Calcium salts and heat treatment for quality retention of fresh-cut ‘Galia’ melon

‘Galia’ melon is one of the most common cv produced in Spain destined for fresh consumption and/or for the fresh-cut processing industry. Nevertheless, fresh-cut melon is very susceptible to softening during storage, even under chilling and modified atmosphere packaging. This softening process is related to Ca levels in fruit tissue. After preparing trapezoidal shaped sections of ‘Galia’ melons, the pieces were dipped for 1 min a 60 °C in Ca chloride, citrate, lactate, ascorbate, tartrate, silicate, propionate or acetate using a Ca concentration equivalent to 0.4% (0.15 g g⁻¹) pure Ca chloride, combined with 50 mg L⁻¹ H₂O₂ for controlling microbial growth. Dipping in sterile distilled water (without Ca salt) at 60 °C for 1 min was used as a control treatment. Firmness, pectin methylesterase and polygalacturonase activity, Ca content, microbial growth, respiration rate, and sensory evaluation, were evaluated throughout 10 days of storage at 5 °C under a passive modified atmosphere reaching 4.5 kPa O₂ and 14.7 kPa CO₂. At the end of shelf life, Ca ascorbate, chloride and lactate provided melon pieces with a lower respiration rate, increased tissue total Ca content, and maintained a good firmness. In addition, those Ca salts reduced microbial growth. Sensory parameters, such as flavor perception, were kept above the upper limits for marketability. A considerable loss of flavor was found in all treatments except with Ca chlorine, lactate and ascorbate, the only treatments found acceptable from the consumer point of view.     

Spatial distribution of carbon over an eroded landscape in southwest Wisconsin

Spatial distribution of carbon (C) within a soil profile and across a landscape is influenced by many factors including vegetation, soil erosion, water infiltration, and drainage. For this reason, we attempted to determine the soil C distribution of an eroded soil. A three-dimensional (3D) map of a 0.72 ha field with a Dubuque silt loam soil which has three levels of erosion (slight, moderate, and severe) was developed using soil distribution and profile data collected using a profile cone penetrometer (PCP). This map displays the distribution of the total depth of the Ap and Bt1 horizons and the upper part of the 2Bt2 horizon. A map of soil C distribution was created for this landscape using C content information obtained from soil samples. Based on the C distribution in the upper two horizons, a 3D viewing was developed of soil C distribution for this eroded landscape. The 3D assessment of C distribution provides a better means of assessing the impact of soil erosion on C fate. It was estimated that there were 52 Mg ha⁻¹ of total C in the surface (Ap) horizon and 61 Mg ha⁻¹ in the Bt1 horizon for the 0.72 ha area. This increase in C with depth in the soil can be attributed to an increase in clay content and C leaching resulting in stable carbon–clay complexes. The C content was 16.0, 17.5, and 19.0 g kg⁻¹ for the Ap horizon in the slight, moderate, and severe erosion levels, respectively. However, it was estimated that the total C amount in the respective Ap horizons was 28, 14, and 10 Mg ha⁻¹ for the slight, moderate, and severe areas. The Bt1 horizon had 31, 19, and 11 Mg ha⁻¹ of C in the slight, moderate, and severe areas, respectively. For the 0.72 ha area, 25% was severely eroded with 31 and 44% being moderate and slight, respectively. Soil C distribution information, such as that presented here, can be very valuable for soil management and could be used to determine possible C storage credits.     

A kinetic study of p-cresol oxidation by quince fruit polyphenol oxidase

The monophenolase activity of quince pulp polyphenol oxidase was characterized by extracting samples using a combination of a two-phase partition step in Triton X-114, followed by a PEG 8000/phosphate partition step, and a final ammonium sulfate fractionation between 30 and 75%. The purification method avoids the loss of cresolase activity described in another quince pulp polyphenol oxidase. The activity was characterized by a lag period, whose duration depended on the substrate concentration, the pH, and the presence of catalytic amounts of o-diphenol. By increasing the concentration of o-diphenols, it was possible to evaluate the enzyme activation constant, K(act), which showed a value of 4.5 microM for 4-methylcatechol. A general kinetic mechanism for this enzyme is used to explain the loss of activity that normally occurs during quince pulp polyphenol oxidase purification.     

Effect of enzymatic treatment of extracted sunflower proteins on solubility, amino acid composition, and surface activity

Industrial proteins from agriculture of either animal or vegetable origin, including their peptide derivatives, are of great importance, from the qualitative and quantitative point of view, in food formulations (emulsions and foams). A fundamental understanding of the physical, chemical, and functional properties of these proteins is essential if the performance of proteins in foods is to be improved and if underutilized proteins, such as plant proteins (and their hydrolysates and peptides derivatives), are to be increasingly used in traditional and new processed food products (safe, high-quality, health foods with good nutritional value). In this contribution we have determined the main physicochemical characteristics (solubility, composition, and analysis of amino acids) of a sunflower protein isolate (SPI) and its hydrolysates with low (5.62%), medium (23.5%), and high (46.3%) degrees of hydrolysis. The hydrolysates were obtained by enzymatic treatment with Alcalase 2.4 L for DH 5.62 and 23.5% and with Alcalase 2.4 L and Flavorzyme 1000 MG sequentially for DH 46.3%. The protein concentration dependence on surface pressure (surface pressure isotherm), a measure of the surface activity of the products (SPI and its hydrolysates), was obtained by tensiometry. We have observed that the degree of hydrolysis has an effect on solubility, composition, and content of the amino acids of the SPI and its hydrolysates. The superficial activity and the adsorption efficiency were also affected by the degree of hydrolysis.     

Limited enzymatic hydrolysis can improve the interfacial and foaming characteristics of beta-conglycinin

In this contribution, we have determined the effect of limited enzymatic hydrolysis on the interfacial (dynamics of adsorption and surface dilatational properties) and foaming (foam formation and stabilization) characteristics of a soy globulin (beta-conglycinin, fraction 7S). The degree of hydrolysis (DH = 0, 2, and 5%), the pH of the aqueous solution (pH = 5 and 7), and the protein concentration in solution (at 0.1, 0.5, and 1 wt %) were the variables studied. The temperature and the ionic strength were maintained constant at 20 degrees C and 0.05 M, respectively. The rate of adsorption and surface dilatational properties (surface dilatational modulus, E, and loss angle) of beta-conglycinin at the air-water interface depend on the pH and DH. The adsorption decreased drastically at pH 5.0, close to the isoelectric point of beta-conglycinin, because of the existence of a lag period and a low rate of diffusion. The interfacial characteristics of beta-conglycinin are much improved by enzymatic treatment, especially in the case of acidic aqueous solutions. Hydrolysates with a low DH have improved functional properties (mainly foaming capacity and foam stability), especially at pH values close to the isoelectric point (pI), because the protein is more difficult to convert into a film at fluid interfaces at pH approximately equal to pI.     

Antimicrobial activities and cytotoxicity of the brown alga Cystoseira tamariscifolia

The hexane, ethyl ether and dichloromethane fractions of the brown alga Cystoseira tamariscifolia extract showed interesting antimicrobial activities and cytotoxicity.     

First results on spawning, larval rearing and growth of the wedge sole (Dicologoglossa cuneata) in captivity, a candidate species for aquaculture

The wedge sole is a target species in the fisheries of the Gulf of Cadiz (Spain). Having reared them to commercial size, we have studied reproduction and breeding in captivity of the wedge sole in this work here. The breeders adapt easily to captivity, and they can spawn in less than 1 year in captivity. The relative fecundity is relatively high, 1.06–2.33 · 10⁶ eggs kg⁻¹ per spawning season (mean 1.6 ± 0.1). Larval SGR is high, 7.2 ± 0.2% day⁻¹ (range 5.8–9.1), similar to other cultured flatfish species. In 1 year, some individuals reach market size and can release eggs, registering SGRs of 1.39–1.66% day⁻¹ (mean 1.56 ± 0.01). This species presents some very different characteristics with respect to other farmed flatfishes (turbot, halibut and Senegal sole, mainly), so that it is necessary to develop new techniques to optimise its cultivation. In the present work, the first results are presented on the biology of the wedge sole in captivity.     

Cultivation of whitebait (Galaxias maculatus) in Chile

The growth of commercial aquaculture in Chile generated an income of $2.300 million USD in exports in 2005. Currently, 15 different species are cultivated commercially, of which seven are native; these had returns of 185 million USD. Among these native species is Galaxias maculatus (whitebait), which is endemic to Chile and figures significantly in Chilean fishing statistics. Since the 1990s, the School of Aquaculture of the Universidad Catolica de Temuco has been developing cultivation of this native species. This work presents the state of the art of the cultivation of this fish.     

Simple genetic inheritance conditions resistance to <Emphasis Type="Italic">Liriomyza sativae</Emphasis> in melon

The leafminer Liriomyza sativae (Diptera: Agromyzidae) stands out as the main plant health problem in melon in the Northeast region of Brazil, which is the main region for production and export of the fruit. Genetic resistance of plants is an important strategy in management of this pest. The plant BAGMEL 56-R was selected as a new source of resistance to L. sativae through antibiosis; this resistance is characterized by the death of larvae soon after they begin feeding on the leaf mesophyll; the result is leaf mines that are small and insignificant in terms of yield reduction. Lines with contrasting levels of resistance were obtained from the progenies of this source of resistance through successive self-pollinations, conducted by the pedigree breeding method. Through the segregation pattern of the progenies and the test cross, the genetic nature of resistance was determined; one gene with complete dominance conditions resistance. The name Liriomyza sativae resistance and the symbol Ls are suggested to represent this new gene. In addition, through a non-preference test with lines in contrast for antibiosis and the susceptible hybrid ‘Goldex’, the presence of antixenosis was observed in this source of resistance. Probably, these different types of resistance in the source BAGMEL 56-R are associated with distinct defense mechanisms. Therefore, with this new source, introgression of resistance to L. sativae in elite lines or commercial hybrids of melon is possible.