Teresa Juan

Quality evaluation of Spanish rosemary (Rosmarinus officinalis) honey

The qualities of 27 samples of rosemary (Rosmarinus officinalis L.) honey from Aragon (Spain) was evaluated. Most samples showed a proper maturity considering the low moisture content. The low electrical conductivity and ash content were typical of pale honeys. Optical rotation was mostly levorotatory except for four samples with high sucrose content. Since the hydroxymethyl-furfural content was low and the diastase activity was high, a good freshness was estimated. The total acidity (below 40 meq/kg) indicated absence of undesirable fermentation; additionally the mean pH around 3·70 is usual in this kind of honey. The fructose/glucose ratio was 1·17 ± 0·01 and sucrose content averaged 1·97 ± 0·27%. The analysis of sediment showed a very low honeydew indication which explains the low trisaccharide content found in the samples by GC-FID quantitation.

Physicochemical attributes and pollen spectrum of some unifloral Spanish honeys

In the present work a total of 19 unifloral Spanish honeys were studied and botanically typified: willow (Salix sp.), sainfoin (Onobrychis viciifolia Scop.), chickweed (Hypecoum sp.), crucifer (Brassica type), fruiter (Prunus sp.), thyme (Thymus sp.), blueweed (Echium sp.), spike lavender (Lavandula latifolia Med.), French lavender (Lavandula stoechas L.), and vetch (Vicia sativa L.). Unifloral honeys were considered as such whenever the dominant pollen was found at over 45% of total pollen, except for lavender and thyme types of honey where a finding above 15% of Lavandula or Thymus pollen, respectively, was enough to typify them. All samples were organoleptically examined and the following determinations were carried out: moisture, optical rotation, electrical conductivity, ash, hydroxymethylfurfural, diastase activity, pH, acidity (free, lactone, and total) and carbohydrate composition. These samples were found to meet all major national and international honey specifications.

Natural Occurrence of Fusarium Species, Fumonisin Production by Toxigenic Strains, and Concentrations of Fumonisins B1 and B2 in Conventional and Organic Maize Grown in Spain

Sixty samples of corn from both conventional and organic farms were tested for internal fungal contamination. Molds were identified to genus, and those belonging to the genus Fusarium were identified to species. Twenty isolates of Fusarium verticillioides were tested with a high-performance liquid chromatography-naphthalene dicarboxaldehyde-fluorescence method for their ability to produce fumonisins B1 and B2. The internal fungal infection in organic maize (63.20%) was significantly higher than that in conventional maize (40.27%) (P < 0.05). However, the distribution of fungal genera indicated a significantly higher prevalence of Fusarium in conventional (34.93%) than in organic (18.15%) maize, making Fusarium the predominant fungus in conventional maize. This difference in mold distribution between organic and conventional maize was attributed to the difference in cultivation system. The dominant Fusarium species in both conventional and organic samples was F. verticillioides. There were no significant differences in the ability of 20 selected isolates of F. verticillioides to produce fumonisins on conventional or organic corn. Up to 13.3% of the conventional corn samples contained fumonisins B1 and B2 at mean concentrations of 43 and 22 ng/g, respectively. Organic corn samples had somewhat lower levels of contamination: 35 ng/g fumonisin B1 and 19 ng/g fumonisin B2 (P > 0.05). The organic farming system, with well-balanced crop rotation, tillage, and compost fertilization, produced corn that was less likely to be contaminated with Fusarium species, although no significant difference in fumonisin concentrations was found between the two types of contaminated corn.

Tocopherol Concentration in Almond Oil: Genetic Variation and Environmental Effects under Warm Conditions

The concentration of the different tocopherol homologues in almond kernel oil was determined in 17 almond cultivars grown in two different experimental orchards, in Spain and Morocco. The three main homologues showed a large variability, ranging from 210.9 to 553.4 mg/kg of oil for α-tocopherol, from 4.64 to 14.92 mg/kg for γ-tocopherol, and from 0.2 to 1.02 mg/kg for δ-tocopherol. The year effect was significant, independent of the experimental site, for all homologues and total tocopherol, the values of α-tocopherol, γ-tocopherol, and total tocopherol being higher in 2009 than in 2008, whereas the value of δ-tocopherol was higher in 2008. The location effect was also significant, the values of γ- and δ-tocopherol being higher in Spain than in Morocco, whereas for α-tocopherol the location effect was dependent on the genotype. These effects could not be explained by the temperature differences between sites, but probably other undetermined environmental factors might explain the effect of the location, such as rainfall and irrigation supplementation during fruit growing and ripening.

Influence of Agricultural Practices on the Contamination of Maize by Fumonisin Mycotoxins

The objective of the present work was to investigate the effect of different agricultural practices on the contamination of maize by fumonisin mycotoxins. Corn samples were collected from 16 maize fields located in Aragón (northeastern Spain) during the 2007 crop year. Corn samples were collected from each field five times at different maturation stages: F1, day 0 (milky corn); F2, day 15; F3, day 30 (yellow corn); F4, day 45; and F5, ripe corn at harvest. The agricultural practices evaluated were type of seed (conventional and transgenic), planting method (dry and wet planting), tillage system (plowing and minimum tillage), type of irrigation (flood and sprinkler), residue management of preceding crop (removal and burial), nitrogen fertilization level (kg N per ha), and harvest date. Mycotoxin analysis was carried out with the ROSA Fumonisin test, which measures both fumonisin B1 and B2 by lateral flow immunoassay. No fumonisins were detected in milky corn (F1 and F2 stages). Only one field had fumonisins in F3 yellow corn (1,037 microg/kg); this field was part of the only farm affected by borer insects. One-third of fields had fumonisins at the F4 stage (363 microg/kg), and 62.5% of the fields were positive for fumonisins at the F5 harvest stage (520 microg/kg). Wet planting and the removal of debris from the previous crop significantly lowered the risk of fumonisin in corn. The use of insect-resistant maize seeds tended to reduce fumonisin levels. However, higher levels of nitrogen fertilizer had a tendency to increase fumonisin levels in corn. Tillage system, type of irrigation, and harvest date had no clear effect on fumonisin levels.

Fermentation Problem in Spanish North-Coast Honey

Twenty-one samples from the Cantabrian coast were analyzed to establish their microbiological quality and fermentation tendency. In a food with a very low free-water content like honey, microbiological growth is only possible when there is an increase in water activity. Since most of the samples studied were not extensively granulated, the risk of fermentation is mostly due to high water content. Among our samples, only two had a water content below 17.1% (no risk of fermentation), whereas the high water activity of the rest of the samples indicates the possibility of microbial growth. In fact, four of the samples analyzed showed a moisture content over the Spanish maximum legal limit, which means a high risk of fermentation. The absence of Enterobacteriaceae, coliforms, and Escherichia coli in our samples indicates an appropriate cleanliness during extractions and handling of honey. No Salmonella or Shigella were found. The relationship between water activity and mold and yeast counts found for the honeys analyzed allowed us to divide our samples in two groups: honeys with a high or a low risk of fermentation. Changes observed during storage of the samples confirmed this classification.

Plasticity and stability in the major fatty acid content of almond kernels grown under two Mediterranean climates.

Summary Oil contents and fatty acid compositions were determined in 17 almond cultivars growing under two different Mediterranean conditions, in northeast Spain and in central Morocco. The major differences were irrigation management in Spain and higher temperatures in Morocco. Although a cultivar effect was observed for some compounds, the general trend was for an increase in total oil content [58.65% vs. 55.58% (w/w)] and in the percentage of oleic acid [71.1% vs. 68.62% (w/w)] in those kernels harvested in Spain, probably due to having lower temperatures and better water status. As the total oil content and level of oleic acid in almond oil are the major parameters for higher quality almond kernels, these results emphasise the need to optimise the management of almond orchards to improve kernel quality, not only from the commercial and industrial points of view, but also because of their healthgiving properties.

Xenia effects on oil content and fatty acid and tocopherol concentrations in autogamous almond cultivars.

The increasing utilization of self-compatible almond cultivars in solid plantings of a single genotype has raised the question of the effect of the pollen source on the kernel quality of these new autogamous cultivars. Thus, the effect of two different pollen sources, in addition to their own pollen, on the oil content and fatty acid and tocopherol concentrations was studied in four autogamous almond genotypes. The oil content was not affected by the pollination treatment, but self-pollination resulted in significantly higher values for oleic acid. For the tocopherol homologues, the alpha-tocopherol content of the self-pollinated kernels was intermediate between those obtained after cross-pollination with the two foreign pollens, but the self-pollinated kernels had higher values of delta-tocopherol than the cross-pollinated kernels. Thus, the effect of the pollen source was shown to have a clear effect on the fatty acid composition but not on the oil or tocopherol contents of the almond kernels, with an increased quality of the kernels produced after self-pollination because of a higher oleic/linoleic acid ratio.

Inhibition of Fusarium Growth and Mycotoxin Production in Culture Medium and in Maize Kernels by Natural Phenolic Acids

The possible role of natural phenolic compounds in inhibiting fungal growth and toxin production has been of recent interest as an alternative strategy to the use of chemical fungicides for the maintenance of food safety. Fusarium is a worldwide fungal genus mainly associated with cereal crops. The most important Fusarium mycotoxins are trichothecenes, zearalenone, and fumonisins. This study was conducted to evaluate the potential of four natural phenolic acids (caffeic, ferulic, p-coumaric, and chlorogenic) for the control of mycelial growth and mycotoxin production by six toxigenic species of Fusarium . The addition of phenolic acids to corn meal agar had a marked inhibitory effect on the radial growth of all Fusarium species at levels of 2.5 to 10 mM in a dose-response pattern, causing total inhibition (100%) in all species except F. sporotrichioides and F. langsethiae . However, the effects of phenolic acids on mycotoxin production in maize kernels were less evident than the effects on growth. The fungal species differed in their responses to the phenolic acid treatments, and significant reductions in toxin concentrations were observed only for T-2 and HT-2 (90% reduction) and zearalenone (48 to 77% reduction). These results provide data that could be used for developing pre- and postharvest strategies for controlling Fusarium infection and subsequent toxin production in cereal grains.

Aspectos cualitativos de la composición de los cultivares de almendro de Mallorca (España)

espanolSe han determinado el contenido en aceite, el porcentaje de los diferentes acidos grasos del aceite y la concentracion de los tres homologos mayoritarios de tocoferol en las almendras de 23 cultivares de Mallorca. Todos estos parametros mostraron una gran variabilidad, con una oscilacion de 47,40-56,78% del peso seco para el aceite, de 58,65-78,44% del total de aceite para el acido oleico, de 12,01-29,40% para el acido linoleico, de 5,38-7,06% para el acido palmitico, de 1,88-3,71% para el acido estearico, de 0,38- 0,61% para el acido palmitoleico, de 258,5-500,2 mg kg-1 aceite para el α-tocoferol, de 0,02-1,13 mg kg-1 aceite para el δ-tocoferol, de 1,89-20,8 mg kg-1 aceite para el γ-tocoferol y de 260,41-522,13 mg kg-1 aceite para el total de tocoferoles. Esta variabilidad esta de acuerdo con los niveles de variabilidad de estos componentes analizados en cultivares de almendro de diversa procedencia geografica, pero se obtuvieron unos valores inferiores a la media en el contenido en aceite, el porcentaje de acido oleico y la concentracion de tocoferoles, lo que puede recomendar una comercializacion rapida de las almendras de Mallorca, asi como su uso para determinadas utilizaciones por su contenido en aceite EnglishOil content, percentage of the different fatty acids and concentration on the three main tocopherol homologs were determined for the almonds of 23 cultivars of Majorca. All these parameters showed great variability, with a range of 47.40-56.78% of dry matter for oil, of 58.65-78.44% of total oil for oleic acid, of 12.01-29.40% for linoleic acid, of 5.38-7.06% for palmitic acid, of 1.88-3.71% for stearic acid, of 0.38- 0.61% for palmitoleic acid, of 258.5-500.2 mg kg-1 oil for α-tocopherol, of 0.02-1.13 mg kg-1 oil for δ-to - copherol, of 1.89-20.8 mg kg-1 oil for γ-tocopherol, and of 260.41-522.13 mg kg-1 oil for total tocopherols. This variability agrees with the levels of variability of these components analyzed in almond cultivars of different geographical origin, but the values obtained were lower than the average for the oil content, the percentage of oleic acid and the concentration of tocopherols, a fact that may recommend a rapid commercialization of the Majorcan almonds, as well as their utilization for specific confectioneries due to their oil content