Optimization of the enzymatic synthesis of fructo-oligosaccharides using fructosyltransferase from aspergillus aculeatus

The obvious benefits of employing prebiotics as functional components in many food and feed products have resulted in higher demand for their industrial production, necessitating the development of more efficient and cost-effective manufacturing procedures. As a result, the goal of this study was to synthesize confirmed prebiotics, namely fructo-oligosaccharides (FOS), using sucrose as a substrate, since it allows the synthesis of oligosaccharides with lower polymerization degree, and consequently, a more pronounced prebiotic effect. Due to its availability, low market price, and high stability under industrial conditions, a commercial enzymatic mixture, Pectinex® Ultra SP-L, is used as a source of enzyme – fructosyltransferase (FTase). By optimizing reaction conditions such as pH, temperature, enzyme and substrate concentrations, as well as the duration of the process, the composition of the FOS mixture can be adjusted to fit the potential applications. It was found that by performing the reaction in an aqueous medium (pH 7), at a temperature of 50 °C using an enzyme concentration of 1% (v/v) and any sucrose concentration in the range of 200-700 g/L, it was possible to achieve maximum FOS yield of 60% of total carbohydrates within a 24 h. The produced syrup with a high content of FOS can be further used as an adequate food additive, or else, optimized proceses should be used for transformation of various food products (such as juices, jams, fillings, candies, cakes, etc.) in which sucrose dominates, creating products with lower caloric and higher functional value.

Arsenic content and phenolic compounds in parsley (Petroselinum crispum (Mill.) Fuss) and celery (Apium graveolens L.) cultivated in Vojvodina region, Serbia

Randomly collected samples of parsley and celery from different localities were analyzed to determine their quality based on arsenic concentrations, phenolic constituents and the antioxidant capacity of their edible parts. Arsenic concentrations were found in the range: parsley root (0.16 μg/g d.m.) < celery root (0.19 μg/g d.m.) < parsley leaf (0.35 μg/g d.m.) < celery leaf (0.45 μg/g d.m.). Total phenolic contents in roots were similar in both species and varied significantly depending on the cultivation site: 5.03-9.18 mg eqGA/g DE in parsley and 5.04-8.50 mg eqGA/g DE in celery. Lower total flavonoids content was recorded in celery. Among the phenolic acids, ferulic, chlorogenic and several cinnamic acids dominated. Apigenin and its glucosides dominated among flavonoids. Based on the principal component analysis (PCA) it can be concluded that the As content varied depending on the geographical origin of the samples. Also, phenolic compounds showed a significant contribution on PCA clustirng, indicating that cultivation site has a clear significant impact on the metabolites profile, while As content in plants did not significantly affect phenolic compound profile.

EFFECTS OF ASCORBIC ACID AND SUGAR ON PHYSICAL, TEXTURAL AND SENSORY PROPERTIES OF COMPOSITE BREADS

The present study was carried out to demonstrate the combined effects of different maize flour, ascorbic acid and sugar on the physical, textural and sensory properties of composite breads. The composite flour was prepared using 70% of wheat flour and 30% of flour obtained from grain of differently coloured maize - light blue, blue, red and yellow maize flour. Chemical characterization of composite flours made with four different types of maize was also assessed. Furthermore, the content of total phenolics, flavonoids, anthocyanins, phenolic acids and antioxidant capacity in composite flours was determined. The total of 12 breads that were prepared, four of which were control composite breads, four breads with ascorbic acid, and four were breads with ascorbic acid and sugar. The content of total phenolic compounds showed clear differences among all composite flours. The anthocyanins content determined in composite flours was in the following descending order: blue>red>light blue, while in the yellow maize composite flour anthocyanins were not detected. The results showed that the addition of AsA (0.025%) and sugar (5%) negatively affected the volume as well as the specific volume of composite wheat-maize breads. The texture analysis showed that the addition of AsA in amount of 0.025% had no impact on springiness, cohesiveness and resilience of bread crumb, while it increased crumb hardness. However, composite breads made with AsA and AsA and sugar showed a more compact structure, with a larger number of cells and smaller mean cell areas. Bread samples with AsA and sugar in the tested doses had the lowest springiness, which is indicative of brittleness and reflects the tendency of the bread to crumble when slicing. Results of the sensory evaluation revealed that the AsA and sugar addition had a generally positive effect on the investigated sensory attributes.

Determination of Protein Oxidation in Aquaculture Feed

The aim of this research was to develop reliable, easy-to-perform and cheap method for measuring protein oxidation in complex samples such as aquaculture feed within various protein sources. For that purpose modified 2,4-dinitrophenylhydrazyne (DNPH)-based method for quantification of protein carbonyls was employed, while the method modification was consisted of using different solutions for the extraction, time of protein extraction and concentration of trichloracetic acid (TCA) for protein precipitation. It was found that extraction during night, higher TCA concentration and the use of 0.5 M KCl extraction solution resulted in the highest protein amount measured by Lowry method and 280 nm protein estimation. On the other hand, the lowest protein yield was obtained by using distillated water for the extraction. Furthermore, the lowest amount of protein carbonyls was in the case when extraction was performed with distilled water (DW), while the highest content of protein carbonyls were reached with 0.15 M KCl and 0.5 M KCl extraction solutions. It was observed that the amount of carbonyls compounds were increasing during storage under accelerated conditions, and in comparison to the original (unmodified) method, the modified method for measuring protein oxidation resulted in the higher amount of carbonyls during the all points of storage.

Influence of Moisture and Temperature on the Thermal Properties of Jack Bean Seeds (Canavalia ensiformis)

The thermal properties (specific heat capacity, thermal conductivity, and thermal diffusivity) of jack bean seed (Canavalia ensiformis) were determined for usage in designing the equipment necessary for thermal processes. These thermal properties were determined at 5, 10, 15, 20, and 25 % moisture contents (wb) and temperatures at 30, 40, and 50oC using the KD2 Pro thermal analyzer. Results showed that the specific heat capacity ranged from 1.55 to 2.47 kJ/kgK, 1.26 to 1.84 kJ/kgK and 1.32 to 1.99 kJ/kgK; thermal conductivity 0.21 to 0.47 W/mK, 0.34 to 0.52 W/mK, and 0.26 to 0.60 W/mK and thermal diffusivity 0.25 to 0.41 x 10-7 m²/s, 0.32 to 0.57 x 10-7 m²/s, and 0.32 to 0.60 x 10-7 m²/s at 30, 40, and 50°C respectively for the moisture ranges studied. The temperature and moisture content effect were not significant (p>0.05) with specific heat and thermal diffusivity but significant (p<0.05) with thermal conductivity in third-order polynomial. A non-linear relationship was established between the three thermal properties and moisture content within the studied temperature range. The resulting regression models for the thermal properties gave a high coefficient of determinations (R2 ≥ 0.7995) which implies that they can be used to describe the relationships between temperature, moisture, and thermal properties of jack bean seeds.

ATTITUDES OF SERBIAN CONSUMERS TOWARDS DIFFERENT PEPPER FRUITS

Pepper (Capsicum annuum L.) is one of the major vegetable species in the world. In Balkan cuisines, as well as in Serbia, pepper has a very diverse use. Knowledge about consumers habits and preferences is of great importance for a breeding process as well as in the market-orientated production. Because of the lack of information about consumers preferences towards pepper types, in the Serbian market, the present research was conducted. Four hundred and two participants, classified into groups, according to gender, age and education, answered the survey questions. According to this research, the most preferred pepper type in Serbia is kapia, while the bell pepper is the second chosen type. Also, obtained results showed that the most favourite colour of pepper fruit is red. There is a tendency in higher importance of fruit type than fruit colour. The highest percentage of hot pepper consumers prefer medium hot peppers. The obtained trend shows that women generally prefer less spicy pepper fruits than men.

FOOD PRODUCTS PLACEMENT DURING COVID-19 PANDEMIC

The COVID-19 pandemic has entirely changed the patterns of behavior in the market. Physical distance, quarantine measures, safety and security protocols, and shortages along the entire supply chain, have particularly affected the placement of food products. In this regard, the paper aims to define the impact of various indicators on the placement of food products during the COVID-19 pandemic. An empirical study was conducted on a sample of 248 final consumers. The analysis was performed specifically for four groups of essential food products in a pandemic: meat and meat products, fruit and vegetables, milk and dairy products, cereals, and cereal products. The results showed a statistically significant impact of indicators such as safety and security standards, hygiene, price, product freshness, nutritional composition, chain transparency, and product quality. The impact of these indicators differs significantly depending on the analyzed product group. The obtained results indicate to the supply chain management which negative impacts need to be minimized to ensure timely placement of food products and more efficiently meet the needs of final consumers in a pandemic. Guidelines for future research are listed in the paper.

VITAMIN C, TOTAL PHENOLS AND ANTIOXIDATIVE ACTIVITY OF ORGANICALLY GROWN RED BEETROOT (BETA VULGARIS SSP. RUBRA) AND EFFECT OF PROCESSING

The demand for organic food is rising since consumers want food from reliable, highest quality sources originating from the environment, undisturbed by cultivation and processing. It is necessary to determine to what extent there is a scientific basis for the claims that organic food is of high quality. In this study, beetroot from an organic production system originating from 6 certified organic food producers from different geographic locations was examined. The organic beetroot samples were processed by pasteurization at 700 C and 900 C into beet juice or by drying at 550 C. The following samples were tested and compared: fresh beetroot, pasteurized beet juice and dried beetroot slices. The concentration of vitamin C, level of total phenol compounds (TPC) and antioxidative activity (TAA) in beetroot were influenced by the geographic origin and the applied processing method. The highest degradation for all analysed parameters was found in the samples treated by drying or pasteurisation at 90ºC. The lowest losses of studied phytochemical components were observed during juice pasteurisation at 700C. The correlation coefficient between TPC and TAA was high and significant (r2 = 0.966).

EFFECT OF COOKING ON THE CONTENT OF CAROTENOIDS AND TOCOPHEROLS IN SWEET CORN

Taste and nutritional value make sweet corn a valued plant and an important component of the human diet worldwide. Kernel nutritive composition of sweet corn has been reported in various papers, but a description of carotenoid and tocopherols profile, especially after cooking is scarce. Therefore, the present study was carried out to compare the carotenoid and tocopherol content in sweet corn before and after cooking. Contents of β-carotene, lutein+zeaxanthin and tocopherols (δ-T, β+γ-T, α-T) in the kernels of twelve sweet corn hybrids were determined by High-Performance Liquid Chromatography (HPLC) and were expressed as the mean value of three independent measurements. Both genotype and cooking affected the content of the carotenoids and tocopherols in the kernel. The highest content of total carotenoids before and after cooking was found in hybrid ZP486/1su (27.77/45.28 µg/g) whereas the lowest content was in hybrid ZP 355su (10.27 µg/g) before cooking i.e. in hybrid ZP 347su (24.55 µg/g) after cooking. The cooking resulted in a significant increase in the content of total carotenoids and tocopherols, lutein+zeaxanthin, and β-carotene in all hybrids, except the ZP504su in which the β-carotene content decreased. An increase in α-tocopherol after cooking was observed in hybrids ZP485/1su and ZP484/1su, while a decrease was in hybrids ZP481/1su, ZP486/1su and ZP477/2su. The results showed that increasing micronutrient content is genotype-dependent. This study confirmed that cooking increases the nutritional value of sweet corn and gives it additional value in terms of functional food.

ARE ORGANIC PLANT PRODUCTS OF MORE IMPROVED CHEMICAL COMPOSITION THAN CONVENTIONAL ONES?

Considering negative effects of conventional agricultural production, organic food production is a sustainable approach to the production, which preserves the environment and protects human health. Organic products are products of high quality, without residues of pesticides and other harmful chemicals. Through the review of literature data, authors of this paper presented a comparison of chemical compositions of organically and conventionally grown plants and their products. Dry matter, nitrates, sugars, vitamins, macro- and micro-elements, as well as, secondary metabolites have been singled out. According to obtained data, organic products contain more dry matter, significantly less nitrates, less proteins and a higher proportion of amino acids, more sugars, vitamin C, numerous macro- and micro-elements (particularly Fe, Mg and P), more polyphenols and they have higher total antioxidant capacity than conventional products. Although many authors have been dealing for many years with the comparison of the nutritional composition of organic and conventional food products, a clear consensus that organic products have the improved chemical composition compared to conventional products has not been reached yet, i.e. the answers are ambivalent. Therefore, further long-term studies are necessary in order to clarify the existing doubts.