Influence of a heat-shock pre-treatment on wound-induced phenolic biosynthesis as an alternative strategy towards fresh-cut carrot processing

In fresh-cut vegetables, plant tissues are often challenged by (a)biotic stresses that act in combination, and the response to combinatorial stresses differs from that triggered by each individually. Phenolic induction by wounding is a known response contributing to increase products phenolic content. Heat application is a promising treatment in minimal processing, and its interference on the wound-induced response is produce-dependent. In carrot, two-combined stress effects were evaluated: peel removal vs. shredding, and heat application (100 C/45 s) vs. shredding, on changes in total phenolic content (TPC) during 10 days (5 C). By applying the first stress combination, a decrease in TPC was verified on day 0 ( 50%), ascribed to the high phenolic content of peels. Recovery of initial fresh carrot levels was achieved after 7 days owing to phenolic biosynthesis induced by shredding. For the second combination, changes in TPC, phenylalanine-ammonia-lyase (PAL), and peroxidase (POD) activity of untreated (Ctr) and heat-treated (HS) peeled shredded carrot samples were evaluated during 10 days. The heat-shock did not suppress phenolic biosynthesis promoted by PAL, although there was a two-day delay in TPC increments. Notwithstanding, phenolic accumulation after 10 days exceeded raw material TPC content. Also, the decrease in POD activity (30%) could influence quality degradation during storageinfo:eu-repo/semantics/publishedVersio

Multi-Target Alternative Approaches to Promoting Fresh-Cut Carrots’ Bioactive and Fresh-like Quality

Fresh-cut fruits and vegetables, as near-fresh foods, are a quick and easy solution to a healthy and balanced diet. The rapid degradation of nutritional and sensory quality during the processing and storage of a product is critical and plant-type-dependent. The introduction of disruptive technological solutions in fresh-cut processing, which could maintain fresh-like quality with less environmental impact, is an emerging research concept. The application of abiotic stress treatments (heat shock and UV-C) induces metabolic responses and microbial effects in plant tissues, potentially slowing down several quality senescence pathways. The previously selected combined and single effects of heat shock (100 °C/45 s; in the whole root) and UV-C (2.5 kJ/m2) treatments and two packaging conditions (oriented polypropylene (OPP) vs. micro-perforated OPP films) on controlling critical degradation pathways of fresh-cut carrots and on promoting bioactive and sensory quality during storage (5 °C, 14 days) were studied. Among the tested combinations, synergistic effects on the quality retention of fresh-cut carrots were only attained for applying heat shock associated with micro-perforated OPP film packaging. Its effects on reducing (3.3 Log10 CFU/g) the initial contamination and controlling microbiological spoilage (counts below the threshold limit of 7.5 Log10 CFU/g), increasing the bioactive content (38% and 72% in total phenolic content and chlorogenic acid, respectively), and preserving fresh quality attributes prove to be a viable alternative technology for shredded carrot processing.info:eu-repo/semantics/publishedVersio

Influence of postharvest ultrasounds treatments on tomato (Solanum lycopersicum, cv. Zinac) quality and microbial load during storage

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.info:eu-repo/semantics/publishedVersio

Modelling colour and firmness changes of stored tomatoes (Lycopersicum esculentum L.) at different conditions

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<0.05) increase and decrease for a* and maximum force, respectively, were observed during storage. This study can contribute for the understanding of the real effect of temperature and storage time on two important quality attributes of tomatoes, such as colour and firmness

Seed origin drives differences in survival and growth traits of cork oak (Quercus suber L.) populations

Cork oak (Quercus suber L.) has a high ecological and social value and supplies raw materials for the cork industry, a relevant contributor to the economies of Mediterranean countries. Understanding the adaptation potential of cork oak populations to cope with different environmental conditions is a key issue of forest management, particularly for selecting the most adapted genetic material for (re)forestation and assuring the long-term sustainability of the cork industry. Intraspecific variation in fitness surrogate traits (survival, height and stem diameter) was investigated in thirty-five cork oak populations sampled from the entire range of the natural distribution of the species. The study was conducted in two provenance field trials, established in Portugal under different edaphoclimatic conditions. Each trial was surveyed at four tree ages (two ages, 11 and 14 years, were sampled simultaneously in both trials). The trial located at a lower altitude, which had higher mean winter and annual temperatures, exhibited higher growth and survival rates. In both trials, significant genetic variation among cork oak populations was observed for the analyzed traits and evaluated ages. Moroccan populations displayed a higher probability of survival and higher growth rates, while local populations exhibited an intermediate performance. Low to moderate correlations were found between the analyzed traits and the environmental variables of seed origin, suggesting that factors other than climate are likely to be relevant for cork oak adaptation. Moderate to high values of population mean-basis broad-sense heritability (H2≥0.44) and high genetic correlations between traits (0.88–0.95) were found for growth traits. This information is crucial for the establishment of a breeding program for the species. With this study, we have improved the knowledge regarding how cork oak performs for fitness surrogate traits in different environments.The cork oak provenance field trials were funded by European (FAIR1-CT-95-0202) and national foundations (PBIC/AGR/2282/95, PAMAF 4027, PRAXIS/3/3.2/Flor/2110/95). The growth and survival measurements were assessed with the support of the European project: “CREOAK: Conservation and restoration of European cork OAK woodlands: a unique ecosystem in the balance” (QLK5–CT–2002–01594); and the “Repovoamento com sobreiro: Variabilidade genética e biologia da semente conservada (POCTI/41359/AGG/2001) national project. Research activities were also funded by Forest Research Centre (CEF), a research unit funded by Fundação para a Ciência e a Tecnologia I.P. (FCT), Portugal (UID/AGR/00239/2013). Teresa Sampaio was funded by the Portuguese Foundation for Science and Technology, Portugal through a doctoral grant under the SUSFOR Doctoral Programme (PD/ BD/52402/2013). The authors are thankful to Maria Carolina Varela who setting up the EU-concerted action on cork oak, FAIR I CT 95 0202 and to Carla Faria, Carla Leite and Regina Chambel that collaborated on the establishment of the Portuguese genetic trials. We also thanks to Ana Margarida Nunes, Lurdes Marçal, Madalena Silva, Maria João Lourenço and Sara Rocha for their support in field work.info:eu-repo/semantics/publishedVersio

Quality changes during thermal processing of two mixed formulas of fruits and vegetables pulps

Research ArticleThe 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, respectivelyinfo:eu-repo/semantics/publishedVersio

Effect of heat treatment on smoothie quality by response surface methodology

Smoothies are a popular and convenient way for to consume bioactive compounds from fruits and vegetables such as total phenolics, carotenoids and flavonoids, with the preservation treatment being an important action to guarantee the safety and extension of shelf-life. The main goal of this study was to evaluate the impact of heat treatment (HT) on smoothie prepared with “Fuji “apple (41%), pineapple (31%), cabbage (8%), pumpkin (10%) and banana (10%), by response surface methodology (RSM), where the temperature (70–100 °C) and treatment time (0.5–10.5 min), were the dependent variables. After optimization of HT conditions, a validation assay was performed to guarantee the minimal changes on color and reduction of 90% of polyphenoloxidase enzyme (PPO). Antioxidant activity (Ferric reducing antioxidant power assay (FRAP), DPPH, ABTS), total phenolics content (TPC), pH and solids soluble content were also analyzed. Predicted models of color parameters (L*, a*, ºh) and PPO enzymatic activity were found to be significant (p < 0.05) with regression coefficients (R2) of 0.84, 0.86, 0.92 and 0.97, respectively. From the RSM-generated model, the HT conditions that ensure a minimal green loss of smoothie and inactivation of PPO enzyme was at 85 °C over 7 min. In the validation study, these conditions were tested and proved to be sufficient to achieve the main goals. In the heat-treated smoothie, increases in TPC (10%) and antioxidant capacity (ABTS: 50%, DPPH: 17%, FRAP: 13%) were attained. This study demonstrated that RSM was efficient to select the optimal conditions of HT and improve the important quality properties that influence the product quality and the potential consumer’s health (TPC and antioxidant capacity).info:eu-repo/semantics/publishedVersio