Advanced Materials Research Vols. 781-784

Abstract: Aroma compounds from the Maillard reaction of the l-ascorbic acid and l-methionine system were investigated. The mixture was heated while stirring at 142±2°C for 2 h in an oil bath at five different pH values (5, 6, 7, 8, or 9). Analysis of the reaction mixture was performed by headspace-SPME–GC–MS technique, and further use of LRI. 27 Components, comprising 11 pyrazines, 5 thiophenes, 6 aliphatic S compounds, 4 furans (non-S-containing) and 1 phenol, were identified. The studies showed that furans (non-S-containing), 4-hydroxybenzo[b]thiophene and 2,3,5-trithiahexane were formed mainly at acidic pH. In contrast, higher pH values could promote the production of pyrazines, acylthiophenes, 2-(isopropylthio)thiophene, methyl butanedithioate and 2,4-di-tert-butylphenol. The effect of pH on the formation of other compounds did not follow a consistent pattern.

Abstract: Ultrasonic-freeze-thaw-cycle assisted extraction was used to synchronously extract polysaccharide and phycobiliprotein from Gracilaria lemaneiformis. Firstly, different solvents (deionized water, sodium hydroxide, phosphate buffer solution (PBS) and calcium chloride solution) were screened, and PBS (1 mM, pH 6.8) was considered as the best solvent for its OD₅₆₅ value (0.086±0.0003) and OD₅₉₅ value (0.471±0.002), which was significantly higher than any other solvents (p<0.05). Moreover, an L₉ (3)⁴ orthogonal test was carried out to optimize extraction conditions, based on the single-factor test. The results indicated that the optimized conditions were fixed as follows: the ratio of solid to liquid 1:25 (w/v), 2 times of freeze-thaw cycles, ultrasound power 320 W and ultrasound time 10 min, which obtained the optimum yield and purity of polysaccharide and phycobiliprotein, 30.54%, 1.36% and 0.296, respectively. As a result, ultrasonic-freeze-thaw-cycle assisted extraction is considered to be an effective, economic and eco-environmental method to extract polysaccharide and phycobiliprotein.

Abstract: Six moulds were isolated from Luzhou-flavor Daqu through traditional microorganism isolation method. Among them, two strains njsys-3 and njsys-6 have shown higher glucoamylase activity, their enzyme activity were 1842 U/g and 2349U/g separately. Molecular biological identification results shown that strain njsys-3 was Aspergillus clavatus and strain njsys-6 was Aspergillus niger. Daqu-making test showed that once the inoculating amount of seeding broth of njsys-3 attached to 6 ‰, the glucoamylase activity of Daqu can increase 26.9%; when the inoculating amount of seeding broth of njsys-6 attached to 6 ‰, the activity of glucoamylase of Daqu can increase 34.1% and the fragrance of Daqu can increase.

Abstract: This article focused on the study of frozen storage temperatures effect on protein of crisp grass carp, and then induced changes of texture of crisp grass carp muscle. During frozen storage, lower temperature, better texture of crisp grass carp muscle. The little changes of texture characteristics of crisp grass carp were related to lower changes of drip loss, cooking loss, protein solubility and thermal stability. The results indicated that lower temperature of frozen storage was beneficial to maintain the mastication of crisp grass carp.

Abstract: Rbcl gene of 13 Lilium species were amplified, sequenced and analyzed. By comparing the rbcL sequences with 32 other species retrieved from GenBank, the sequence divergences and the phyletic evolution were analyzed and the phylogenetic tree was constructed. All rbcL sequences across 45 species are 732 bp with an average GC content of 45.1%. Potentially parsimony informative characters (PIC) are 39. From the phylogenetic tree, it can be found that it consists of three branches which are Liliaceae Lilium (I), other Liliaceae genus (II), Trilliaceae and Palmae (III).3D model was structured by homology comparative SWISS-Model online and showed with RasTop sofeware.The evolutionary analyses from the site-specific model, the 142nd and 225th codon sites are found to be under positive selection in rbcL gene.

Abstract: A simple and reliable method of high-performance liquid chromatography with pre-column derivatization was developed to evaluate the quality of Oriental Latrine Fly Larvina through establishing chromatographic fingerprint. The separation was performed on a welch Ultimate XB-C8 column with a liner gradient elution of acetonitrile and acetate buffer. The developed method was validated by precision, stability and recovery. This study indicated that the chromatographic fingerprint analysis can be readily utilized as a quality control method for oriental latrine fly larvina.

Abstract: The effects of plastic film variety (including OPP, CPP, PP₆, PP₁₂, PO, HDPE and LDPE) on the changing of O₂ and CO₂ content were investigated during the preservation storage of kyoho grape with modified atmosphere package (MAP). The gas composition was mainly affected by grape respiration rate and the permeability of packaging film. The results showed that OPP, CPP, and PP₁₂ could be better for maintaining the desired atmosphere composition of O₂, CO₂ and N₂ on grape preservation. OPP, CPP, and PP₁₂ contributed greatly to restrain grape respiration rate and extend the shelf life of grape and would be more suitable for grape preservation as modified atmosphere package.

Abstract: In this paper, the dorsal meat of grass carp was used as research object. The volatile compounds of grass carp were extracted and concentrated by headspace solid phase micro-extraction (HS-SPME). Then the volatiles were identified by gas chromatography-mass spectrometry (GC-MS). The results showed that SPME-GC-MS was effective to analysis of the volatiles in grass carp meat. According to GC-MS, 42 volatile compounds were detected in dorsal meat of grass carp. The volatile components are mostly carbonyl compounds and alcohols, and the relative contents are 95.74%. The method of odor activity value was applied to determine predominant volatile components of grass carp. There are 12 predominant components were determined in dorsal meat of grass carp, including: 1-Octen-3-ol, 2,6-Nonadienal, Nonanal, (E,E)-2,4-Decadienal, (E,Z)-2,4-Decadienal, Hexanal, 2-Nonenal, Octanal, 2-Decenal, Heptanal, Heptanol and 2-Octenal etc. The study will enrich the theoretical knowledge of flavor chemistry .

Abstract: To optimum the chelation technology of whey protein hydrolysate with calcium, the response surface method was used to investigate optimized technological conditions. The result showed that the optimum process parameters for the whey protein hydrolysate-calcium chelation were whey protein peptide and CaCl₂ ratio of 24 : 1 (w/w), whey protein hydrolysate concentration 3.5 %, pH 7.5, reaction time 20 min, reaction temperature 30 °C. Finally, the optimum level was established and whey protein hydrolysate-calcium chelate was obtained, which can provide basic theories for the following function and activity evaluation of this potential calcium supplement.

Abstract: Aiming at the problem that higher alcohols has too high level in mulberry wine, the factors which have impact on the production of higher alcohols during alcoholic fermentation in mulberry wine was studied, including pH, fermentation temperature, inoculation, SO₂, the amount of nitrogen. The results showed that: higher alcohols formation was significantly reduced when increase inoculation or lower the pH and fermentation temperature. Added nitrogen lead to the increasing formation of higher alcohols. With the increased levels of SO₂, higher alcohols formation increased in a certain range. The higher alcohols formation was inhibited when the SO₂ content up to 200.00mg/L.