Authors:J. Lénárt, T. Szigedi, M. Dernovics, and M. Fodor
Fourier transform near infrared spectroscopy (FT-NIR) has been developed for determining the fat and protein contents of hard, semi-hard and processed cheeses. Multivariate calibration models were carried out by partial least squares (PLS) regression. The diffuse reflection spectra of different type of lyophilized cheeses were measured by FT-NIR analyser in the 800–2500 nm spectral range. The calibration set of 62 samples were validated by leave-oneout cross-validation and by prediction set of 31 samples. The optimal result for fat content (root mean square error of cross-validation (RMSECV)=1.0; R2=99.1%, PLS factor= 6) was obtained when the spectra were preprocessed by first derivation (FD) combined with multiplicative scatter correction (MSC) and smoothing. The optimal result for protein content (RMSECV=1.4, R2=97.2%, PLS factor=6) was observed when the first derivation combined with straight line subtraction (SLS) and smoothing spectral preprocessing method was applied.
Authors:I. Szedljak, K. Szántai-Köhegyi, and J. Kosáry
The changes in the activity of enzyme polyphenol oxidase, the concentration of total soluble phenolic compounds and soluble protein content in different tobacco cultivars (Virginia and Burley) during cultivation, then in a combined curing model system were studied. The latter was a special combination of air-curing and flue-curing methods followed by a long fermentation period to optimize the treatment of tobacco plants used both as protein sources and starting materials in tobacco industry. The results suggest that a cultivation period of 13–14 weeks could be better for tobacco plants as protein sources, however, for starting materials for industrial use 16–17 weeks are optimal. It was found a four-week curing period could be the best for two tobacco cultivars (Virginia and Burley) in the case of using them both as protein sources and starting materials in tobacco industry.
Authors:D. Hadanich, J. Perédi, M. Juhász-Román, and B. Nagy
In the microflora of sunflower seeds stored in domestic stores the,
species dominate, while those of
Penicillium, Trichoderma, Stemphylium
spp. are present in lower numbers. During model tests (cca 20% seed moisture content, 25 °C, 4 weeks storage) the
species were almost completely eliminated and on the seeds mainly
species, characteristic of stores, propagated. The moulds significantly deteriorated the quality of the seed and that of the produced oil and meal (reproductive ability, germinating power, oil content, lipoxygenase enzyme activity, acid value, peroxide value, fatty acid composition, UV absorbance, colour, sensorial properties, as well as the protein content, amino acid composition, colour and the smell of the meal), but no aflatoxin production occurred. The findings offer a comprehensive picture on the multiple destructive effects of incorrect storage.
The effect of heat induced changes on the immunoreactivity of a-lactalbumin (a-la) in whey was evaluated. Whey and acidified a-la solutions were heated for various times at temperatures between 60 and 100 °C. After heating, the samples were clarified and the protein content (by Bradford's method), the quantity of a-la (by FPLC method) and the immune response to an anti a-la probe were determined. The samples heated at 80 °C were characterized by the highest a-la immunoreactivity properties. Raising temperature up to 90 °C and 100 °C caused a marked decrease in a-la immunoreactivity. As was found by FPLC method in the samples heated at 60 and 65 °C, a-la content changes were not statistically significant. A gradual decrease in the content of a-la was observed with increased temperature and duration of heating.
Authors:C. Capetillo Leala, L. Ancona Méndez, C. Sandoval Castro, and G. Cetz Zapata
from Yucatan State, Mexico was compared with a local variety of
, in terms of chemical composition and amino acid profile. No differences were found (P=0.55) in crude protein content of
(20.2±0.15 vs. 20.3±0.16 g/100 g DM., respectively).
had a lower fiber and fat content (P<0.05). No difference was found in ash content (P>0.05).
has a higher proportion (P<0.05) of valine, isoleucine, phenylalanine, aspartate and alanine while
had higher proportion (P<0.05) of proline and glutamate, no difference was found in the remaining amino acids. Both species had a high proportion of aspartate and glutamate. In general, the human amino acid requirements for adults are satisfied, however, leucine and lysine might become limiting. It was concluded that
can be included in human diet in similar fashion as
Authors:W. Obuchowski, A. Makowska, S. Mildner-Szkudlarz, A. Szwengiel, M. Majcher, and M. Remiszewski
The objective of the study was to determine the effect of grain preparation technology, extrusion cooking conditions, and triticale cultivars on physico-chemical properties of crisp bread. Triticale cultivars used in the experiments differed in protein content, starch content, amylolytic activity, and viscosimetric properties. The type of the twinscrew extruder used has an effect on starch degradation, phenolic contents, and antioxidant activity of the product, but a greater effect on those characteristics is found for grain scouring prior to extrusion. All factors had an effect on volatile compound amounts in crisp bread, but the direction and range of these changes were random in character. Results of this study show that triticale grain can be useful raw material for the production of flat bread.
Authors:Tanja Pfeiffer, Ivna Štolfa, M. Žanić, N. Pavičić, Vera Cesar, and H. Lepeduš
Olive is one of the most important cultivated Mediterranean plants. In order to determine the differences in frost resistance of two, two-year-old olive cultivars (Olea europaea cv. Leccino and cv. Oblica) growing on different types of nutrient substrates (soil and coconut fibres), the trees were exposed to low temperature (−5 °C) in the dark. It was shown that low temperature caused an increase in H2O2 concentration, level of lipid peroxidation and carbonyl protein content in both cultivars and on both nutrient substrates, respectively. The CAT and APX activities significantly varied depending on the cultivar, the nutrient substrate type and the time of exposure to low temperature. Cv. Oblica and cv. Leccino growing on coconut fibres showed a better antioxidative response to low temperature probably due to the higher nitrogen and phosphorus concentration established in this type of nutrient substrate. That positive antioxidative response determined on coconut fibres was more pronounced in leaves of cv. Leccino.
Authors:A. Bittsánszky, V. Rai Ravishankar, and G. Oros
Okra seedlings tolerated soil-borne Rhizoctonia infection in strain dependent manner. No connection was revealed between pathogenicity of strains and their origin or taxonomic position. However, the okra proved to be susceptible to strains highly pathogenic to other host plants as well. R. zeae, a species new to European flora, was as aggressive to okra as the most potent R. solani strains. The effect of Rhizoctonia infection was more prominent on mass accumulation in hypocotyls than in cotyledons. The protein content and glutathione S-transferase activity increased in parallel with the evolution of disease syndrome. Metalaxyl, an acetanilide type systemic antioomycete fungicide induced glutathione S-transferase activity in cotyledons with 24 hours a phase, and this induction was more outstanding in symptomless seedlings grown in Rhizoctonia infested soil. It might be concluded, that the stress response of plants in tolerant host/parasite pair takes effect at higher level than in susceptible relationships.
Many wheat species and cultivars, independent of genetic markers of hardness, can produce grain with a vitreous, mealy or mixed appearance. This study analyzed selected chemical and physical differences between kernels with a vitreous and mealy appearance, hand-picked from grain of four winter wheat cultivars cultivated in Poland. Separated fractions were examined for protein content and composition, friabilin presence, carotenoids and total phenolic compounds content, specific kernel density, hardness, as well as kernel surface color. It was found that the ratio of vitreous kernels in the cultivars ranged from 39.18% to 76.28%. Vitreous kernels were darker, slightly heavier and harder than mealy kernels. Additionally, these kernels were more abundant in proteins (an average increase of 2.13%, with variation among cultivars from 0.71% to 2.89%). This type of kernels was also richer in phenolic compounds (on average by 4.02%) and less abundant in carotenoids (on average by 4.53%). Mealy (softer) kernels fractured to a finer flour.
Authors:J. Knorr, M. Schiekel, W. Franke, and F. Focke
Determination of protein content in food materials is usually done by analyzing the nitrogen amount by wet chemical Kjeldahl method. An improved accuracy accompanied by smaller analyzing intervals can be achieved using nondestructive neutron activation. Analyses have been performed using 14 MeV neutrons to determine the content of N and P in single wheat corns. Irradiation parameters have been optimized to prevent serious radiation damage in the grains. About 200 single corns have been investigated with total net weights ranging from 30 to 70 mg. The tested arrangement allows determination of nitrogen amount in a single corn down to 0.3 mg with an accuracy of better than 4%. Mean nitrogen concentrations in the range from 9 to 19% per corn have been detected.