Quality changes in high hydrostatic pressure treated enriched tomato sauce

BACKGROUND

Use of high hydrostatic pressure (HHP) with reduced processing times is gaining traction in the food industry as an alternative to conventional thermal treatment. In order to enhance functional benefits while minimizing processing losses, functionalized products are being developed with such novel techniques. In this study, changes in quality parameters for HHP treated enriched tomato sauce were evaluated, with the aim to assess its viability as an alternative to conventional thermal treatment methods.

RESULTS

HHP treatments at 500 MPa, 30 °C/50 °C significantly increased the total phenolic and lycopene content of the sauce samples, achieving 6.7% and 7.5% improvements over conventionally treated samples. The antioxidant capacity of the HHP-treated samples was also found to match or be better than conventionally treated samples. Furthermore, a T2 relaxation time study revealed that pressure-temperature processing treatments were effective in maintaining the structural integrity of water molecules. Microbiological analyses revealed that 500 MPa/50 °C 5 min treatment can offer 8 logs reduction colony formation, matching the results of conventional thermal treatment.

CONCLUSION

Combined pressure-temperature treatments improve results, reduce time consumption. 500 MPa/50 °C treatments provided retention of quality parameters and significant reduction in microbial activity. © 2024 The Author(s). Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effect of Cold- and Hot-Break Heat Treatments on the Physicochemical Characteristics of Currant Tomato (Solanum pimpinellifolium) Pulp and Paste

Currant tomato (Solanum pimpinellifolium), an underutilized wild species of modern tomato, was investigated to determine the physicochemical properties and understand the effect of cold- and hot-break heat treatments on physicochemical characteristics. Moreover, a new Arrhenius-type equation was used to model the temperature-dependent viscosity of currant tomato pulp and paste. The currant tomato’s porosity, surface area, and lycopene content were 40.96 ± 0.84%, 663.86 ± 65.09 mm2, and 9.79 ± 1.88 mg/100 g, respectively. Cold- and hot-break heat treatments had a significant (p < 0.05) effect on tomato pulp and paste color change (0.09 to 0.26; 0.19 to 1.96), viscosity (0.06 to 0.02 Pa.s; 0.85 to 0.37 Pa.s), and lycopene content (9.70 to 9.07 mg/100 g; 9.60 to 9.37 mg/100 g), respectively. An Arrhenius-type equation described the temperature-dependent viscosity of currant tomato pulp and paste with activation energy (Ea) ranging from 7.54 to 11.72 kJ/mol and 8.62 to 8.97 kJ/mol, respectively. Principal component analysis (PCA) revealed a total of variance 99.93% in tomato pulp and paste as affected by the cold- and hot-break heat treatments. Overall, the findings may provide knowledge for design graders and process optimization to develop currant tomato-based products.

Impacts of thermal and non-thermal processing on structure and functionality of pectin in fruit- and vegetable- based products: A review

Pectin, a major polysaccharide found in the cell walls of higher plants, plays major roles in determining the physical and nutritional properties of fruit- and vegetable-based products. An in-depth understanding of the effects of processing operations on pectin structure and functionality is critical for designing better products. This review, therefore, focuses on the progress made in understanding the effects of processing on pectin structure, further on pectin functionality, consequently on product properties. The effects of processing on pectin structure are highly dependent on the processing conditions. Targeted control of pectin structure by applying various processing operations could enhance textural, rheological, nutritional properties and cloud stability of products. While it seems that optimizing product quality in terms of physical properties is counteracted by optimizing the nutritional properties. Therefore, understanding plant component biosynthesis mechanisms and processing mechanisms could be a major challenge to balance among the quality indicators of processed products.

Effect of Duration and Drying Temperature on Characteristics of Dried Tomato (Lycopersicon esculentum L.) Cochoro Variety

The objective of the present study was to standardise the duration and temperatures of the conventional oven drying methods for best physical and sensory characteristics of dried tomato. The experiment consisted of two factor factorial design (3*2) with three levels of drying temperature (70°C, 80°C and 90°C) and two levels of drying duration (7 and 8 hours) with three replications. An improved and high yielding variety (Cochoro) of tomato released in 2007 for processing and widely grown in Ziwai (Maki), Ethiopia was used. Prior to drying, individual tomato fruits were washed and sliced into uniform thickness (8mm); then, the slices were placed on to the drying trays in a single layer to facilitate uniform drying in hot air oven set at predetermined temperatures per the respective treatments. Data were collected on different physical and sensory attributes and analysed using SAS software (version 9.2). The results showed that titratable acidity, total soluble solids and water absorption capacity were significantly (p≤0.001) increased due to the interaction of degree of temperature and duration of oven drying. In contrast, pH and water activity decreased as the drying temperature and duration increased. Drying at 70°C for 7 hours produced dried tomatoes with the highest sensorial acceptability and physical attributes while higher temperatures (80, 90°C) and longer duration (9 hours) significantly detract the quality of dried tomato. Hence, it is possible to add value and preserve tomatoes through oven drying at the right temperature and optimum duration.

Effect of Temperature, Time, and Material Thickness on the Dehydration Process of Tomato

This study aimed to evaluate the effects of temperature, time, and thickness of tomatoes fruits during adiabatic drying process. Dehydration, a simple and inexpensive process compared to other conservation methods, is widely used in the food industry in order to ensure a long shelf life for the product due to the low water activity. This study aimed to obtain the best processing conditions to avoid losses and keep product quality. Factorial design and surface response methodology were applied to fit predictive mathematical models. In the dehydration of tomatoes through the adiabatic process, temperature, time, and sample thickness, which greatly contribute to the physicochemical and sensory characteristics of the final product, were evaluated. The optimum drying conditions were 60°C with the lowest thickness level and shorter time.

Combined pressure-temperature effects on carotenoid retention and bioaccessibility in tomato juice

This study highlights the changes in lycopene and β-carotene retention in tomato juice subjected to combined pressure-temperature (P-T) treatments ((high-pressure processing (HPP; 500-700 MPa, 30 °C), pressure-assisted thermal processing (PATP; 500-700 MPa, 100 °C), and thermal processing (TP; 0.1 MPa, 100 °C)) for up to 10 min. Processing treatments utilized raw (untreated) and hot break (∼93 °C, 60 s) tomato juice as controls. Changes in bioaccessibility of these carotenoids as a result of processing were also studied. Microscopy was applied to better understand processing-induced microscopic changes. TP did not alter the lycopene content of the tomato juice. HPP and PATP treatments resulted in up to 12% increases in lycopene extractability. all-trans-β-Carotene showed significant degradation (p < 0.05) as a function of pressure, temperature, and time. Its retention in processed samples varied between 60 and 95% of levels originally present in the control. Regardless of the processing conditions used, <0.5% lycopene appeared in the form of micelles (<0.5% bioaccessibility). Electron microscopy images showed more prominent lycopene crystals in HPP and PATP processed juice than in thermally processed juice. However, lycopene crystals did appear to be enveloped regardless of the processing conditions used. The processed juice (HPP, PATP, TP) showed significantly higher (p < 0.05) all-trans-β-carotene micellarization as compared to the raw unprocessed juice (control). Interestingly, hot break juice subjected to combined P-T treatments showed 15-30% more all-trans-β-carotene micellarization than the raw juice subjected to combined P-T treatments. This study demonstrates that combined pressure-heat treatments increase lycopene extractability. However, the in vitro bioaccessibility of carotenoids was not significantly different among the treatments (TP, PATP, HPP) investigated.

Effect of mechanical and thermal treatments on the microstructure and rheological properties of carrot, broccoli and tomato dispersions

BACKGROUND

The food industry has shown an increased interest in the manufacture of healthier and more natural food products. By tailored processing fruit and vegetables can be used as structurants thus reducing artificial gums and stabilisers. The effect of different thermal and mechanical treatments, including high-pressure homogenisation, on the microstructural and rheological properties of carrot, broccoli and tomato dispersions was studied. As part of the rheological characterisation small oscillatory deformation as well as shear flow measurements were performed.

RESULTS

Carrot and broccoli showed a different behaviour from tomato under the conditions studied. Changing the order of thermal and mechanical treatment led to microstructures with different flow properties. The resulting microstructures differed in the manner of cell wall separation: either breaking across the cell walls or through the middle lamella. High-pressure homogenisation decreased the viscosity of carrot and broccoli dispersions, while it increased the viscosity of tomato. Cryo-scanning electron microscopy showed that the cell walls of carrot and broccoli remained as compact structures after homogenisation whereas tomato cell walls were considerably swollen.

CONCLUSIONS

Based on the type of vegetable, the different processes applied led to microstructures with different rheological properties. This study shows that particle size distribution, morphology and phase volume are important parameters to explain the complex relationship between rheology and microstructure for these types of systems.