An effect of suint on sheep wool impedance and heat resistance values

ABSTRACT

The phenomenon of impedance finds an application in many areas of science; however, no studies relate to wool. Thus, the aim of the study was an examination of an effect of from the presence of suint layer on sheep wool fibers on impedance and heat resistance values. Electrical characteristics (impedance [Ω]) and heat resistance were compared in terms of wool washing effect. The impedance of wool samples was tested in the frequency range of 10 Hz to 1 MHz. In order to measure electrical characteristics and heat resistance values, five samples of greasy wool were collected from different sheep breeds, standardized by weight. After the analyses, the samples were washed and reexamined. The results showed significant differences in the impedance between the greasy and washed wool samples in each of the tested breed (p > 0.05). The suint layer reduces the impedance level, which was also confirmed by a heat resistance test results demonstrating that absence of suint layer on wool fibers significantly reduced this feature value (p > 0.05). This was also reflected in the weight differences between the examined wool samples before and after their washing.     

Intra- and interspecific mineral composition variability of commercial instant coffees and coffee substitutes: Contribution to mineral intake

The present paper reports the amount and estimated daily mineral intake of nine elements (Ca, Mg, K, Na, P, Fe, Mn, Cr and Ni) in commercial instant coffees and coffee substitutes (n = 49). Elements were quantified by high-resolution continuum source flame (HR-CS-FAAS) and graphite furnace (HR-CS-GFAAS) atomic absorption spectrometry, while phosphorous was evaluated by a standard vanadomolybdophosphoric acid colorimetric method.Instant coffees and coffee substitutes are rich in K, Mg and P (>100 mg/100 g dw), contain Na, Ca and Fe in moderate amounts (>1 mg/100 g), and trace levels of Cr and Ni. Among the samples analysed, plain instant coffees are richer in minerals (p < 0.001), except for Na and Cr. Blends of coffee substitutes (barley, malt, chicory and rye) with coffee (20–66%) present intermediate amounts, while lower quantities are found in substitutes without coffee, particularly in barley.From a nutritional point of view the results indicate that the mean ingestion of two instant beverages per day (total of 4 g instant powder), either with or without coffee, cannot be regarded as important sources of minerals to the human diet, although providing a supplementation of some minerals, particularly Mg and Mn in instant coffees. Additionally, and for authentication purposes, the correlations observed between some elements and the coffee percentage in the blends, with particular significance for Mg amounts, provides a potential tool for the estimation of coffee in substitute blends.     

New insights on the metabolism of ricinoleic acid in ruminants

Dairy goats were fed a total mixed ration with or without the inclusion of castor oil [40 g/kg of dry matter (DM)] to study the metabolism of ricinoleic acid (12-OH,cis-9–18:1). Ten goats, at 39.7 ± 4.0 d in milk, were individually penned and allocated at random to the 2 experimental diets. Goats were manually milked twice a day. Milk fatty acids (FA) were analyzed as methyl esters and hydroxyl groups were derivatized in trimethylsilyl ethers. Apart from ricinoleic acid, 6 FA were only detected in the milk of the castor oil group. Ricinoleic acid composed 0.3% of total FA in milk of the castor oil group, whereas the hydroxy-FA (8-OH-14:0, 10-OH-16:0, and 12-OH-18:0) and oxo-FA (8-oxo-14:0, 10-oxo-16:0, and 12-oxo-18:0) reached 7.5% of total FA in milk. We anticipate that these FA were derived from the metabolism of ricinoleic acid, although it was not clear if they were produced in the rumen or in the tissues. To confirm that, we conducted in vitro batch incubations repeated for 3 consecutive weeks with castor oil (40 g/kg of DM) and strained rumen fluid from 2 fistulated sheep. To examine the products formed over time, incubation tubes were stopped at 0, 6, 12, 24, 48, and 72 h. The results of the in vitro experiment showed that ricinoleic acid was metabolized in the rumen at a slow rate and the main products formed were 12-OH-18:0 and 12-oxo-18:0, by hydrogenation of the cis-9 double bond, followed by oxidation of the hydroxyl group, respectively. Our results suggest that the 12-OH-18:0 and 12-oxo-18:0 escape rumen and are further metabolized through partial β-oxidation in ruminant tissues. We propose that the 10-OH-16:0 and 8-OH-14:0 found in goat milk of the castor oil group are successive products of the β-oxidation of 12-OH-18:0, and the 10-oxo-16:0 and 8-oxo-14:0 are successive products of the 12-oxo-18:0 in tissues. Overall, our results indicate that ricinoleic acid is extensively metabolized in the rumen and tissues, producing mainly oxo- and hydroxy-FA that are further excreted in milk.     

Development of Quality Index Method (QIM) scheme for Acoupa weakfish (Cynoscion acoupa)

A Quality Index Method (QIM) scheme for gutted and iced Acoupa weakfish (Cynoscion acoupa) was developed and its efficiency for freshness evaluation was compared with instrumental colour analysis, microbial and chemical methods. The QIM scheme comprises sensory evaluation of 14 parameters, reaching a total sum of 23 demerit points. The evolution of Quality Index (QI) was identical in two independent storage experiments and could be represented by the equation QI = 1.3593 × days − 0.3822 (R² = 0.9614, P < 0.0001). The QIM results indicated a shelf life of 8–9 days, when the sensory quality was considered unacceptable. The storage time affected a∗ and b∗ values for fish gill and caudal fin, respectively. Psychrotrophic bacteria counts (PBC) increased at different rates during the iced storage of fish in three independent storage experiments, reaching the maximum recommended limit for marginally acceptable quality products of 10⁷ CFU/g between 6 and 14 days. The shelf life of Acoupa weakfish estimated by QIM was slightly longer than that evaluated by PBC. The rate and pattern of total volatile base nitrogen and trimethylamine production was different in fish from three independent storage experiments. The use of QIM scheme was a reliable way of assessing freshness of Acoupa weakfish.     

Detection of the adulteration of olive oils by solid phase microextraction and multidimensional gas chromatography

The presence or absence of filbertone in 21 admixtures of olive oil with virgin and refined hazelnut oils obtained using various processing techniques from different varieties and geographical origins was evaluated by solid phase microextraction and multidimensional gas chromatography (SPME–MDGC). The obtained results showed that the sensitivity achievable with the proposed procedure was enough to detect filbertone and, hence, to establish the adulteration of olive oil of different varieties with virgin hazelnut oils in percentages of up to 7%. The very low concentrations in which filbertone occurs in some refined hazelnut oils made difficult its detection in specific admixtures. In any case, the minimum adulteration level to be detected depends on the oil varieties present in the adulterated samples. In the present study, the presence of R- and S-enantiomers of filbertone could be occasionally detected in olive oils adulterated with 10–20% of refined hazelnut oil.