Extraction of oil and separation/concentration of proteins using aqueous, enzymatic and membrane separation processes have been described in this article. Aqueous extraction of oilseeds has significance because of its energy efficiency and the environmental safety of the process. Also, it has been observed that the various unit operations involved in this process like grinding, solid-liquid separation, centrifugation, and drying played a vital role in the efficiency of the oil yield. It has further been demonstrated that the low yield of oil in this aqueous extraction can be enhanced by using enzymes and, in general, the enzyme mixture in combination gives better results than a single enzyme. The soluble proteins from the aqueous phase were separated using ultrafiltration membranes, thereby avoiding the generation of whey formation which otherwise is a matter of environmental concern. Even reverse osmosis membranes can be employed to process the ultrafiltered permeate to recover the secondary products and render effluent water suitable for reuse. These considerations suggest that by using these processing techniques good quality oil and protein products with better yield can be obtained from the oilseeds along with a solution addressing the associated environmental problems.
An extracellular endoinulinase P-III from Aspergillus niger 12 has been immobilized covalently onto bromoacetyl-cellulose (BAC), cellulose-carbonate (CC) and CNBr-activated Sepharose 4B (CAS) with the activity yields of 11.9, 24.1 and 19.3%, respectively, under optimal reaction conditions for the immobilization. All three immobilized enzymes increased the resistance to inactivation by p-chloromercuribenzoate or Fe3+. Mn2+ stimulated the activities of the immobilized endoinulinases onto CC (160%) and CAS (168%) more remarkably than those of free and BAC-immobilized enzymes (124%). The marked rise from 45 to 60°C in the optimal temperature for inulin hydrolysis was observed in the CAS-immobilized enzyme. The pH stability decreased on the acidic side and increased slightly on the alkaline side in the BAC-immobilized enzyme, and shifted to the acidic side in the CC-immobilized enzyme. The Km value decreased in the BAC-immobilized enzyme and increased in the CAS-immobilized enzyme.
Proximate composition, mineral content, soaking and cooking characteristics of five popular Kenyan bean cultivars were investigated. Significant differences (α=0.05) were obtained in moisture, crude fiber and crude ash contents among the bean cultivars, but not in crude protein, crude fat or carbohydrates. A three-parameter logistic model was found to reasonably describe the soaking process and afforded estimation of equilibrium moisture content value and the time necessary to attain this value. The predicted equilibrium moisture value was dependent on crude fiber content. The time required to attain equilibrium moisture was cultivar-dependent and inversely related to the logistic rate constant. The higher the ratio of divalent to monovalent cations, the higher was the mean peak compressive force of some (but not all) cooked bean samples. However, no clear relationship could be discerned between soaking rate and bean cookability.
Ttypsin and α-amylase were immobilized on glycosylated egg white-beads by simple incubation of the beads in a solution of an enzyme for 24 h at 30°C. This process included no artificial chemical modification. The obtained immobilized enzymes had a longer lifetime in continuous operation than those of the enzyme immobilized on cation exchanger or chitosan beads. The stability of the immobilized amylase was comparable with that of the enzyme immobilized on cyanogen bromide activated agarose-beads for which inactivation was not observed. The causes of the inactivation of these various types of immobilized enzymes were examined by enzyme leakage analysis from a chamber packed with the immobilized enzymes and by enzyme activity analysis by a pH-stat method. Enzyme leakage from the immobilized trypsin caused inactivation of the egg white beads and the cation exchanger, while coverage of the bead surface with substrate was the reason for inactivation of the chitosan beads. Almost no inactivation was observed for immobilized amylase.
The near-infrared (NIR) spectrum of fish meal was determined on a scanning spectrophotometer. The multiple linear regression (MLR) and partial least squares (PLS) regression were used for the calibration of moisture, protein and fat contents in fish meal. Both the MLR and PLS gave high correlation coefficient and low standard error of calibration. Correlation coefficients of calibration were more than 0.90 for each component. The prediction results also show high correlation coefficients (more than 0.90). The relative errors for prediction of each component were less than 9%, and for most samples were less than 6%. Therefore, NIR spectroscopy could be a useful technique for simultaneously determining moisture, protein and fat contents in fish meal. The time required for analysis of one sample is less than 3 min. It is a rapid and nondestructive method without environmental pollution. Thus, it will result in considerable time-saving, and it can be applied to on-line analysis at fish meal processing sites.
Phospholipase D (PLD) was purified from cabbage leaves. The molecular weight of purified PLD was estimated as approximately 73 and 87 kDa by gel filtration using Superdex 200 HR column and, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), respectively. The transphosphatidylation capacity for phosphatidylcholine of this enzyme reached over 90% , and the enzyme's hydrolysis efficiency for phosphatidylcholine was five-fold higher than that for phosphatidylglycerol. These findings indicated that the cabbage PLD efficiently transferred phosphatidylcholine to phosphatidylglycerol. On N-terminal amino acid sequence analysis of the band separated by SDSPAGE, two sequences with differing N-terminus were detected. This N-terminal difference may have been generated by processing during maturation of PLD.
The effects of polyphenol oxidase (PPO) activity in wheat flour on the formation of protein-bound 5-S-cysteinyl-3, 4-di-hydroxyphenylalanine (5-S-cysteinyldopa) in gluten have been studied. The wheat was milled on a test mill. PPO activity of fractionated flour was determined by measuring the O2 consumption of aqueous suspension after addition of catechol, dopa or tyrosine as substrate. PPO activity of whole wheat toward tyrosine was lower than that toward catechol or dopa. Glutens prepared with whole wheat or short bran contain higher levels of protein-bound 5-S-cysteinyldopa than those prepared with white flour. PPO activity in wheat flour was related with formation amounts of protein-bound 5-S-cysteinyldopa in gluten. Heat treatment of whole wheat flour inhibited the formation of protein-bound 5-S-cysteinyldopa in gluten. When crude enzyme extracts prepared from wheat bran were added to dough, formation amounts of protein-bound 5-S-cysteinyldopa markedly increased. By the addition of enzyme-inhibitor, formation of protein-bound 5-S-cysteinyldopa in gluten was markedly decreased. It is believed that dough prepared with flour containing a high level of PPO activity has a network of protein-bound 5-S-cysteinyldopa formed from tyrosine and cysteinyl residue of protein.
Two filamentous fungi isolated from contaminated samples which were thought to have occurred stochastically in the medium fill test in the aseptic filling production line for tea beverage were identified and studied their microbiological characteristics. The test strains were identified as Arthrinium sacchari (Speg.) Ellis and Chaetomium funicola Cooke. The optimum growth temperature was 20-25°C for A. sacchari M001 and 25°C for C. funicola M002. A. sacchari was able to grow at 5°C. The optimum growth pH was 4.0-8.0 for A. sacchari M001 and 5.0-8.0 for C. funicola M002. Because both strains had low heat resistance, it was suggested that the contamination had occurred after the UHT sterilization process in the medium fill test. When growth behavior was examined in green tea, oolong tea, barley tea and blended tea, both strains showed a delayed or inhibited growth in the catechin-containing green and oolong teas. It was suggested that tea catechin in the beverages could inhibit growth of filamentous fungi for a certain period of time. On the other hand, both strains grew rapidly in barley tea and blended tea that were low in tea catechin content.
A pectinesterase (E.C. 220.127.116.11, pectin pectylhydrolase) from the ripening stage of fruits of a miniature-fruited red type tomato (Mini-tomato) was purified 247 fold with yield of 26% by ammonium sulfate fractionation, affinity chromatography, and gel filtration. The molecular weight of the enzyme was found to be 15,000 by gel filtration and SDSPAGE. The optimum activity was at pH 7.0 and at 50°C. The enzyme was stable between pH 6 and 7 and at temperatures below 50°C. The Km value was estimated to be 0.48% for citrus pectin as the substrate. Chelating reagents were the effective inhibitors of the enzyme.
Zein was treated by thermolysin and Proleather, the latter a mixture of proteinases from Bacillus sp. The corresponding products were called SD-ZT and DA-Pro, respectively, The hydrolysates resulting from 2 h-hydrolysis by thermolysin and Proleather showed the strongest ACE inhibitory activity, and the IC50 values were 6.5 and 7.5 μg/μl, respectively. Effects of the administration of zein hydrolysates from thermolysin and Proleather on the systolic blood pressures (SBPs) were studied in SHRSP. Intragastric administration of SD-ZT and DA-Pro showed a significant decrease in the SBP at 6 and 24 h. Experimental diets were prepared by mixing 5% (w/w) of SD-ZT or DA-Pro with the control diet and were fed ad libitum to SHRSP for 5 weeks. In comparison with the control group, the elevation of blood pressure of SHRSP fed the SD-ZT diet or DA-Pro diet was suppressed from the 9th day after administration. The serum ACE activities in the DA-Pro group were lower than those in the SD-ZT group and the control group.
The composition of essential oil from yellow Thai mangoes, Keaw cultivars and other yellow Thai mango cultivars (Ok-rong, Nam Dorkmai and Choak Anand) was analyzed by GC and GC-MS. Yellow Keaw mangoes contained terpinolene as the main volatile, and (Z)-3-hexen-1-ol, 2,5-dimethyl-4-methoxy-3-(2H)-furanone and (E)-2-hexenal as the major oxygenated compounds. Ok-rong and Choak Anand mangoes possessed a similar compositional pattern of volatile components to that of the yellow Keaw cultivar. The volatile composition of those mangoes showed a similar pattern to those of other cultivars such as Sri Lanka mangoes and Philippine mango but far from Indian mangoes. Nam Dorkmai cultivar having β-caryophyllene as the main volatile showed a unique compositional pattern of volatiles.
Three peptides which inhibit angiotensin I-converting enzyme were isolated from maitake (Grifola frondosa) water extract digested by pepsin. Among them, Lys-Tyr-Thr-Phe-Ala-Val-Thr-Thr-Val-Lys-Thr-Trp-Val had the strongest angiotensin I-converting enzyme inhibitory activity with an IC50 value of 2.6 μM, and the others Gly-Pro-Ser-Gly-Pro-Ser-Gly, and Tyr-Pro-Ser also showed inhibitory activity with IC50 values of 2160 and 570 μM, respectively.
Promoter activity of the genes encoding Taka-amylase A and phosphoglycerate kinase of Aspergillus oryzae was analyzed using Escherichia coli β-glucuronidase as a reporter in a shoyu-koji mold A. oryzae KBN616. Assay of the β-glucuronidase extracted from the mycelia of the transformants grown in the media containing different carbon sources suggests that expression of the Taka-amylase A gene was not induced by starch in A. oryzae KBN616. Analysis of proteins in the culture supernatant of A. oryzae KBN616 after cultivation in starch medium supports this result. The phosphoglycerate kinase gene of A. oryzae KBN616 was shown to be expressed constitutively in the medium containing glucose and starch.
Variation of total polyphenol (TPP) and polyphenol oxidase activity (PPO) was investigated in ‘Irwin’ mango fruit in various color stages of development: green, purple, purplish red and red. Fruits used in this experiment were cultured in a plastic house. From each sample, six compounds in the skin and four compounds in the flesh were detected as polyphenol by thin-layer chromatography. The TPP content in the skin was 11-29 times higher than that in the flesh at various maturity stages varying during maturation. For PPO activity, much higher levels were detected in the skin and increased during maturation. The activity in the skin was 4-12 times higher than that in the flesh at various stages.
The inhibitory effects of 46 vegetable and herb extracts on hyaluronidase (EC 18.104.22.168), which is known to be related to inflammation and involved in migration of tumor cells, were examined. Twenty-two extracts showed inhibitory activity, and the extracts of 8 Labiatae plants and borage demonstrated potent inhibition of hyaluronidase. The hyaluronidase-inhibitory compound was isolated from the MeOH extract of leaves of lemon balm, which showed the strongest inhibition among them, by a combination of partition between solvents, Amberlite XAD-7 column chromatography and ODS-HPLC. Mostly on the basis of spectrometric techniques, the hyaluronidase inhibitor in lemon balm was identified with rosmarinic acid.