Potravinarstvo Slovak Journal of Food Sciences
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The evaluation of selected qualitative parameters of sweet potato (Ipomoea batatas L.) in dependence on its cultivar
Get PDFThe sweet potato (Ipomoea batatas L.) is relatively known vegetable species, but it is grown only on small area in the Middle European region. Its cultivars are characterized by different colour of tuber flesh which can be white, beige, yellow, orange and purple. The aim of this study was to determine and compare selected qualitative parameters of tubers (total carotenoids, vitamin C and total soluble solids) among orange, white and purple sweet potato cultivars. The field experiments were established at Slovak University of Agriculture in Nitra in 2016 and 2017. Sweet potatoes were grown by hillock system with using of black non-woven textile for soil mulching. The tuber harvest was realised on the 6th October 2016 and 13rd September 2017. The highest content of total carotenoids was found in orange sweet potato cultivars (78.47 - 122.89 mg.kg-1 fresh weight) and its values were multiple-fold higher in comparison with purple (4.22 mg.kg-1 f. w.) and white (10.71 mg.kg-1 f. w.) cultivars. Orange cultivars were also richer source of vitamin C (246.31 - 325.99 mg.kg-1 f. w.) compared to white (179.66 mg.kg-1 f. w.) and purple (187.75 mg.kg-1 f. w.) cultivars of sweet potatoes. The total soluble solids, expressing mainly sugar content, was higher in purple (10.13 °BRIX) cultivar of sweet potatoes, followed by cultivars with orange (8.52 - 9.72 °BRIX) and white (5.57 °BRIX) tuber flesh. Obtained results showed the significant effect of cultivar, characterized by different tuber flesh colour, on the composition and contribution of sweet potatoes for human health.
Tin compounds in food - their distribution and determination
Get PDFThe aim of this work was optimization of the methods of trace- and ultratrace analysis, such as ICP-OES, ETA-AAS for charting the resources of individual forms of tin in foodstuffs. Increase of the sensitivity of the method of ICP-OES was achieved using the techniques of generation of hydrides, which was also optimized. Based on the information available on the occurrence of the different forms of tin, it appears that many of these organometallic compounds are contained in marine animals; attention has mainly focused on organisms such as marine fish, crustaceans, molluscs and algae. Tin compounds of predominantly inorganic origin can be found in foods and beverages which are packed in cans with a protective tin coating, too. The above mentioned methods have been applied to the analysis of selected beverages with low content of tin such as Coca Cola, Sprite, Fanta, Gambrinus 10°, PowerKing, and milk in the cans. Furthermore samples of animal origin as Sardines in oil, and Hunter's salami were examined, too. Prior to the determination of tin, samples need to be appropriately modified or analysed. Decomposition of the samples was done in the microwave system. Low pressure ion exchange chromatography with on-line detection of ICP-OES was used for separation of inorganic tin compounds. Separation of organically bound tin compounds was performed by HPLC on a column of ACE C-18, 3 µm, 15 cm × 1.0 mm with off-line detection by ETA-AAS. All of the above forms of tin compounds can be separated with this column. Due to the improvement in the detection of organically bounded tin, HPLC with identical ACE C-18 column coupled online for example with ICP-MS or spectrofluorimetry could be recommended
Expression pattern of thaumatin in the selected red varieties of Vitis vinifera, L.
Get PDFVitis vinifera L. is a specie that is adapted to a very variable range of climates, from cold up to the desert one, but especially it grows in the temperate Mediterranean regions and continental areas of Europe. Grape is a widespread consumed fruit as well as processed to musts, juices or wine. The health beneficial effects of grapes and wine are very well known due to their high nutritional value and unique phytochemical composition. Despite many health protective and beneficial effects of Vitis vinifera, a part of population suffer to allergic reactions to this fruit. Allergens of wine and grapes are: endochitinases, lipid-transfer protein and thaumatin. Thaumatin is a protein having a sweet taste belonging to the PR5-like proteins. These proteins are very difersified in their functions and were described to be involved in stress responses and fruit ripening, but are expressed in healthy grape fruits in a constitutive manner and needn´t to be expressed only as a answer to the stress. Thaumatin is a minor allergen in grape, but belonging to the suspected panallergens relevant to the food cross-allergy induction, its importance is quite high. Another importance of this protein is a technological one, as reported to aggregate in wine to form a visible haze unless removed prior to bottling. In this study, expression of thaumatin-like allergen was analysed in the grapes of selected varieties. Grapes of four red varieties of Vitis vinifera, L. were obtained in the season 2017 in the Sabo winery that belongs to the Malokarpatská wine region. Fresh maturated grapes of varieties Alibernet, Cabernet Sauvignon , Frankovka modrá and Dornfelder were analysed. Expression changes of thaumatin was calculated by delta delta Ct method. Dornfelder was found as to have the lowest activity in thaumatin-like gene activity, mainly when comparing to the Cabernet Sauvignon and Frankovka modrá. Alibernet, on the other side, has the expression level of thaumatin very similar when comparing to the Cabernet Sauvignon and Frankovka modrá
Is edible insect as a novel food digestible?
Get PDFThis work deals with the digestibility of a selected species of edible insect - mealworm (larvae) as novel food in dependency on its culinary treatment. The aim of this work was to find suitable thermic culinary treatment of mealworm larvae considering its optimum digestibility by human. The digestibility of materials from whole insect and extracted nitrogenous substances was determined using three different culinary treatments - without culinary treatment (freshly killed), dried insect and roasted insect. The digestibility was determined by gravimetric in vitro method using pepsin and pancreatin enzymes and their combination. The total nitrogen content of the insect samples was determined by the Kjeldahl method. The digestibility of the whole homogenized larvae using the combination of pepsin and pancreatin enzymes, thus simulating human digestion in-vitro, ranged from 81% for roasted specimens to 91.5% for culinary unprocessed insect. Similarly, the digestibility of nitrogenous substances of homogenized insect samples using this combination of enzymes ranged from 24.2% for roasted specimens to 80.2% for culinary unprocessed samples. The work showed the dependence of the digestibility of the mealworm larvae on the culinary treatment - the increasing heat load of the sample reduced the digestibility. Furthermore, it proved the effect of the digestive enzyme on the digestibility of the insect sample
Biogenic amines in smear ripened cheeses
Get PDFCheeses belong to high protein foods in which enzymatic and microbial activities form amino acids, which are then converted into biogenic amines (BAs) by the activity of bacterial decarboxylases. The most important conditions for BA formation include the presence of microorganisms, the availability of substrate, temperature and storage period, water activity, salt concentration, and the hygiene of the manufacturing process. Tyramine, histamine, 2-phenylethylamine, tryptamine, cadaverine, putrescine, spermidine and spermine were detected in smear ripened cheeses stored in different temperature regimes. The highest (p < 0.05) total BA content was found when storing the cheeses at the end of BBD (best before date) after 35 days in storage regime (A) or (C). During storage in regime (B), the total BA content (p < 0.05) after 49 days of storage was higher than on the production date (B/0). During storage, the tyramine content in regime (B) did not change (p > 0.05), while in the temperature regimes (A) and (C), the highest levels of tyramine and putrescine content were recorded in cheeses at the end of BBD after 35 days ripening. The content of polyamines in cheeses was higher (p < 0.05) at the end of storage than at the beginning, in all temperature regimes
Influence of technological processing on lipid-lowering activity of substances containing in porcine hearts and aortas
Get PDFEdible by-products are a good source of nutrients and bioactive substances and could be used as functional ingredients or for biopeptides production natively contained in raw materials. A wide range of peptides are also formed during the enzymatic hydrolysis or food processing. The comparative results of the effectiveness of isolated certain protein and peptide fractions by ultrafiltration with the same natively presented in raw tissues, as well as the influence of heat treatment on biological activity of origin active substances are presented. The model of rat alimentary hyperlipidemia was developed by adding cholesterol and fat to the standard diet and vitamin D2 injection per os. Serum lipid profile was determined on automatic analyzer BioChem FC-360. Dynamic of changes in serum lipid profile was assessed as corresponding control group medium results in ratio to certain rat data. Two-dimensional electrophoresis (2DE) was performed according to the method of O’Farrell with isoelectric focusing in ampholine pH gradient (IEF-PAGE) with following identification by MALDI-TOF MS and MS/MS mass spectrometry. Consumption of native pig aorta and pig heart during 14th days led to normalization of lipid profile in serum of hyperlipidemic rats, while low molecular weight (LMUF, MW <5 kDa) and medium molecular weight (MMUF, MW = 5 – 30 kDa) ultrafiltrates of pig aorta extract did not strongly influenced on level of triglicerides and, on contrary, elevated high density cholesterol. Consumption of developed product by hyperlipidemic rats during 28th days did not lead to significant changes in serum lipid profile, while on 42nd day all ratios reached ones in group, which were treated with native raw material or isolated active fractions. The stability of developed product was confirmed by proteomic studies. Obtained results open prospects to modernization the technology, presumably use as a matrix dietary meat (e.g. poultry) with incorporated active identified components
Comparative study of some bioactive compounds and their antioxidant activity of some berry types
Get PDFBerries are wealthy in bioactive compounds like phenolic compounds and flavonoids that are deemed antioxidants and are great important to health. This research was performed to examine, recognize and compare bioactive compounds in certain types of berries and their antioxidant activity. The data show that blue berry, black berry and Egyptian black mulberry contain the highest content of most bioactive compounds such as phenolic compounds, flavonoids and tannins, while long mulberry and red currant berry have the lowest content for most of these compounds. They therefore, contain the highest value of antioxidant activity. The chemical composition of the berries varies depending on cultivar, variety, location of growth, environmental conditions and harvest time, as well as post-harvest treatments therefore the composition differed from berry fruit to another. Thus, berry fruits are very useful in nutrition to protect the body from many diseases because of its containment of these compounds, which act as free radicals scavenger that harm the body and thus rid the body of many harmful toxins
The impact of freezing methods on functional and technological properties of semi-finished rabbit meat products
Get PDFDuring storage meat and semi-finished meat products, the decisive factor is the correct implementation of freezing process, because the physical, histological, biochemical, microbiological changes that occur at this time, affect the final quality of product after defrosting procedure. Accordingly, studies of the impact of traditional and shock-freezing methods on functional and technological properties of semi-finished rabbit meat products represent scientific and practical interest. The effect of freezing temperature of natural and minced semi-finished rabbit meat products on the duration of cold treatment process has been studied, and the regression equations of their relationships have been obtained and regression curves have been constructed. It has been established that unlike traditional method, by the type of semi-finished products, the duration of cold treatment by shock-freezing method is 3 - 3.5 times shorter. The optimal freezing parameters have also been selected. It has been shown that the use of shock-freezing method contributes to the reduction of mass losses of semi-finished rabbit meat products, and by the type of semi-finished products, they are 5 - 5.3 lower as compared to traditional method of freezing. The determination of functional properties has revealed that shock-freezing allows for increasing water binding capacity-by 23.2 - 31.9%, water holding capacity-by 20 - 25% and pH by 6.7 - 10.4%. There have been studied microbiological indicators of frozen semi-finished products and their changes during the storage process. It has been established that they meet the safety and hygiene requirements for meat products. The full results obtained indicate the advantage of shock-freezing method as compared to traditional methods, as well as point to the appropriateness of its use when selecting the cold treatment modes for semi-finished rabbit meat products
Rheological properties of tomato ketchup
Get PDFThe objective of this paper was to determine the rheological properties especially shear stress and apparent viscosity vs. shear strain rate, and density of commercially available but also homemade tomato ketchup. The effect of tomato content of density and apparent viscosity of tomato ketchup was also described. Shear stress and apparent viscosity were observed in shear strain rates range from 0.1 s-1 up to 68 s-1. All measurements were carried out at a constant temperature of 22 °C. Experimental results were modeled using a power-law (also known as Ostwald-de Waele) model (R2 ranged from 0.9508 up to 0.9991). The flow behaviour of all measured tomato ketchup samples exhibited non-Newtonian pseudoplastic (shear thinning) behavior where the flow index (n) showed values between 0 and 1. Flow index (n) and consistency coefficient (K) can be used especially in numerical simulation of the flow behaviour of pseudoplastic (shear thinning) liquids
Identification of lard on grilled beef sausage product and steamed beef sausage product using fourier transform infrared (FTIR) spectroscopy with chemometric combination
Get PDFMany issues are spreading about the use of lard in food, one of it is sausage. Sausage is one of the processed foods which are prone of containing pork. In Indonesia, grilled and steamed sausages are popular for children and adults. One of the method which is developed to analyze fat in grilled and steamed sausage products was FTIR spectrophotometry combined with chemometrics. This research aims to develop an analysis method using FTIR spectrophotometry combined with chemometrics to analyze lard content in grilled and steamed beef sausage. Reference sausage made from a mixture of pork and beef. This research was designed by making each 7 concentrations variants of pork and steamed sausage samples (100%, 75%, 65%, 50%, 35%, 25% and 0%). Five samples from market were taken from various beef sausage traders. The fat extraction used n-hexane solvent at the temperature of 70 °C for 5 hours. The extracted fat was analyzed by FTIR spectrophotometry combined with chemometrics. The results of spectrum were analyzed using Horizon MBTM to obtain optimum wave number of steamed sausages in the range of 1000 – 791 cm-1 and grilled sausages in the range of1070 – 796 cm-1. The analysis of steamed sausage with Partial Least Square (PLS) is obtained the equation y = 0.9977x + 0.1166; and the value of R2 0.9977; RMSEC 1.22%; RMSEP 0.22%; and RMSECV 1.26%. The PLS analysis of grilled sausage is obtained the equation y = 0.9972x + 0.1379; and the value of R2 0.9972; RMSEC 1.27%; RMSEP 0.42%; and RMSECV 0.18%. The conclusion of this research is that the FTIR method combined with chemometrics is the proper method for analyzing fat in sausages. The analysis result using Principle Component Analysis (PCA) was obtained from 3 of 5 samples in the market which had the similar physicochemical properties of lard sausage