Band 13, Heft 3 -

The effect of different sugar types on the sensory characteristics of Maillard reaction products (MRPs) obtained from sunflower protein hydrolysates was evaluated. MRPs were prepared at 120 °C for a time of 2 h and a pH of 7.4. Results showed that the browning intensity, colour development and free and total amino acids of MRPs were highly affected by the sugar types. Peptide-xylose-cysteine (PXC) were more dark-brown in colour with lower free and total amino acid (FAA and TAA) content compared to the other MRPs. However, PXC showed great mouthfulness and continuity taste with stronger meat-like flavour and umami taste compared to MRPs. MRPs from hexose except PGaC, showed acceptable mouthfulness and continuity taste while PLC and PMC and PGaC showed higher caramel-like flavour and bitter taste. Furthermore, pentose sugars (xylose) were the great precursor of sulphur-containing compounds. It could be concluded that sunflower peptides, xylose, cysteine model system could be a good precursor of flavour enhancers.

Purification, characterization, in vitro antioxidant and antitumour activities of polysaccharides from apple peel pomace obtained by pre-pressing separation were investigated. Apple peel polysaccharides (APP) were obtained by water extraction and ethanol precipitation. They were further purified by chromatography of Cellulose DEAE-52 and Sephadex G-150 to obtain three fractions (APP-1, APP-2 and APP-3). Both GC-MS and HPLC analysis showed that galactose and arabinose were two main components in the three fractions with an average molecular weight of 197 kDa, 395 kDa and 303 kDa, respectively. Uronic acids were only presented in APP-2 and APP-3, which were further confirmed by Fourier transform infrared spectroscopy. Besides, the results showed that the antioxidant activity measured by ferric-reducing power and scavenging of O 2 •− , DPPH • and OH • and the antitumour activity examined by HepG2 cells were connected with the content of uronic acids. These findings provide scientific basis for comprehensive utilization of apple peel pomace.

Enzymatic hydrolysis of flaxseed protein (FP) was carried out using trypsin in order to obtain flaxseed protein hydrolysates possessing better antioxidative property and modified rheological properties. The antioxidative properties of hydrolysates were much higher than the unhydrolyzed flaxseed protein. The hydrolysis also significantly reduced the hydrodynamic diameter of the magnitude of zeta potential of the dispersions. The gelling point of the hydrolysates occurred earlier than the unhydrolyzed sample while the duration of hydrolysis (30–120 min) did not affect gelling point of the hydrolysates. Considerable decrease in the gel strength and the frequency dependence of gel strength were observed in gels produced using hydrolyzed flaxseed protein. The above findings indicate that hydrolysates possessing high degree of antioxidative properties. The gels produces from these hydrolysates will have fast gelling property and will produce gels with reasonable strength. Thus, flaxseed protein hydrolysates obtained from trypsin hydrolysis can be used in applications that require proteins with higher antioxidative properties but softer texture.

This study investigated the heat transfer mechanism and preservation quality of axisymmetric vegetables during cold shock treatment (CST). A simulation model of heat transfer was developed based on geometrical and biological characteristics of the vegetables by finite element difference method. CST for cucumbers and carrots with cold water at 0°C (40 min), 2°C (20, 40 and 60 min) and 4°C (40 min) was conducted to evaluate the relationships between heat transfer characteristics and preservation quality. The comparative analysis shown that the simulated results agreed well with measured results. Meanwhile, in terms of weight loss, firmness and POD activity, CST with cold water at 2°C for 40 min could achieve the most positive effect on preserving cucumbers. The cucumber during treatment experienced whole variable temperature stage and appropriate constant temperature stage so as to reach optimal preservation quality.

This manuscript describes the analysis of temperature and the distribution of natural convection flow of three different cookware materials composed of stainless steel, aluminum and enameled iron, when heating olive oil. A Computational Fluid Dynamic (CFD) software, called COMSOL Multiphysics©, has been used to analyze the heat transfer process for this study. In addition, a thermographic camera and a particle tracer were employed to compare the measurements of temperature, heat transfer and flow velocity, obtained from the CFD analysis. The results demonstrated that the enameled iron was the best choice of cookware material for induction stoves, as with the increment of oil temperature, this material had the biggest contrails and oil velocity convection flow in the center of the cookware.

Squid ink tyrosinase (SIT) at levels of 300 and 500 KU kg −1 protein in combination with ethanolic extract of coconut husk (EEC) at concentrations of 1 and 1.25 g kg −1 protein was added into sardine surimi and the resulting gels were examined. The use of SIT (500 KU kg −1 protein) and EEC (1.25 g kg −1 protein) yielded the gel with the highest breaking force and deformation ( p < 0.05). Nevertheless, the expressible moisture content and whiteness scores were markedly decreased. Protein cross-linking of surimi gels increased as evidenced by the decreased band intensity of myosin heavy chain (MHC). This coincided with the increased storage modulus (G'). Based on microstructure study, finer and more compact structure of surimi gels added with both SIT and EEC were obtained, compared to the control. Thus, SIT in conjunction with EEC could be used as the novel surimi gel strengthener.

In this study, new smoothies were formulated based on low fat milk and barberry concentrate, and their physicochemical and bioactive properties were investigated. Physicochemical parameters of functional smoothie powders were obtained by applying low and high temperature drying methods, and by a combination of procedures programmed to process smoothie powders. The effect of spray drying (SP), refractance window (RW), foam mat drying (FM), spouted bed drying (SB) and a combination of spouted bed drying were studied herein, while the infrared lamp system (SBIR) shows how these methods affect the smoothie’s physical properties (such as bulk density, porosity, color) and its chemical properties (such as total anthocyanin content and antioxidant capacity measured by the DPPH method). The study also proved that an increase in the speed of rotation from 10 rpm to 100 rpm would lead to a diminished apparent viscosity from 642.39 mPas to 381.98 mPas regarding all reconstituted dried powders, which thus verifies their shear thinning behavior. The work highlighted that this new approach to combining the drying methods for the production of functional smoothie powders at an inlet temperature of 80 °C can result in the best maintenance of antioxidant activity (11.67 %) with the least moisture content (3.19 %).

The purpose of the study was to evaluate the relationship between antioxidant activity improvement and structure changes of peptide (Ser-His-Glu-Cys-Asn (SHECN) isolated from soybean treated by pulsed electric field (PEF). The two-factor-at-a–time (TFAT) was performed to investigate interaction of electric field intensity (5, 10, 15 and 20 kV/cm) and pulse frequency (1,800 and 2,400 Hz) on antioxidant activity improvement and structure changes. Compared with untreated peptide, DPPH radical inhibition of SHECN was significantly increased to 95.54 ± 0.16 % at optimal conditions (electric field intensity 15 kV/cm, pulse frequency 1,800 Hz and a retention time of 2 h). Results showed that the primary structure of SHECN had not been changed based on the nuclear magnetic resonance analysis. However, the secondary structure of peptide, especially α-helix can be changed. These results suggested that mechanism of antioxidant activity improvement is related to secondary structure changes.

Abstract: The aim of this study was to investigate the influence of solvent type, ultrasonic frequency, extraction time and temperature on the total phenolic content (TPC) and total monomeric anthocyanin (TMA) extraction from red cabbage ( Brassica oleracea var. capitata f. rubra ) using the response surface methodology (RSM) and artificial neural network. The red cabbage has been used as TPC and TMA sources due to its low cost and highly availability during all the year. The experimental data for the extraction of TPC and TMA were fitted to second-order polynomial models with higher regression coefficients than 0.902. The optimal conditions (in dry matter) for highest TPC extraction (7,049.5 mg gallic acid equivalent/kg) are: methanol as solvent, 3.60 kHz ultrasonic frequency at 67.6 °C for 59.6 min, while for TMA optimal extraction (0.3 mg/g) 2-propanol was used as solvent, 45 kHz ultrasonic frequency at 69.2 °C for 20.80 min. The artificial neural network (ANN) is better than RSM to predict the TPC and TMA extraction from red cabbage.

The content of histamine in canned fish increases during storage, because the activity of enzymes involved the enzymatic decarboxylation of free histidine is restored with time after their thermal denaturation. In order to reduce the activity of decarboxylases and the rate of histamine formation in canned fish, we propose to use cinnamon oil extract, which contains a set of fat-soluble substances with a distinct antimicrobial and enzymatic inhibition activity. Cinnamon oil extract was obtained by extraction of powdered cinnamon bark with soybean oil for 48 h followed by separation of liquid part and dense precipitate. Cinnamon oil extract was added to the canned fish instead of vegetable oil in amount of 15 % of the net weight. The histamine was determined in the canned fish immediately after canning and repeatedly storage. The analysis showed that the histamine content in the fish canned with cinnamon oil extract did not exceed 35 mg/kg after two years of storage. The control samples of the fish canned with soybean oil were characterized by accumulation of histamine up to 50 mg/kg and above. Cinnamon oil extract is recommended for use in the process of fish canning to reduce the intensity of histamine formation and to ensure safety of the product during storage.