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Research Article The present work aimed to evaluate, through thermal degradation kinetics (80 °C to 98 °C in time intervals of 0.5 to 25 min), the effects of different thermal treatments on the biochemical, physicochemical, sensory and microbiological parameters of two mixed fruit and vegetable pulps, a yellow and a red one. The evaluated fruit and vegetable pulps resulted from the mixture of different fruits and vegetables proportions (pineapple, beetroot, strawberry and lemon juice) added to a 50% (p/p) pear-based pulp to maximize their bioactivity, physicochemical stability and sensorial acceptance. Evaluated quality parameters included the determination of peroxidase activity (POD), pH, soluble solids content (SSC), total phenolic content (TPC), CIELab colour, sensory evaluation (colour, taste and aroma) and total mesophilic aerobic counts (TAPC). Regarding heat treatments optimization for both pulps with lower pH, it was concluded that higher temperature treatments (90 to 98 °C) applied over a shorter time (less than 5 min) were more effective to inactivate POD, to reduce the initial microbial load (>2 log10 cycles) and to maximize sensorial attributes. In both mix pulps, total phenolic content (TPC) was not significantly influenced by the different applied time-temperature binomials. From the degradation kinetic models and as an example, it was possible to conclude that POD followed a 1st order kinetic, where the temperature effect was well fitted to the Arrhenius equation. The results allowed to obtain optimized time-temperature binomials for each pulp to simultaneously achieve POD enzyme inactivation, microbial reduction, and maximization of quality parameters relatively to fresh pulps, 90 °C/5 min and 98 °C/2.5 min, for the yellow pulp and red pulp, respectively info:eu-repo/semantics/publishedVersion

Tomatoes are a popular and rich fruit due to their nutritional and bioactive composition as vitamins, antioxidants, and phenolics contributing to the promotion of consumer health. For this reason, emerging postharvest technologies need to be evaluated to achieve the maintenance of sensorial and quality-related characteristics, like color and texture, while aiding to fruit decontamination. Optimization of thermosonication as postharvest treatments on whole, mature-green tomatoes (cv. &ldquo, Zinac&rdquo, ) to improve quality (color, texture, total phenolic content, and weight loss) was performed by response surface methodology. Temperature (32&ndash, 48 &deg, C), treatment time (13&ndash, 47 min), and storage period at 10 &deg, C (1&ndash, 15 days) at constant ultrasound frequency (45 kHz, 80% power level), were the independent variables. In general, thermosonication delayed tomato color changes while achieving total phenolic content increase and good overall quality. Three optimal thermosonication conditions were selected and validated (32 &deg, C-13 min, 35 &deg, C-20 min and 40 &deg, C-30 min). The most suitable thermosonication condition that promoted a longer storage while keeping a high-quality standard was at 40 &deg, C during 30 min. This study demonstrated that thermosonication provides an effective alternative methodology to guarantee tomato quality without significant change during the expected postharvest period.

Whole tomato fruits were treated at ultrasonic power levels from 10% to 100%, and at a constant frequency of 45 kHz, for different times (1-19 min). A central composite rotatable design (CCRD) was applied to optimise ultrasonic treatments for tomato quality (colour, texture and total phenolic content (TPC)) maintenance. According to response surface analysis, the optimal treatment parameters were 55%_10 min, 80%_15 min and 100%_19 min. At these conditions, and especially at higher power levels, a maximum retention of colour and texture, as well as an increase of TPC and microbial reduction were obtained in comparison with untreated fruits during 15 storage days at 10 degrees C. The ultrasounds treatment was found to be effective in delaying colour development and texture losses, preserving sensorial quality of whole tomato, with increase of TPC and microbial load reduction. Moreover, this postharvest treatment can be used as an alternative for extending fresh fruits shelf-life.

This study evaluated the effect of water heat treatment (WHT, immersion in a water bath at 40C - 30 min) application in alternative to the conventional decontamination treatment of chlorinated water (150 ppm at 5C, pH 6.5 during 2 min) on tomato (cv. Zinac) at two maturity stages (turning and pink). Physiochemical attributes, enzymatic activities and microbial load were evaluated after treatments and during 14 days of storage at 10C. The WHT applied was very effective on microbial reduction and delayed physiochemical changes of tomato, namely firmness loss and red color development during storage period, especially at turning maturity stage. Based on the firmness parameter, shelf-life of control and WHT samples were determined. Our results provide strong evidence that postharvest WHT (40C - 30 min) for tomato fruits at turning maturity stage guarantees the overall quality at 10C twice as long of fruits washed with chlorinated water.

Submitted by Anabela Morais (ajmorais@porto.ucp.pt) on 2013-01-25T15:03:59Z No. of bitstreams: 1 AN4.pdf: 13241459 bytes, checksum: f19305ff1f5e18bb91c4bf05c1e53e56 (MD5) Approved for entry into archive by Maria João Pinto (mjpinto@porto.ucp.pt) on 2013-01-28T10:20:49Z (GMT) No. of bitstreams: 1 AN4.pdf: 13241459 bytes, checksum: f19305ff1f5e18bb91c4bf05c1e53e56 (MD5) Made available in DSpace on 2013-01-28T10:20:49Z (GMT). No. of bitstreams: 1 AN4.pdf: 13241459 bytes, checksum: f19305ff1f5e18bb91c4bf05c1e53e56 (MD5) Previous issue date: 2012 info:eu-repo/semantics/publishedVersion

Available at Sciverse ScienceDirect Abiotic stresses such as heat shock and UV-C irradiation can be used to induce synthesis of bioactive compounds and to prevent decay in fresh-cut fruits and vegetables. This study aimed to evaluate the effects of heat shock and UV-C radiation stress treatments, applied in whole carrots, on the overall quality of fresh-cut carrot cv. Nantes during storage (5 C). Heat shock (HS, 100 C/45 s) and UV-C (0.78 0.36 kJ/m2) treated samples had higher phenolic content and exhibited reduced POD activities during storage when compared to control (Ctr) samples (200 mg/L free chlorine/1 min). All samples showed reduced carotenoid content considering raw material. Nonetheless, UV samples registered a three-fold increase in carotenoid content in subsequent storage. Fresh-cut carrot colour showed a continuous increase in whiteness index (WI) values during storage regardless of treatment without impairing visual quality. Respiratory metabolism was affected by both abiotic stress treatments since reduced O2/CO2 rates were found, more significant in HS samples. The decontamination effect was more expressive in HS samples, where a 2.5 Log10 cfu/g reduction in initial microbial load and reduced microbial growth were achieved

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Proceedings of the International Conference “Environmentally friendly and safe technologies for quality of fruit and vegetables”, held in Universidade do Algarve, Faro, Portugal, on January 14-16, 2009. This Conference was a join activity with COST Action 924. Quality and safety attributes, like colour (CIELab parameters), texture (Maximum force – MF), total phenolics content (TPC), peroxidase activity (POD), microbial count and moulds & yeasts (Log10 cfu g-1) were determined on heat treated mature-green tomatoes at temperature ranging of 40 to 50 ºC and different times. Heat treatments (HT) did not affect significantly (p>0.05) the tomatoes colour. In terms of texture, a reduction of 10% MF was observed at 50 ºC_15min...

The effect of temperature and storage time on tomatoes (Lycopersicum esculentum L.) colour (a* and ºh) and firmness (maximum force) were analysed at 2º, 5º, 10º, 15º and 20 ºC. The development of these quality attributes followed a fractional kinetic model. The regression coefficient (R2) for the generated models were high, 0.94 for both colour parameters (a* and ºh) and 0.84 for firmness. A significant (p