Encarna Aguayo

Bioactive compounds from flesh and by-product of fresh-cut watermelon cultivars.

BACKGROUND The fresh-cut industry produces thousands of tons of waste in non-edible portions that present an environmental and management problem. These by-products could be reused, in particular, to obtain bioactive compounds. In this study, five different fresh-cut watermelon cultivars were assessed for their flesh and by-product bioactive contents. RESULTS The amount of by-product varied between 31.27 and 40.61% of initial fresh weight (f.w.) depending on the cultivar. Watermelon cultivars were poor sources of total antioxidant, and the content was similar between rind and flesh samples (46.96 vs 43.46 mg ascorbic acid equivalent antioxidant capacity kg(-1) f.w.). However, the rind had a moderate total phenolic content higher than that of the flesh (458 vs 389 mg chlorogenic acid equivalent kg(-1) f.w.) and a much higher content of the amino acid citrulline (3.34 vs 2.33 g kg(-1) f.w.), which has potential bioactive properties. CONCLUSION Watermelon rind offers quantitative interest as a natural source of citrulline, particularly Fashion, a dark-skinned, seedless cultivar. More research is required on the efficient extraction of citrulline from watermelon rind and its suitability as an additive to drinks, juices or others products to produce new functional food products with valid health claims.

Watermelon Juice: Potential Functional Drink for Sore Muscle Relief in Athletes

l-Citrulline is an excellent candidate to reduce muscle soreness, and watermelon is a fruit rich in this amino acid. This study investigated the potential of watermelon juice as a functional drink for athletes. An in vitro study of intestinal absorption of l-citrulline in Caco-2 cells was performed using unpasteurized (NW), pasteurized (80 °C for 40 s) watermelon juice (PW) and, as control, a standard of l-citrulline. l-citrulline bioavailability was greater when it was contained in a matrix of watermelon and when no heat treatment was applied. In the in vivo experiment (maximum effort test in a cycloergometer), seven athletes were supplied with 500 mL of natural watermelon juice (1.17 g of l-citrulline), enriched watermelon juice (4.83 g of l-citrulline plus 1.17 g from watermelon), and placebo. Both watermelon juices helped to reduce the recovery heart rate and muscle soreness after 24 h.

Effect of storage time and temperature on the physicochemical and sensory characteristics of commercial apricot jam

Storage conditions are important factors for jam quality. The objective of this study was to monitor the physicochemical stability and sensorial profile of apricot jam during storage for 60 days at 5 °C, 25 °C and 37 °C. For that purpose, special attention was paid to total soluble solids (TSS), titratable acidity (TA), colour, free amino acids (FAA), total sugars (TS) and hydroxymethylfurfural (HMF). The decreasing parameter for jam at the end of storage under 5 °C, 25 °C and 37 °C, respectively, were 16.81%, 34.30% and 56.01% for FAA, and 5.52%, 9.02% and 7.46% for TS; likewise, the increasing were 19.81%, 22.94% and 25.07% for TA, 3.15%, 4.08% and 4.47% for TSS, 15.96%, 112.76% and 150% for HMF. Jam stability was better at 5 °C than 25 °C and 37 °C. The interaction time-temperature factor had significant effects on pH, TS, FAA and HMF, unlike TA, TSS and sensorial profile.

Impact of packaging atmosphere, storage and processing conditions on the generation of phytoprostanes as quality processing compounds in almond kernels.

The thermal processing of almond kernels implies the use of techniques that produce chemical changes such as oxidation. Phytoprostanes (PhytoPs) are considered biomarkers of the oxidative stress in plants. We studied the PhytoP profile in kernels of almond cultivars under different conditions, in relation to packaging, temperature and time of storage and processing. The most abundant PhytoP was the F1t series. The PhytoP levels increased significantly with the time of storage (3 and 6months) and the total PhytoP concentration was higher under air than in a vacuum packaging atmosphere. Storage at 24°C raised the concentrations of individual PhytoPs and the total sum of PhytoPs. The frying and roasting processes led to a strong reduction of the original concentration of most PhytoPs and promoted the synthesis of specific PhytoPs that were not detected in raw kernels and thus could be biomarkers of the degree of oxidative degradation of almonds.

Phytoprostanes in almonds: identification, quantification, and impact of cultivar and type of cultivation

Recently, the relationship between oxidative stress and the phytoprostanes content in plants has been studied. In 1998, it was discovered that phytoprostanes are generated from α-linolenic acid, following a non-enzymatic pathway initiated by enhanced formation of free radicals. Almonds and other nuts have favorable contents of polyunsaturated fatty acids; one of the most-polyunsaturated fatty acids present in plants is α-linolenic acid. This study represents a first approach to the quantitative and qualitative determination of the phytoprostanes profile in 11 almond cultivars under different agronomic conditions (conventional versus ecological, rain-fed versus irrigated). In the kernels have been identified 9-F1t-phytoprostane, 9-epi-9-F1t-phytoprostane, ent-16-epi-16-F1t-phytoprostane, ent-16-F1t-phytoprostane, 9-D1t-phytoprostane, 9-epi-9-D1t-phytoprostane, 16-B1-phytoprostane, and 9-L1-phytoprostane. The total phytoprostane content was in the range of 4.0 to 23.8 ng per 100 g. F1-phytoprostanes predominated and were identified in all almond cultivars. L1-phytoprostanes were minor components while D1-phytoprostanes were only detected in cultivars ‘Colorada’ and ‘Avellanera’. The phytoprostane profile varied greatly depending on the genotype, but was also affected by factors such as the agricultural system (conventional or ecological) and irrigation. The ecological system promoted the synthesis of D1-phytoprostanes. Almonds from rain-fed trees had lower individual and total phytoprostane concentrations than those under irrigation, even though non-irrigation led to the detection of the 16-F1-phytoprostanes. Consequently, irrigation and ecological techniques applied to almonds could be considered as actions to enhance their phytoprostane content and hence their potential beneficial effects on human health.

Quality of tomato slices disinfected with ozonated water

Fresh-cut industry needs novel disinfectant to replace the use of chlorine. Ozone is one of the most powerful oxidizing agents and is applied in gaseous or aqueous form for sanitation purposes. However, the strong oxidative effect could affect the nutritional and sensorial quality, in particular, when time of washing is extended. For that reason, the overall impact of ozonated water (0.4 mg/L) dipping applied during 1, 3 and 5 min compared to control washed in water during 5 min was studied in tomato slices stored during 14 days at 5 ℃. According to the results, ozonated water treatment of 3 min achieved the best firmness retention, microbial quality (mesophilic, psychrotrophic and yeas load) and reduced the consumption of fructose and glucose. The use of ozonated water did not affect the total acidity, pH, total solid soluble, organic acid as ascorbic, fumaric or succinic acid and the sensorial parameters, which were only affected by storage time. However, the poor appearance, aroma and overall quality obtained in all treatments prevented shelf life of 14 days and the quality at acceptable levels was established in 10 days at 5 ℃. It is recommended to wash tomato slices with 0.4 mg/L ozonated water for 3 min only. Extending treatment duration did not improve the microbiological quality, possibly due to the extra time permitting the ozone to react with other components of the fruit tissue, undermining the antimicrobial benefits.

Quality changes of fresh-cut pomegranate arils during shelf life as affected by deficit irrigation and postharvest vapour treatments

BACKGROUND The effect of two sustained deficit irrigation (SDI) strategies, compared to a control, on postharvest physicochemical, microbial, sensory quality attributes and anthocyanin content of fresh-cut pomegranates arils throughout 18 days at 5 °C was studied. Furthermore, the effect of vapour treatments (4, 7 and 10 s) compared to a conventional sanitizing treatment with NaClO on such quality parameters in combination with the preharvest treatments was also studied. RESULTS According to sensory analyses, the shelf life of arils from control and SDI-irrigated fruit was established in 14 and 18 days at 5 °C, respectively, showing 4 and 7 s vapour treatment time the best sensory quality. No significant change was observed in physicochemical quality attributes, across all treatments during storage, while low microbial loads were registered (<3 log CFU g(-1)) after shelf life. Postharvest treatments that had least effect on anthocyanin content on processing day were 7 and 10 s. CONCLUSION Vapour treatments of 7-10 s applied to pomegranate arils led to an extended shelf life up to 18 days at 5 °C with better results in SDI-irrigated samples with a water saving of 6-11%.

Influence of acidification, pasteurization, centrifugation and storage time and temperature on watermelon juice quality

BACKGROUND Watermelon juice has gained increasing popularity among consumers as a rich natural source of functional compounds such as lycopene and citrulline. However, the final quality of the juice depends significantly on its acidification, pasteurization, centrifugation and storage time and temperature. In this study, these characteristics were assessed in watermelon juice pasteurized at 87.7 °C for 20 s and stored for up to 30 days at 4 or 8 °C. RESULTS The acidifier citric acid provided an adequate sensory quality, similar to natural watermelon juice. Centrifugation and pasteurization significantly reduced the red color, bioactive compounds (lycopene, antioxidant capacity and total polyphenols) and sensory quality of the juice, particularly when the storage time was extended and a temperature of 8 °C was used (P ≤ 0.05). All treated juices were microbiologically safe for up to 30 days when stored at 4 or 8 °C. In terms of sensory acceptability, only non-centrifuged juices stored for up to 20 days at 4 °C remained above the commercial limit. CONCLUSION The present results suggest that using a non-centrifugation process and a storage temperature of 4 °C yields a watermelon juice that better retains its sensory and functional qualities.

The suitability of three Galia melon cultivars and different types of cuts for the fresh-cut industry

BACKGROUND Melons (Cucumis melo L.) are widely cultivated in Mediterranean countries. For fresh-cut melon elaboration, factors such as type of cultivar and cut have a significant impact on final product quality. The quality parameters from long, medium and short shelf-life Galia melon cultivars, cut into different shapes such as slices, trapezoids and cylinders and stored up to 10 days at 5 °C, were evaluated in order to learn the suitability of these cultivars and type of cut for minimal processing. RESULTS In general, long-life melon cultivar had a low respiration rate and ethylene emissions, and high tissue firmness, but low levels of glucose, fructose, vitamin C and flavor rating by consumers. However, despite having higher metabolic activity and susceptibility to microbial spoilage, the short shelf-life cultivar melon had higher firmness retention. This cultivar was characterized by its richness in glucose, fructose and vitamin C, and its sensory quality (flavor) was highly valued. In general, the medium cultivar had an intermediate behavior between long and short cultivars but without their positive attributes. As a consequence of the most intense damage, the cylindrical shape had higher metabolic activity, susceptibility to microbial spoilage and reduced appearance. CONCLUSIONS In the long and medium-life cultivars studied, low flavor was the limiting factor to extend the shelf-life of fresh-cut melon while for the short-life cultivar the limiting factor was its susceptibility to bacterial growth. Cut types such as cylinders should be avoided.

Continuous microwave pasteurization of a vegetable smoothie improves its physical quality and hinders detrimental enzyme activity.

The effect of a pasteurization treatment at 90 ± 2 ℃ for 35 s provided by continuous microwave under different doses (low power/long time and high power/short time) or conventional pasteurization on the quality of orange-colored smoothies and their changes throughout 45 days of storage at 5 ℃ was investigated. A better color retention of the microwave pasteurization- treated smoothie using high power/short time than in conventionally processed sample was evidenced by the stability of the hue angle. The continuous microwave heating increased the viscosity of the smoothie more than the conventional pasteurization in comparison with non-treated samples. Lower residual enzyme activities from peroxidase, pectin methylesterase and polygalacturonase were obtained under microwave heating, specifically due to the use of higher power/shorter time. For this kind of smoothie, polygalacturonase was the more thermo-resistant enzyme and could be used as an indicator of pasteurization efficiency. The use of a continuous semi-industrial microwave using higher power and shorter time, such as 1600 W/206 s and 3600 W/93 s, resulted in better quality smoothies and greater enzyme reduction than conventional thermal treatment.