Milica Kač

Dietary fibre content of dry and processed beans

Abstract Common beans ( Phaseolus vulgaris L.) are a good source of protein, vitamins, minerals and especially dietary fibre. As beans are never eaten raw, the effects of soaking, cooking, soaking–cooking and canning on soluble, insoluble and total dietary fibre contents of beans are studied. Total dietary fibre content was determined by enzyme-gravimetric method. The fraction of insoluble dietary fibre was corrected for the content of resistant starch, determined as part of the total starch in insoluble fibre. The results indicate that thermal processing decreased the insoluble fibre content, and consequently the total dietary fibre content of beans. Soaking and cooking of beans significantly ( P ⩽0.05) increased the resistant starch content. The data on dietary fibre content of processed food are much more relevant than those of raw food. Thus food composition tables should contain as much data on processed food as possible.

Solid-phase microextraction of hop volatiles ☆: Potential use for determination and verification of hop varieties

The composition of hop essential oil is an important tool for evaluation of hop quality. As each hop variety has a typical essential oil pattern (fingerprint), hop oil analyses can be used to distinguish between hop varieties. The headspace solid-phase microextraction (SPME) method as described in this contribution is a simple sample preparation technique and represents an alternative procedure for essential oil fingerprint determination. Different SPME parameters (extraction temperature, extraction time and sample mass) were studied and the results were compared with those obtained by the routine distillation method. It is shown that SPME results can be used for determination and verification of varieties grown in Slovenia by means of principal components analysis.

Determination and verification of hop varieties by analysis of essential oils

Abstract The composition of essential oil in hops depends mainly on hop variety and less on growing, processing and storage conditions. Therefore the data on the composition can be used to distinguish between hop varieties. During the years 1998–2000, 78 samples of the commonly grown varieties in Slovenia were analyzed by gas chromatography. Research was focused on the selection of suitable components characteristic of the varieties in question. Since the changes in essential oil composition due to ageing are the most important interferences for determination of the varieties, these influences were successfully suppressed using the so-called indexes. Sixteen representative peaks were selected, indexes were calculated and processed by cluster analysis and principal component analysis. The developed method was shown to be effective on all hop varieties important in Slovenia and gave excellent results in daily laboratory practice.

Yield of early white cabbage grown under mulch and non-mulch conditions with low populations of onion thrips (Thrips tabaci Lindeman)

The damage caused by Thrips tabaci to a susceptible hybrid of early white cabbage was studied in field experiments undertaken during 2004 and 2005. The three treatments tested were beds of cabbage mulched with: (1) barley straw, (2) hay, and (3) black polyethylene (PE) sheeting. Bare-soil (un-mulched) beds were used as the control treatment. One early and one late experiment were performed in both years. In the early experiments, the mulches were applied at the start of the experiment, whereas in the late experiments the soil was first covered with black polyethylene for approximately 1 month. In both years, the springs were cold and wet, and so the thrips appeared late and their numbers were low. The highest mean actual weight and trimmed weight were recorded for cabbage grown in 2005 under PE mulch (actual early: 995 g, actual late: 1184 g, trimmed early: 870 g, trimmed late: 1056 g). Year 2004 gave lower values (110g for both variables) under barley straw and hay mulch (165 g and 160 g, respectively). There was no evidence of an allelopathic effect of water extracts of either barley straw or hay.

Distribution of Aeolothrips intermedius Bagnall (Thysanoptera: Aeolothripidae) and its potential prey Thysanoptera species on different cultivated host plants

The results of the monitoring of Thysanoptera species on cultivated plants in Slovenia (2000–2001), Croatia (1994–1996), and Serbia and Montenegro (1988–2003) are presented in this study. The aim of the investigation was to study the host plant distribution of the predator Aeolothrips intermedius Bagnall and its potential prey. Banded thrips were found on 30 different host plant species belonging to 16 botanical families, always in mixed populations with phytophagous or facultative phytophagous insects (including 18 Thysanoptera species). On the vegetative parts of the cultivated plants, banded thrips were found less numerous in spite of the massive population of some harmful thrips species. This indicates highly important role of pollen as alternative food for Aeolothrips intermedius.

Nontarget effect of entomopathogenic nematodes on larvae of twospotted lady beetle (Coleoptera: Coccinellidae) and green lacewing (Neuroptera: Chrysopidae) under laboratory conditions.

ABSTRACT The nontarget effect of Steinernema feltiae, Steinernema carpocapsae, Heterorhabditis bacteriophora, and three mixed suspensions of two species of entomopathogenic nematodes on the larvae of the twospotted lady beetle, Adalia bipunctata (L.) (Coleoptera: Coccinellidae), and on the larvae of the lacewing Chrysoperla cornea (Stephens) (Neuroptera: Chrysopidae), were studied in a laboratory bioassay. The assay was performed at three temperature (15, 20, and 25°C) and at three different concentrations of the suspension (500, 2,500, and 5,000 infective juveniles [IJs]/ml). The larvae of A. bipunctata were more susceptible to nematode attack than the larvae of C.. cornea. Four days after treatment, significantly the lowest mortality of A.. bipunctata and C.. cornea larvae was recorded at 15°C, whereas no significant differences were noted between 20 and 25°C. At 500 IJs/ml, the nematodes had significantly the lowest nontarget effect on the larvae of both aphid predators, whereas no significant differences in this regard were established between 2,500 and 5,000 IJs/ml. We conclude that the entomopathogenic nematodes under investigation exhibit a pronounced nontarget effect on the larvae of both predators mentioned.

Thermodynamic functions of activation for viscous flow of some monosaccharides in aqueous solutions

Abstract The viscosities of aqueous solutions of some monosaccharides D-pentoses and (D-hexoses) were measured up to 2.5 mol kg −1 in the temperature range from 293.15 to 318.15 K. On the basis of Eyrings theory of the transition state, the relations for the thermodynamic functions of activation for viscous flow of binary liquid mixtures, i.e. molar Gibbs free energy, Δ # Ḡ 1,2 , entropy, Δ # S 1,2 , and enthalpy, Δ # H 1,2 , and for the partial molar quantities of activation for viscous flow of solute and solvent, respectively, were obtained. Thereby, the dependence of the molar thermodynamic functions of activation for a viscous flow of solution against the solute mole fraction was given as a second-degree polynomial. It was shown that the linear correlation coefficient β Y , ( Y denotes G , H or S ), is given by the difference between the partial molar activation parameter of the solute at infinite dilution and the respective molar quantity of the pure solvent. In addition, correlations between the coefficient β Y and the viscosity coefficient B and/or temperature derivative of the viscosity coefficient B were found. For the solutions investigated, the molar thermodynamic activation parameters for viscous flow were found to be linearly dependent on the solute mole fraction, which means that the partial molar quantities of activation of the solutes are concentration independent.

Effect of temperature on efficacy of three natural substances to Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)

Abstract Azadirachtin, refined rape oil and slaked lime – three natural substances with insecticidal potential – were tested under laboratory conditions for their efficacy against larvae and adults of Colorado potato beetle, Leptinotarsa decemlineata, at 15°C, 20°C, and 25°C. General statistical analysis (all developmental stages and all insecticidal substances taken into account) was performed on the results of the mortality rates of the individuals and no statistically significant differences between the temperatures were observed on the fifth day after application. At all temperatures, the influence of insecticidal substances in question as well as the interaction between the insecticidal substance and the developmental stage of the pest on mortality rates were significant. The individual statistical analysis (a specified developmental stage of the pest at a specified temperature) revealed the maximum efficacy of the refined rape oil at 15°C and 20°C, the adults being the most sensitive developmental stage (mortality rate about 90%). Other substances tested were less effective, and in general the mortality rate of either larvae or adults did not exceed 50%. In the case that the efficacy of the refined rape oil in controlling the population of the adults of the Colorado potato beetle is confirmed also in field trials, this could be the basis for a better strategy in controlling the overwintered Colorado potato beetles on potato.

Three natural substances for use against Alternaria cichorii on selected varieties of endive: antifungal agents, plant strengtheners, or foliar fertilizers? Drei gegenüber Alternaria cichorii an ausgewählten Endiviensorten wirkende natürliche Substanzen: antimykotische Agenzien, Pflanzenstärkungsmittel oder Blattdünger?

During 2004 and 2005 the activity of sulphur, soya lecithin, and salicylic acid on endive and on the fungus Alternaria cichorii were investigated in a field block experiment. In both years, the plants sprayed five times with soya lecithin or three times with sulphur yearly, were significantly less infected than untreated plants. In 2005, the effect of salicylic acid (five sprays) was also shown to be satisfactory. Compared to the untreated plants, the plants treated with natural substances exhibited higher total mass as well as higher net mass. In both years a significant positive correlation was established between the total mass of the plants and yield loss (r2 = 0.66 in the 2004 soya lecithin treatment, and r2 = 0.62 in the 2005 salicylic acid treatment). In 2005, when the fungus occurred to a higher extent, a lower correlation (r2 = 0.30) was confirmed between yield loss and the extent of infection on the exterior leaves. The variety Eros was the most heavily infected with the fungus in both years, while the varieties Escariol grüner, Pancalieri, Avance, and Palmira showed greater resistance to infection with A. cichorii. The varieties Perfect, Pancalieri, and Avance had the highest net mass, while only the first of them showed the highest total mass.ZusammenfassungIn den Jahren 2004 und 2005 wurde die Wirkung von Schwefel, Sojalecithin und Salicylsäure auf die Endivie und ihr pilzliches Pathogen Alternaria cichorii in Blockversuchen im Feld untersucht. In beiden Jahren waren fünfmal mit Sojalecithin oder dreimal mit Schwefel gespritzte Endivien signifikant geringer infiziert als unbehandelte Pflanzen. Im Jahr 2005 wurde eine positive Wirkung nach fünfmaliger Anwendung von Salicylsäure beobachtet. Im Vergleich zur unbehan-delten Kontrolle wiesen die behandelten Pflanzen höhere Gesamt- und Nettogewichte auf. In beiden Jahren waren Gesamtgewicht der Pflanzen und Ertragsverluste positiv korreliert (r2= 0.66 in der Sojalecithin-Behandlung 2004 und r2= 0.62 in der Salicylsäure-Behandlung 2005). Im Jahr 2005 mit höheren Infektionsraten wurde eine geringere positive Korrelation (r2 = 0.30) zwischen Ertragsverlusten und Infektionsraten der Hüllblätter beobachtet. Die Sorte Eros war in beiden Jahren am stärksten infiziert, während die Sorten Escariol grüner, Pancalieri, Avance und Palmira resistenter gegenüber A. cichorii waren. Die Sorten Perfect, Pancalieri und Avance erreichten das höchste Nettogewicht und Perfect das höchste Gesamtgewicht.