Termo-mehanička i senzorna svojstva pšeničnog i ražanog hleba pripremljenih sa različitim koncentracijama aditiva

The effects of different concentrations of complex additive containing emulsifiers, oxido-reductive substances and enzymes, on the rheological conditions of dough and sensory properties of three groups of bread were investigated. The dough obtained from mixed wheat and rye flours had the best initial quality and the lowest degree of protein network weakening. The best expected baking properties were shown by the white wheat flour due to the least damage of its starch. The use of the additive had an effect on the absorption of water and on the majority of S-values of all sorts of flour. The amount of additive had a significant effect on the sensory properties of wheat bread crumb texture. Also, storage duration significantly affected (p lt 0.01) the sensory properties of integral wheat bread aroma-taste and the weighted mean score. The interaction of these two factors had no significant effect on any of sensory properties of the investigated groups of bread.Primenom klasičnih reoloških metoda moguće je ispitati kvalitet brašna i njegovu pogodnost za specifične namene, uglavnom na bazi osobina proteina i skorba. Upotrebom savremenih uređaja simuliraju se procesi koji se odvijaju tokom proizvodnje hleba i dobija se niz informacija o fizičkim parametrima testa (apsorpcija vode, razvoj i stabilnost testa, mehanička i termička razgradnja proteinske mreže), stanju skroba u testu (nivo želatinizacije, amilolitička aktivnost, stabilnost pri kuvanju) uz značajno skraćen postupka ispitivanja. U ovom radu, ispitivani su efekti različitih koncentracija kombinovanog aditiva na reološka svojstva testa i senzorne osobine tri grupe hleba. Najbolji početni kvalitet i najniži stepen slabljenja proteinske mreže je uočen kod testa dobijenog iz mešavine pšeničnog i ražanog brašna. Najbolja očekivana pecivna svojstva imalo je belo pšenično brašno, zbog najmanjeg oštećenja skroba. Upotreba aditiva uticala je na apsorpciju vode i na većinu C-vrednosti svih vrsta brašna. Koncentracija aditiva imala je značajan uticaj na senzorno svojstvo teksture, tj, mrvljivost pšeničnog hleba. Vreme skladištenja je veoma značajno (p lt 0,01) uticalo na senzorna svojstava arome tj. ukusa integralnog pšeničnog hleba i statistički značajno na ponderisanu srednju vrednost ocene ovog hleba. Interakcija ova dva faktora nema statistički značajan uticaj na bilo koje od senzornih svojstava ispitivanih grupa hleba

CaO&CaSO4 and CaO&Al2(SO4)3 as Pectin Precipitants–Model of Overlapping Diffuse Layers

This work is concerned with the theoretical basis of novel sugar beet juice purification method using binary systems CaO&CaSO4 and CaO&Al2(SO4)3. The Gouy–Chapman–Stern (GCS) model of overlapping of diffuse layers of EDLs on pectin surface and that on Ca2+ and Al3+ ions, theoretically explains this method. The change of the zeta potential was used to quantitatively indicate overlapping of diffuse layers. For the experiment two model solutions of pectin (0.1 % w/w) were prepared, while the concentrations of CaO&CaSO4 and CaO&Al2(SO4)3 in the range of 50–500 g dm-3 were used. The greater decrease in the absolute value of zeta potential indicated greater overlapping of diffuse layers between pectin particles and Ca2+ and Al3+ ions and faster coagulation of pectin. The overlapping degree increased with increased concentration of these binary systems. Pectin with a greater surface charge and multivalent Al3+ from CaO&Al2(SO4), exerted a greater impact on the zeta potential. Optimal quantities of the applied binary mixtures were as follows: 256–640 mg g-1 pectin. This is much lower than CaO commonly used in the conventional process of sugar beet juice purification (about 9 g g-1 pectin)

Trading quality and breadmaking performance of wheat treated with natural zeolite and diatomaceous earth

The aim of study was to investigate the influence of naturally occurring zeolite and diatomaceous earth, as inert dusts approved for insect pest control in certified organic crop production, on trading and breadmaking quality of treated wheat. The treatments significantly reduced the trading quality of wheat which was reflected through lowering of test weight. This effect was more marked in the case of low-vitreous wheat rather than in high-vitreous one. Investigation of rheological properties of flours made from the treated wheat demonstrated that treatments with natural zeolite and diatomaceous earth at all applied doses significantly increased the water absorption, which consequently increased the bread yield. However, these changes in the flour properties were not high enough to modify the quality attributes of bread as was shown by instrumentally measuring crumb hardness and springiness as well as sensory evaluation

Comparative study on the physico-chemical, textural and thermal properties of instant porridges based on spelt and oats

Changing of food habits and increased preference for healthy meals, along with the growth of breakfast industry has increased the size of 'ready-made' and instant porridge market in Serbia. Porridges dominantly marketed are those based on oats. However, there is a growing interest of local producers to use other cereals for porridge production. Therefore, this work was aimed to estimate the porridge-making ability of spelt wheat (Triticum aestivum spp. spelta) in comparison to that of oats. The studied porridges are instant products, based on extruded spelt or oat flour. The proximate composition, hydration properties (water absorption index-WAI and water solubility index-WSI), consistency and thermal properties were determined with the aim to compare the characteristics of the porridges. In general, the spelt-based porridge had more total and insoluble fibres, proteins, minerals and less available carbohydrates in comparison to the oat porridge. The spelt porridge may be eligible to bear the nutritional claim 'high-fibre' which is advantageous for the market viability of the product. Both porridges had >20% of damaged starch due to high initial content in the flours and extrusion processing of flours, though spelt-based extrudate and porridge were significantly higher in this parameter. Oat-based extrudate and porridge were higher in resistant starch content. The consistency was similar between the porridges, although spelt tended to form slightly firmer and cohesive porridge. Spelt porridge had better hydration properties (higher WAI) which are a featured attribute for this kind of product, similarly to higher consistency values. Spelt wheat, in its extruded form, is a suitable ingredient for porridge production

Analysis of the influence and optimization of concentration of organic acids on chemical and physical properties of wheat dough using a response surface methodology and desirability function

In order to improve physical and chemical properties of dough produced from wheat flour of suboptimal quality (protein content 10.7% dry basis, dough energy 4.0 cm2), optimal doses of ascorbic and citric acid were evaluated using a response surface methodology and desirability function. The paper brings the analysis of the main effects as well as their interactions. The effect of organic acids was evident in relation to pH lowering and decrease in free thiol groups, which consequently changed the physical properties of dough (increased dough energy, extensibility and resistance). The well known oxidative effect of ascorbic acid which is manifested as increase in dough energy and resistance, was enhanced by the addition of citric acid i.e. their synergistic action. Contribution of citric acid was the donation of hydrogen ions which changed the pH, lowered the content of free -SH groups and increased protein aggregation. Ascorbic acid individually significantly increased energy (linear regression coefficient b1 = 4.010-4) but higher effect was exerted by the addition of ascorbic and citric acid mixture as seen through higher interaction regression coefficient (b12 = 0.076). Dough resistance was significantly affected only by ascorbic acid due to its oxidizing action whereas dough extensibility was affected by both acids (main effects) at all applied doses and their mixtures. The effect on dough extensibility depends on the dose of acids but resistance decreased with quadratic increase of acid doses. Second-order polynomials were used in modeling of responses (dough energy, resistance and extensibility) which showed a good fit with experimental data as shown by high values of the coefficients of determination R2 for energy, resistance and extensibility (0.953, 0.976 and 0.996, respectively). Based on F value, it could be concluded that the model gave good prediction of experimental data while p-values for all responses showed that the models were significant at significance of 90%. The obtained models were used to optimize the doses of ascorbic and citric acid in order to maximize dough energy and extensibility. Significant increase of dough energy by 4.7 times and extensibility by 1.5 times was achieved by the set of optimum conditions of 97 mg/kg citric and 100 mg/kg ascorbic acid. The obtained results are applicable in semi-industrial and industrial facilities for flour processing

Osmotic dehydration of carrot in sugar beet molasses: Mass transfer kinetics

The osmotic dehydration process of carrot in sugar beet molasses solutions (40, 60 and 80%), at three temperatures (45, 55 and 65°C) and atmospheric pressure, was studied. The main aim was to investigate the effects of immersion time, working temperature and molasses concentration on mass transfer kinetics during osmotic dehydration. The most important kinetic parameters were determined after 20, 40, 60, 90, 120, 180, 240 and 300 min of dehydration. Diffusion of water and solute was the most intensive during the first hour of the process and the maximal effect was observed during the first 3 hours of immersion. During the next two hours of dehydration, the process stagnated, which implied that the dehydration time can be limited to 3 hours

Osmotic dehydration of red cabbage in sugar beet molasses: Mass transfer kinetics

The paper describes a study of osmotic dehydration of red cabbage in sugar beet molasses of different concentrations (40, 60 and 80%) at 50°C and under atmospheric pressure. The best results were obtained at the sugar beet molasses of 80% as an osmotic medium. The most important kinetic parameters of the process were determined: water loss, solid uptake, weight reduction, normalized solid content and normalized moisture content. The kinetic parameters were determined after 1, 3 and 5 hours. Mass transfer coefficients were calculated using Hawkes and Flink's model and the results indicate that the diffusion of water and solids was the most intensive during the first three hours of dehydration

Thermo-mechanic and sensory properties of wheat and rye breads produced with varying concentration of the additive

The effects of different concentrations of the complex additive containing emulsifiers, oxido-reductive substances and enzymes, on the rheological conditions of dough, and on the sensory properties of three groups of bread were investigated. The best initial quality and the lowest degree of protein network weakening had the dough obtained from mixed wheat and rye flours. The best expected baking properties were shown by the white wheat flour due to the least damage of its starch. The use of the additive has an effect on the absorption of water and on the majority of C-values of all sorts of flour. The amount of additive had a significant effect on the sensory properties of wheat bread crumb texture. Also, storage duration significantly affected (p <0.01) the sensory properties of integral wheat bread aroma-taste and the weighted mean score. The interaction of these two factors had no significant effect on any of sensory properties of the investigated groups of bread

The comparison of techniques and methods for L-ascorbic acid determination in the fruits

Vitamin C is an essential vitamin for human nutrition; with the L-ascorbic acid (AA) being the active form of vitamin C. Hence, determination of the L-ascorbic acid in the natural and processed foods is very important. In the past, plenty of methods based on the reversible redox reaction of AA oxidation/DHA reduction were developed. Because of L-ascorbic acid instability in aqueous solutions, it is useful to analyze various types of extraction. The aim of this study is to compare three different methods and three different extractants for the L-ascorbic acid determination. Fruits (kiwi, lemon, orange, and grapefruit) were purchased from a local market. The L-ascorbic acid in these four samples was determined by the three different methods: the AOAC, the HPLC method with three different types of extractions, and the colorimetric method using ascorbate-oxidase. For the HPLC measurements, one part of the fruits was extracted with distilled water, the second with potassium hydrogen phosphate, and the third with 3% meta-phosphoric acid (MPA) in 8% acetic acid. The HPLC measurements of each sample were repeated three times, the AOAC titration was repeated five times, and in the calorimetric method three measurements were performed. The results were statistically evaluated related to sample basis. Statistical analysis shows that there is a significant difference between the results for all three methods of extraction for all samples, except for the grapefruit sample where no significant difference was observed between the results obtained after the buffer extraction (E2) and the metaphosphoric acid in acetic acid extraction (E3). Discriminative analysis for the HPLC determinations proves that there is a clear difference and defined border between the samples in relation to the methods of extraction during the HPLC determination