phenolic compounds (such as rutin and chlorogenic acid), tocopherols, and carotenoids, were quantified. Fourth, an untargeted metabolomic approach using LC-QTOF-MS was used to identify those production steps that have the largest impact on the overall metabolic profile in the final paste as compared to the original fruits. This multifaceted approach has revealed that each processing step induces specific alterations in the metabolic profile, as determined by the different analysis procedures, and that in particular the fruit-breaking step and the removal of seed and skin significantly affect the levels of antioxidants and many other metabolites present in commercial tomato paste.

Isolation of lycopene from crude tomato extract via selective inclusion in deoxycholic acid

Deoxycholic acid has been used as host in the separation of C-40 carotenoid isomers. The methodology was successfully applied to recover almost pure lycopene from commercial tomato paste.

Squeezing flow of semi liquid foods between parallel Teflon coated plates

Samples of commercial tomato paste, low fat mayonnaise and mustard about 6–8 mm thick were squeezed to 0.8 mm at various speeds between 5 mm min−1 and 25 mm min−1 between Teflon-coated parallel plates 127 mm in diameter using an Instron UTM Model 5542. All the log force vs log height relationships had a clearly identified linear region. This indicated that a dominant squeezing flow regime was achieved at about 3 mm height, and that the machine has the proper stiffness to perform the tests. The stress level at a pre-selected height in this region is a measure of consistency, sensitive enough to distinguish between products of different brands. The residual stress after relaxation for about 2 min was on order of 10–50% of the initial stress, an indication that all three foods have a considerable structural integrity. In all three products there was a considerable discrepancy between the observed rate effects and predictions based on a pseudoplastic (power law) model. It could be described by the empirical relation (Fv1 − FR)/(Fv2 − FR)=(V1/V2)m where Fv1 and Fv2 are the forces at the given displacement reached at speeds v1 and v2 respectively, FR is the residual force after relaxation (found to be practically rate independent), and m is a constant of the order of 0.15–0.33, independent of the compression velocities ratio but characteristic of the food and brand. The calculated elongational viscosity was not a unique function of biaxial strain rate. To a certain extent, this was probably due to imperfect lubrication. But it was also a manifestation of these products considerable structural integrity which cannot be accounted for by models developed for ideal liquids.

IMPERFECT SQUEEZING FLOW VISCOSIMETRY OF SELECTED TOMATO PRODUCTS1

ABSTRACTThe rheological properties of different brands of commercial tomato paste, sauce, puree and ketchup were estimated by imperfect squeezing flow viscosimetry using a wide plate and a shallow container. The tests were performed with polished and grooved surfaces. In both, slip was prominent to such an extent that the equations for lubricated squeezing flow had to be used for the calculation of rheological parameters. Despite its crudeness, the procedure was sensitive enough to consistently monitor rheological differences between commercial products of different brands in terms of the apparent stress at a given specimen height, the consistency, K, and flow index, n, of the pseudoplastic liquid constitutive equation, and the apparent biaxial elongational viscosity, μb and its strain rate dependency. In tomato paste, the flow behavior index was approximately the same in all the brands (n ∼ 0.5), and the values of K and μb had a linear relationship. Residual forces after relaxation provided an additional textural measure related to the yield stress. Differences between products of different brands could be consistently monitored regardless of whether the test was performed at a fixed specimen height or a preset initial force.

Masking of Soy Protein Flavor by Tomato Sauce

ABSTRACTFlavor interaction in a model system consisting of 5% (w/w) soy protein in a series of tomato sauces containing 55–100% commercial tomato paste was evaluated by six trained panelists. Intensities of the tomato flavors were found to increase with tomato concentration. The combination of the soy and tomato components resulted in the repression of the bitter, harsh and astringent tomato flavors, and significantly reduced the overall flavor and acidic intensities of the tomato component. Individual odors and flavors of the soy protein became indistinguishable in soy/tomato mixtures. There was a substantial reduction in the overall soy odor, flavor and aftertaste with the increase in tomato concentration.

Characterization and Drying of Tomato Paste Foam by Hot Air and Microwave Energy

The formulation of stable tomato paste foams and the effect of characteristics such as foam thickness, density and bubble size on the drying rates utilizing hot air and microwave energy were investigated.Air injected foams were produced from commercial tomato paste (27% solids) and mono and diglyceride stabilizer. The foams were dried by hot air (76.7°C) or by microwave energy at a frequency of 2450MHz at various power levels.Excellent drying characteristics were obtained for foams of a density of 0.38g/cm3 and corresponding bubble size index of about 83μm and containing 1% stabilizer. Both hot air and microwave energy dehydration yielded quality products, but the dehydration rates were much greater for the microwave power method (approx. 4 to 8 times, depending upon the power level used).