超临界水氧化法处理丙烯腈剧毒废水的实验研究

丙烯腈生产过程中排放的废水为高浓度剧毒有机废水,采用焚烧等方法处理均不能满足环保要求.使用2.0 L的超临界水氧化反应器对该废水进行处理实验研究.实验结果表明,当反应温度为650℃,压力为28 MPa,氧气过量为理论量的200%,反应时间为180 s时,COD最高去除率可达到99.998%.笔者考察了反应温度、压力、时间、氧气浓度以及催化剂等对COD去除率的影响.处理后出水水质中的COD、氢氰酸、色度、pH等指标均达到国家规定的《污水综合排放标准》.     

Effects of Solvent, Temperature, Time, Solvent-to-Sample Ratio, Sample Size, and Defatting on the Extraction of Soluble Sugars in Soybean

ABSTRACT Extraction solvent, temperature, time, and solvent‐to‐sample ratio were studied to identify the optimal conditions for extracting sugars from nondefatted soybean. Water and 10%, 50%, and 80% (v/v) ethanol were used as the solvents. Extraction temperatures of 25 °C, 50 °C, and 80 °C, for 15, 30, and 60 min and solvent‐to‐sample ratios of 5:1, 10:1, and 15:1 (v/w) were combined with different solvents. The sugar composition in the soybean extracts was analyzed by high‐performance anion‐exchange chromatography with pulsed amperometric detection. The sugar appropriate to be used as the standard in the phenol‐sulfuric acid method in sugar quantification, and effects of sample size and defatting on sugar extraction were also evaluated. The optimum extraction protocol concluded from this study includes the use of water as the solvent at a solvent‐to‐sample ratio of 5:1 at 25 °C or 50 °C for 15 min. Sucrose was shown to be the best sugar as the standard to quantify the total soluble sugars in soybean. Extractions from sample size of 1 g and 0.1 g yielded similar soluble sugars. A greater amount of sugars was extracted with the defatted soybean meal than with the nondefatted sample.     

Quality attributes of vegetable soybean as a function of boiling time and condition

Vegetable soybeans are marketed fresh or frozen, either shelled or in pods. The objective of this research was to characterise the change in quality attributes of vegetable soybean with boiling time (0–20 min), and presence/absence of pods, using an electrical-resistance stove or a steam-jacketed kettle. Trypsin inhibitor activity (TIA), texture, colour, soluble sugars, nitrogen, calcium and iron content were analysed. Blanching using a steam-jacketed kettle for approximately 2 min rendered 80% inactivation of TIA, and resulted in high colour, texture and sucrose. There were no differences between blanching in pods or shelled for TIA, colour and texture; however, blanching in pods prevented losses of sucrose. Blanching did not affect iron, mono- and oligosaccharide levels, but increased nitrogen and calcium content. Additionally, we observed that all traits decreased linearly with cooking time when using an electrical-resistance stove, except for calcium and nitrogen that increased, and oligosaccharides that remained constant.     

绿叶蔬菜冻干试验研究

通过对菠菜和香葱的预处理、速冻、冻干脱水及复水性研究,确定了相应的预处理工艺、共晶点和冻干工艺。     

Relationships between protein and other chemical composition and texture of tofu made from soybeans grown in different locations

Understanding quantitative relationships between protein and other chemical components in diverse soybean genotypes (lines) grown in different locations and the firmness of tofu can provide scientific insight for selecting soybean suitable for tofu making. Locations showed significant effects on seed components, including total protein, major storage proteins, subunits and polypeptides of the major storage proteins, and calcium, but not magnesium or phytic acid. Results showed that 11S content, but not 11S/7S ratio, was only correlated with filled tofu firmness when analyzed over all locations. A strong and positive correlation between firmness and A₃ polypeptide of the 11S protein content was found for both pressed tofu (r = 0.80, p < 0.001) and filled tofu (r = 0.76, p < 0.001) over three locations (overall pooled data) and within most individual locations. The correlation of filled tofu firmness and A₃ polypeptide was significant for each of the three individual locations. However, the correlation of pressed tofu firmness and A₃ polypeptide content was significant at two of three locations. Mean calcium content was positively correlated with mean pressed and filled tofu firmness over all locations, but calcium was not correlated with pressed tofu firmness at any individual location, and only one location showed a significant correlation of calcium and filled tofu firmness. In addition, pressed tofu firmness was found to be negatively correlated with tofu yield. The findings that A₃ polypeptide's strong relationship with tofu firmness within certain locations may be used by the food industry to select proper soybean for manufacturing tofu and to facilitate tofu soybean breeding for tofu making.     

Characteristics and Functionality Enhancement by Glycosylation of Bitter Melon (Momordica charantia) Seed Protein

Seeds of ripe bitter melon (Momordica charantia) contain approximately 30% protein. However, this protein, which is less functional than soy protein, may have desirable functionalities as a food ingredient after modification. Bitter melon seed protein isolate (BMSPI) was prepared under optimal extraction conditions (defatted meal to 1.3 M NaCl was 1:10 w/v; pH 9.0) and its functional properties were investigated before and after modification by glycosylation. Glycosylation was conducted at varying relative humidities (50%/65%/80%) and temperatures (40 °C/50 °C/60 °C) using a response surface central composite design. Degree of glycosylation (DG) ranged from 39.3 to 52.5%, 61.7 to 70.9%, and 81.2 to 94.8% at 40 °C, 50 °C, and 60 °C, respectively (P values < 0.0001). Denaturation temperatures of all DGs ranged from 111.6 °C to 114.6 °C, while unmodified/native BMSPI had a value of 113.2 °C. Surface hydrophobicity decreased to approximately 60% when the DG was maximal (94.8%). Solubility decreased almost 90% when the DG was maximal in comparison to the native BMSPI (62.0%). Emulsifying activity increased from 0.35 to 0.80 when the DGs were ≥80%, while emulsion stability increased from 63 to 72 min when the DGs were greater than 70%. A similar trend was observed with foaming capacity and foaming stability of the glycosylated proteins. This glycosylated BMSPI with improved emulsifying and foaming properties could be used as an ingredient in food products where such properties are required.     

Antimicrobial Activities of Phenolic Extracts Derived from Seed Coats of Selected Soybean Varieties

Soybean hulls or seed coats consist of complex carbohydrates, proteins, lipids, and polyphenols such as anthocyanidins, proanthocyanidins, and isoflavones. The polyphenolics in the seed coats give them various colors such as black, brown, green, yellow, or even a mottled appearance. In this study, the antimicrobial effects of phenolic extracts from the seed coats of different colored soybeans (yellow, dark brown, brown, and black) were evaluated against foodborne pathogens such as Salmonella Typhimurium, Escherichia coli O157:H7, and Campylobacter jejuni in broth‐cultures as well as on chicken skin. The highest total phenolic content was observed for the phenolic extract from soybean variety (R07‐1927) with black colored seed coat (74.1 ± 2.1 mg chlorogenic acid equivalent [CAE]/g extract) and was significantly different (P <0.0001) from the extract of the conventional soybean variety (R08‐4004) with yellow colored seed coat (7.4 ± 1.2 mg CAE/g extract). The extract from black colored soybean produced reductions of 2.10 ± 0.08 to 2.20 ± 0.08‐log CFU/mL for both E. coli O157:H7 and C. jejuni after 3 d when incubated in broth‐culture having 4‐log CFU/mL of bacteria, whereas a 6 d incubation was found to reduce S. Typhimurium and E. coli O157:H7 at 2.03 ± 0.05 and 3.3 ± 0.08‐log CFU/mL, respectively. The extract also reduced S. Typhimurium and E. coli O157:H7 attached to chicken skin by 1.39 ± 0.03 and 1.24 ± 0.06‐log CFU/g, respectively, upon incubation for 6 d. Soybean seed coat extracts may have a potency as antimicrobial agents to reduce foodborne bacteria contaminating poultry products.     

Amino Acid Profiles of 44 Soybean Lines and ACE‐I Inhibitory Activities of Peptide Fractions from Selected Lines

Soybeans are cultivated in the United States chiefly for cooking oil, while the residue after oil extraction (soybean meal) is mostly used in animal feed formulations. High protein content in the defatted soybean meals led to the extraction of pure protein and its application in food products. We selected 44 soybean lines to determine their moisture and protein contents, and their amino acid composition was investigated. Soybean lines with high protein content, one high yielding (R95‐1705), and two high oleic acid (N98‐4445A, S03‐543CR), were selected for protein isolate preparation, hydrolysis using alcalase and gastro‐intestinal (GI) resistance. Furthermore, the GI resistant hydrolysates were fractionated and tested for angiotensin‐I‐converting enzyme (ACE‐I) inhibition activity. The amino acid analysis showed high methionine in the high protein and fatty acid lines (R05‐4494 and R05‐5491), and high cysteine content in one of the high oleic acid soybean line CRR05‐188 in comparison to the check lines (UA‐4805 and 5601‐T). The protein isolate with the highest purity (90–93 %) was derived from the selected lines N98‐4445A and S03‐543CR, and hydrolyzed using alcalase enzyme. The protein hydrolysates (500 µg/mL) showed inhibition of the ACE‐I by 49 %. The results from this study will promote the use of high oleic acid soybeans as a source of protein and peptides with functional activities.     

Protein extraction optimisation,characterisation, and functionalities of protein isolate from bitter melon (Momordica charantia) seed

Bitter melon seeds are a rich source of protein. Optimum conditions for protein extraction from the seeds, determined using a response surface design, were at a pH 9.0 and 1.3 M NaCl. Soy protein isolate (SPI) was included for comparison. Surface hydrophobicity of bitter melon seed protein isolate (BMSPI) (690) was significantly higher than that of SPI (399). Electrophoretograms of BMSPI showed bands at 40 and 55 kDa, and at 22, 25, and 35 kDa in non-reducing and reducing buffers, respectively. BMSPI had most of the essential amino acids and hence could be considered as a high quality protein. BMSPI had a single denaturation temperature (113.1 °C) while SPI had two denaturation temperatures (78.0 and 94.8 °C). The proteins exhibited U-shaped curves with solubilities ranging from 62.0% to 67.5% for BMSPI and 86.7% to 90.1% for SPI at pH ? 7.0. BMSPI had lower emulsifying activity (0.36 vs. 0.73), foaming capacity (39.6 vs. 61.0 ml), and foaming stability (21.5 vs. 25.5 min) than had SPI.     

Comparison of two HPLC systems and an enzymatic method for quantification of soybean sugars

Successful breeding programs need fast and reliable methods for analyzing sugar composition in new soybean (Glycine max (L.) Merrill) lines. The efficiency to quantify the major sugars, including glucose, fructose, sucrose, raffinose, and stachyose, in five soybean lines with two HPLC systems and an enzymatic procedure were compared. Soluble sugars in soybean were extracted with water at a solvent-to-sample ratio of 5:1 at 50 °C for 15 min, and analyzed by high-performance size exclusion chromatography with refractive index detection (HPSEC-RI), high-performance anion-exchange chromatography with pulsed-amperometric detection (HPAEC-PAD), and a raffinose-series oligosaccharides assay procedure. All three methods produced comparable and reproducible results. The HPAEC-PAD method was more sensitive, faster and capable of separating all five major sugars in soybean with improved peak resolution compared with the HPSEC-RI method, and is recommended for soybean breeding programs. The enzymatic procedure required no expensive instrumentation and less sample preparation, but could not quantify individual raffinose and stachyose.