Begoña de Ancos

Differences among Spanish and Latin-American banana cultivars: Morphological, chemical and sensory characteristics

Physical (weight, size, shape, texture and colour), physicochemical (pH, titratable acidity, soluble solids, moisture content, total solids), chemical (soluble sugars, vitamin C, starch, pectic substances, volatile compounds) and biochemical (polyphenol oxidase and peroxidase activities, soluble proteins) characteristics and sensory attributes (appearance, flavour, odour, colour, firmness, acceptability) of banana (Musa cavendishii L.) fruits were studied in order to assess possible differences between nutritional properties and consumer acceptability of the local (Canarian) cultivars Enana and Gran Enana and the Latin-American (Colombian) Enana cultivar. Significant differences (P ≤ 0·05) were found between size and length of fruit, and between other objective measurements (lightness, yellowness, acidity, moisture content, starch, peroxidase and polyphenol oxidase activities, soluble sugars—sucrose, fructose, glucose). Also there were significant differences in vitamin C and protein content which established the higher nutritional value of the Spanish banana cultivars. The main compositional differences between the banana cultivars in terms of flavour were quantified. Purge and trap (head-space) analysis of the Spanish Enana cultivar showed it was the richest in the characteristic banana volatile aroma compounds. Sensory descriptive analysis discriminated between banana cultivars in terms of flesh colour and flesh sweetness; although panellists liked all cultivars, they preferred the Spanish Enana fruits (overall acceptability test).

Nutritional Approaches and Health-Related Properties of Plant Foods Processed by High Pressure and Pulsed Electric Fields

Consumers are more and more concerned about the nutritional and health-related characteristics of fruits and vegetables, as well as the safety of the food they eat. The processing of foods is becoming more sophisticated and diverse in response to the growing demand for quality foods. Consumers today expect food products to provide fresh-like appearance, convenience, variety, appropriate shelf-life and caloric content, reasonable cost, environmental soundness, high nutritional and functional quality. Nonthermal processing of fruit and vegetable has been revealed as a useful tool to extend their shelf-life and quality as well as to preserve their nutritional and functional characteristics. In the last ten years, there has been an increasing interest in nonthermal technologies as high pressure processing (HPP) and pulsed electric fields (PEF) to preserve fruit and vegetable products without the quality and nutritional damage caused by heat treatments. This review will contribute to inform many of the studies conducted to obtain a better understanding on the effects of some of these nonthermal processing technologies (high hydrostatic pressure and pulsed electric fields) applied to vegetable foods on their nutritional value and bioactive compounds related to health, including the results on micronutrient bioavailability studies and oxidative stress and inflammation biomarkers. These studies could contribute to select the most appropriate processing parameters to obtain safe, high-quality, nutritional, and functional vegetable food.

Effects of microwave heating on pigment composition and colour of fruit purees

Microwave energy was applied to inactivate the oxydoreductases peroxidase (POD, EC 1.11.1.7) and polyphenol oxidase (PPO, EC 1.14.18.1) in processed fruit products. Microwave blanching of papaya, strawberry and kiwi purees at various conditions of power and time produced inactivation of PPO and POD activities depending on the fruit and the heating conditions. Treatment at 850 W/60 s produced about 60% of POD inactivation for papaya and kiwi fruit. POD activity in strawberry, however, seemed to be more resistant to microwave inactivation; treatment at 850 W/60 s only achieved a loss of POD activity near 8%. Papaya oxidoreductases showed lower stability in the microwave treatments tested. Microwave blanching at 475 W/45 s produced about 75% inactivation of POD activity and nearly complete PPO inactivation. Kiwi fruit and strawberry purees exhibited similar inactivation of PPO – 32% at 475 W/30 s and 70% at 475 W/60 s. The decrease of PPO activity in both products was almost linear at constant power. This thermal treatment, however, directly affects the colour of the fruit pulps. Papaya, kiwi and strawberry purees suffered slight colour (CIE L* a*b*) changes. Carotenoid, chlorophyll and anthocyanin changes were evaluated by HPLC and related to objective colour. Microwave treatments produced small modifications of the quantitative and qualitative composition of carotenoids (in papaya) and anthocyanins (in strawberry). Chlorophylls (kiwi) showed significant degradation as a consequence of microwave heating. © 1999 Society of Chemical Industry

Bioaccessibility of tocopherols, carotenoids, and ascorbic acid from milk- and soy-based fruit beverages: influence of food matrix and processing.

A study was made of the effect of high-pressure processing (HPP) and thermal treatment (TT) on plant bioactive compounds (tocopherols, carotenoids, and ascorbic acid) in 12 fruit juice-milk beverages and of how the food matrix [whole milk (JW), skimmed milk (JS), and soy milk (JSy)] modulates their bioaccessibility (%). HPP (400 MPa/40 °C/5 min) produced a significant decrease in carotenoid and ascorbic acid bioaccessibility in all three beverages and maintained the bioaccessibility of tocopherols in JW and JS while decreasing it in JSy. TT (90 °C/30 s) produced a significant decrease in tocopherol and carotenoid bioaccessibility in all three beverages and increased the bioaccessibility of ascorbic acid. With regard to the food matrix, α-tocopherol and ascorbic acid bioaccessibility was greatest in JW beverages and lowest in JSy beverages, whereas no significant differences were found among the three beverages in terms of carotenoid bioaccessibility. HPP-treated samples showed higher tocopherol and carotenoid bioaccessibility than TT-treated samples, thus indicating that HPP combined with a milk matrix positively modulates the bioaccessibility of certain types of bioactive components of food, mainly those of a lipophilic nature.

Intake of Mediterranean vegetable soup treated by pulsed electric fields affects plasma vitamin C and antioxidant biomarkers in humans.

The bioavailability of vitamin C from pulsed electric fields (PEF)-treated vegetable soup in comparison with freshly made (FM) vegetable soup—gazpacho—and its impact on 8-epiPGF2α and uric acid concentrations in a human population were assessed. For this purpose six subjects consumed 500 ml PEF-treated vegetable soup/day, and six subjects consumed 500 ml FM vegetable soup/day for 14 days. On the first day of the study, the subjects drank the vegetable soup in one dose (dose–response study), and on days 2–14 they consumed 250 ml in the morning and 250 ml in the afternoon (multiple-dose–response study). Blood was collected every hour for 6 h on the first day and again on days 7 and 14. All blood samples were analyzed for vitamin C, 8-epiPGF2α, and uric acid. The maximum increase in plasma vitamin C occurred 3 h post-dose in both the PEF and the FM groups. Vitamin C remained significantly higher (P≤0.05) on days 7 and 14. The plasma 8-epiPGF2α concentration was significantly lower at the end of the study in both the PEF group (P=0.002) and the FM group (P=0.05). Plasma levels of vitamin C and 8-epiPGF2α were inversely correlated in both groups (r= − 0.549, P=0.018; and r= − 0.743, P=0.0004, respectively). To summarize, drinking two servings (500 ml) of PEF-treated or FM gazpacho daily increases plasma vitamin C and significantly decreases 8-epiPGF2α concentrations in healthy humans.

Effects of high pressure and mild heat on endogenous microflora and on the inactivation and sublethal injury of Escherichia coli inoculated into fruit juices and vegetable soup.

The objective of this study was to determine the effects of high-pressure treatments and mild temperatures on endogenous microflora and Escherichia coli CECT 515 artificially inoculated into orange and apple juices and vegetable soup. In general, the viability of aerobic bacteria was significantly reduced as pressure and temperature increased. Although the greatest reduction in the concentration of aerobic mesophilic vegetative cells was reached at 350 MPa and 60 degrees C, the same reduction occurred in fruit juices at 350 MPa and 20 degrees C. Yeasts and molds were below the level of detection (1 log CFU/ml) for the fruit juices and did not exceed 2 log CFU/ml for vegetable soup. Foods inoculated with E. coli were subjected to several treatments as indicated by the mathematical model applied in response surface methodology to obtain the maximum information with the minimum number of experiments. The number of tests for a range of pressures (150 to 350 MPa) and temperatures (20 to 60 degrees C) was limited to 11. The models were considered adequate because of satisfactory R2 values. The optimum process parameters (pressure and temperature) for a 6-log reduction of E. coli were obtained at 248.25 MPa and 59.91 degrees C in orange juice, 203.50 MPa and 57.18 degrees C in apple juice, and 269.8 MPa and 59.9 degrees C in vegetable soup. Sublethal injury of E. coli occurred as pressure and temperature increased. Nearly all of the E. coli cells were injured at 350 MPa and 20 degrees C in fruit juices and after all treatments in vegetable soup.

Changes in the structure and antioxidant properties of onions by high pressure treatment

Onions have antioxidant properties and they are an important source of bioactive compounds such as phenols. The aim of this work was to study the effect of high hydrostatic pressure (HHP) (100-600 MPa/1-3 min/25 °C) on the microstructure and antioxidant properties of onions (cv. Doux) and its relationship with changes in the extractability of potential health-related compounds. Cryo scanning electron microscopy was used to study the microstructure. Vitamin C, total phenolic content and antioxidant activity (DPPH˙, ABTS˙(+), FRAP) were also analyzed. Tonoplast, plasmalemma and cell walls were affected by the HHP treatment and it favored the diffusion of the cellular content to the intercellular spaces. Vitamin C did not show significant changes, whereas the extracted phenolic content and antioxidant activity increased at pressures of 300 or 600 MPa. Therefore, it could be concluded that HHP produced changes in membrane permeability and disruption of cell walls favoring the release of phenolic compounds from tissue and, in consequence, improving their extractability.

Carotenoid Pigments and Colour of Hermaphrodite and Female Papaya Fruits ( Carica papaya L) cv Sunrise During Post-Harvest Ripening

The predominant carotenoids in extracts of female and hermaphrodite Papaya fruits (Carica papaya L) Solo cv Sunrise were determined by high-performance liquid chromatography on a C 18 reversed-phase column using a diode-array detector. Three classes of carotenoids were separated and identified from the papaya extract without saponification; these were xanthophylls, hydrocarbon carotenoids and carotenol fatty acid esters. The xanthophylls were identified as trans-zeaxanthin, cryptoflavin and β-cryptoxanthin; other xanthophylls were detected in very small quantities. The major hydrocarbon carotenoid was identified as lycopene. Carotenol fatty acid esters were identified as carotenol fatty acid esters of β-cryptoxanthin, cryptoxanthin-5,6-epoxide, lutein, zeaxanthin and violaxanthin. There were no qualitative differences among the carotenoid pattern of female and hermaphrodite papaya fruits. Changes in carotenoid composition during ripening in hermaphrodite and female papaya fruits (cv Sunrise) were investigated in three different stages of ripeness. These changes could be shown in terms of Hunter colour values.

Evaluation of Chemical and Physical (High-Pressure and Temperature) Treatments To Improve the Safety of Minimally Processed Mung Bean Sprouts during Refrigerated Storage

The objective of this study was to compare the effects of combined high hydrostatic pressure and temperature treatments with different chemical sanitation treatments (water, sodium hypochlorite, and hydrogen peroxide) on the microbiological properties of mung bean sprouts. In a first study, the raw product was subjected to several combined high-pressure and temperature treatments for calculating a mathematical model by a response surface methodology. The number of pressure-temperature (150 to 400 MPa; 20 to 40 degrees C) combinations was limited to 10. In addition, a model system consisting of mung bean sprout juice was inoculated with Listeria monocytogenes (CECT 4032). Microbial inactivation with this model system was also investigated by a response surface methodology. The highest aerobic mesophilic bacteria and L. monocytogenes inactivation was achieved at maximum pressure and temperature (5.5 and 1.8 log cycles, respectively). In a second study, the effect of five different processing lines on the microbial load reduction of minimally processed mung bean sprouts during refrigerated storage was studied. All treatments reduced the initial population of aerobic mesophilic bacteria and fecal coliforms, with the physical treatment of 400 MPa and 40 degrees C being the most effective, showing initial reductions of 5.8 and 7.8 log CFU/ g, respectively. Recovery of bacteria from sprouts treated under these conditions was not observed during storage. However, the sprouts that received washing treatments with water, sodium hypochlorite, and hydrogen peroxide exhibited increases in aerobic mesophilic and fecal coliform counts after 3 days of storage at 4 degrees C.

Effects of freezing and canning of papaya slices on their carotenoid composition

An HPLC study of the carotenoid composition of fresh, frozen and canned papaya fruit slices was done. There were no qualitative differences between the carotenoid patterns of fresh and frozen papaya fruit slices (cultivar Sunrise). The major carotenoids found in papaya extracts were lycopene and carotenol fatty acid esters ofβ-cryptoxanthin andβ-cryptoxanthin-5, 6-epoxide. Other xanthophylls detected wereβ-crypto-xanthin,trans-zeaxanthin and cryptoflavin. It was possible to determine the quantitative losses of carotenoids in papaya slices as a result of the freezing process and frozen storage, since samples of these fruits were available before processing. The pigment pattern of the canned product showed lycopene as being a major pigment. Thermal treatment induced the degradation of carotenol fatty acid esters of xanthophylls. The freezing and canning processing of papaya slices led to significant decreases in the total carotenoids quantified by HPLC, with frozen female slices and canned samples showing lower amounts of pigments. Hunter colour values of frozen slices were similar to those of fresh papaya fruit slices.