Advanced Materials Research Vols. 881-883

Abstract: Poly-ε-lysine (ε-PL) is a natural biologicalagent, it is water soluble, biodegradable, and non-toxic, so it can be used as food preservatives. Through sensory evaluation, pH, total volatile basic nitrogen (TVB-N), total bacteria count (TBC) and K-values analyses, the effect of poly-ε-lysine (ε-PL) on tilapia fillets stored at 4°C was investigated. The results showed that each indicator correlated well with the storage time, and ε-PL could extend the shelf-life of tilapia fillets under refrigerated condition for at least4 days in comparison with the control group. Comparison tests indicated that 0.6% solution of ε-PL has better preservation effect than 0.2% and 0.4% ε-PL solutions.

Abstract: The objective of this study was to examine the effect of different levels of catfish bone paste to flour on the physicochemical, textural and crumb structure properties of steamed bread. Six different levels (0, 1, 3, 5, 7,10 %) of catfish bone paste to flour were used in the formulation of the steamed bread. The results showed that the weight loss and TTA of steamed bread decreased with an increase in the levels of the catfish bone paste. On the other hand, the pH increased with an increase in the levels of the catfish bone paste. The specific volume, hardness, chewiness and gas cell structure in the crumb of steamed bread with catfish bone paste at 5% supplementation level were better. Thus, a value of 5% catfish bone paste was considered a better level for incorporation into the steamed bread.

Abstract: The continuous flow chemical analyzer was applied for the determination of the content of total acid, reducing sugars and free amino acids of Luzhou-flavor Daqu in the whole making process including fermentation and storage period. The result showed that the total acid, reducing sugars and free amino acids had a dramatic change in the period of Daqu fermentation and had a higher level with a small fluctuation in the prophase of Daqu storage. In the late phase of Daqu storage, the total acid and reducing sugars decreased considerably and tend to be stable finally, while the free amino acid was still maintained at a high level. The total acid and reducing sugar had a significant positive correlation (the correlation coefficient of total acid and reducing sugar content was 0.946,P<0.01), and both of them had no correlation with the content of free amino acid.

Abstract: The functional properties of protein isolate and major protein fractions prepared from Changbai Mountain pine nuts were investigated. Albumin, globulin, glutelin, and protein isolates were obtained after the Osborne method and alkaline dissolution and acid precipitation, and protein contents of the fractions are 48.02%, 81.93%, 83.02%, and 89.69%, respectively. For the sulfhydryl contents, albumin is the highest, and glutelin is the lowest. In a disulphide bond, the protein isolate content is the highest with a value of 28.74 μmol/g, and the glutelin content is the lowest with the value of 13.46 μmol/g. For the four kinds of proteins, the essential amino acids in percentage of total amino acids are 31.13%, 34.22%, 30.30%, and 34.54%, respectively. The pH dependent protein solubility profile reveals that the minimum solubility is at pH 5.0, which corresponds to the isoelectric point. Protein isolate has the minimum water absorption capacity with a value of 0.59 ml/g. On the other hand, albumin has the minimum oil absorption capacity with a value of 2.11 ml/g. The emulsifying activity and stability and the foaming activity and stability increased with increasing concentration of four kinds of proteins. SDS-PAGE results showed that these four kinds of proteins have different molecules.

Abstract: In the present study, the crude polysaccharides were extracted from the microalgae Gracilaria lemaneiformis with ultrasonic-assisted extraction method and purified by DEAE-52 cellulose chromatography and Sephadex G-100 size-exclusion chromatography in that order. Two main fractions, GPC-1and GPC-2, were obtained through the extraction and purification steps. Then partial characterizations, such as chemical composition, ultraviolet (UV) spectrum and infrared (IR) spectrum of the two fractions were analyzed in this study. The results indicated that the total sugar contents of GPC-1and GPC-2 were 89.32% and 88.79%, and the protein contents of these two fractions were only 0.35% and 0.76%, compared with that of crude polysaccharides of 75.49% and 1.92%, respectively. Moreover, both the UV spectrum and the IR spectrum demonstrated that the two fractions were typical purified polysaccharides. As a consequence, these investigated characterizations could be considered as a favorable evidence for the identification of polysaccharides from Gracilaria lemaneiformis.

Abstract: In order to fully exploit the truffle resources, this article took fresh and mature truffles as raw material, studied on extraction and detection of α-androstenol. The experiment used acetone as extracting agent and used ultrasonic wave extraction method to extract α-androstenol. Then the extracting solution was concentrated by Termovap Sample Concentrator, and was detected by GC-MS. The results showed that: using acetone as extraction agent, ultrasonic temperature at 50°C, ultrasonic frequency in 40KHZ, time for 60min, after concentrated and detected by external standard method for quantitative. The detected results showed that: in mature truffles, the content of α-androstenol was 0.0193μg/100g, the content of its isomeric compounds was 0.707μg/100g; in immature truffles, the content of α-androstenol was 0.0087μg/100g, the content of its isomeric compounds was 0.238μg/100g.

Abstract: In order to reveal the effect of packaging films on quality of fresh cut broccoli, three different properties of films were selected as materials. The effect of packaging films on headspace gas composition in the bag, respiratory rate and sensory quality of fresh cut broccolis were studied. The results showed that the samples in PE2 exhibited the best quality. The samples in PE1 had less quality than PE2. Although broccolis in PE3 had the lower O₂ concentration and highest CO₂ concentration, which retarded a great extent of respiration rate than others, but this condition induced anaerobe respiration, and then leading to the worst sensory quality.

Abstract: The main aim of the present work was to optimize mead production using Response Surface Methodology. The effects of pH (X1:4–6), diammonium phosphate concentration (X2: 90–150g/hL), and temperature(X3: 24–32°C) on mead quality, concerning the final ethanol, was studied. The results showed that regression equation fit well with experimental data and the optimum extraction conditions determined in order to maximize the combined responses were pH value of 6.5, diammonium phosphate concentration of 150g/hL, temperature of 28°C. The mead produced under these conditions had the following characteristics: ethanol concentration of 9.3% and good flavor.

Abstract: The high concentration of sodium pyroglutamate could reduce the yielding amount of monosodium glutamate in the last monosodium glutamate mother liquor. In this study, on the basis of the single factor experiment, the optimization was explored with response surface methodology for acid hydrolysis conditions of the simulated last monosodium glutamate mother liquor. It is indicated that treatment time (X₁) was the most significant factor to affect the removal efficiency of pyroglutamic acid, followed by treatment temperature (X₂) and concentration of acid (X₃). The regression model for the acid hydrolysis was significant (p<0.0001). The influence of the interaction between X₁ and X₃ was very significant on removal efficiency of pyroglutamic acid. Meanwhile, the optimized conditions obtained were: 2.67h of treatment time, 34.53% of concentration of acid and 109.7°C of treatment temperature. Under these conditions, the maximum removal efficiency of pyroglutamic acid was up to 95.32%, which was close to the predicted value of 95.94%.

Abstract: In this manuscript, flavor compounds development of Cheddar Cheese with addition of soybean pectin gel was investigated during ripening. A rapid and simple Solid-Phase Microextraction (SPME) procedure was used for identifying and classifying the volatile compounds. The result showed that addition of soybean pectin gel to cheese had similar flavor profiles with full-fat cheeses. Higher levels of acid volatile compounds and aldehydes were obtained in comparison with experimental cheese. Results simultaneously indicated that experimental cheeses contained high concentrations of volatile amine as soybean pectin gel promoting the volatile substances.