Inactivation Of Trypsin Inhibitors Research Articles

Bioconversion of cyanobacteria by black soldier fly larvae (Hermetia illucens L.): Enhancement by antioxidants

Cyanobacterial blooms have been a global environmental problem for decades. Bioconversion by black soldier fly larvae (BSFL) has been widely reported to be a clean and efficient method to remove organic pollutants. In this study, BSFL bioconversion was used to treat cyanobacterial blooms. Antioxidants (a mixture of l-ascorbic acid [180 mg/kg fresh feed] and α-tocopherol [360 mg/kg fresh feed]) were added to compare bioconversion performance against a non-supplemented group. With increasing proportions of cyanobacteria (0%–25% dry mass), the bioconversion efficiency of the antioxidant group improved significantly compared to the control group, and the survival rate of larvae rose from 96.50–45.50% to 98.00–55.83% with antioxidant addition. The toxic effects of exogenous anti-nutrients could be reduced by the antioxidants through inactivation of trypsin inhibitor and enhancement of the microcystin-LR degradation rate. Overall, the BSFL bioremediation capacity was improved with addition of exogenous antioxidants, verifying both the effects and mechanism of antioxidant addition in promoting the bioconversion of cyanobacteria by BSFL and providing a basis for future application and study.

Rotating-Pulsed Fluidized Bed Drying of Okara: Evaluation of Process Kinetic and Nutritive Properties of Dried Product

Okara is a byproduct of soymilk processing and is rich in fiber and protein. It is underutilized in the food industry as an ingredient owing to its high perishability. The objective of this work was to study the drying of okara in a rotating-pulsed fluidized bed dryer to verify the effect of air temperature (50–90 °C) and frequency of disc rotation (7.5–24.5 Hz) on the inactivation of trypsin inhibitors and the retention of the total phenolic compounds and isoflavones. The drying process was effective in drying this cohesive material. The process conditions exhibited no significant effect on the activity of trypsin inhibitors and content of total isoflavones. However, the content of total phenolic compounds was affected by the air temperature, in which the higher retention occurred at 70 °C and 16 Hz. Regarding the conversion of isoflavone classes, the drying process favored the hydrolysis of malonylglycosides and β-glycosides into aglycones.

Roles of Autophagy and Pancreatic Secretory Trypsin Inhibitor in Trypsinogen Activation in Acute Pancreatitis.

The focus of the review is on roles of autophagy and pancreatic secretory trypsin inhibitor (PSTI), an endogenous trypsin inhibitor, in trypsinogen activation in acute pancreatitis. Acute pancreatitis is a disease in which tissues in and around the pancreas are autodigested by pancreatic digestive enzymes. This reaction is triggered by the intrapancreatic activation of trypsinogen. Autophagy causes trypsinogen and cathepsin B, a trypsinogen activator, to colocalize within the autolysosomes. Consequently, if the resultant trypsin activity exceeds the inhibitory activity of PSTI, the pancreatic digestive enzymes are activated, and they cause autodigestion of the acinar cells. Thus, autophagy and PSTI play important roles in the development and suppression of acute pancreatitis, respectively.

Comparison of Conventional and Microwave Treatment on Soymilk for Inactivation of Trypsin Inhibitors and In Vitro Protein Digestibility.

Soymilk is lower in calories compared to cow’s milk, since it is derived from a plant source (no cholesterol) and is an excellent source of protein. Despite the beneficial factors, soymilk is considered as one of the most controversial foods in the world. It contains serine protease inhibitors which lower its nutritional value and digestibility. Processing techniques for the elimination of trypsin inhibitors and lipoxygenase, which have shorter processing time and lower production costs are required for the large-scale manufacturing of soymilk. In this study, the suitable conditions of time and temperature are optimized during microwave processing to obtain soymilk with maximum digestibility with inactivation of trypsin inhibitors, in comparison to the conventional thermal treatment. The microwave processing conditions at a frequency of 2.45 GHz and temperatures of 70 °C, 85 °C and 100 °C for 2, 5 and 8 min were investigated and were compared to conventional thermal treatments at the same temperature for 10, 20 and 30 min. Response surface methodology is used to design and optimize the experimental conditions. Thermal processing was able to increase digestibility by 7% (microwave) and 11% (conventional) compared to control, while trypsin inhibitor activity reduced to 1% in microwave processing and 3% in conventional thermal treatment when compared to 10% in raw soybean.

Combined high hydrostatic pressure and thermal treatments fully inactivate trypsin inhibitors and lipoxygenase and improve protein solubility and physical stability of calcium-added soymilk

Abstract The objective of this work was to assess the possibility of obtaining calcium-added soymilk with acceptable characteristics regarding protein solubility and physical stability, and inactivation of trypsin inhibitors and lipoxygenase, through a combined thermal-high hydrostatic pressure treatment. A Doehlert design was applied to study the effect of combining pressure levels (500–700 MPa), initial temperatures (45–65 °C) and CaCl 2 concentrations (5–15 mmol L − 1 ). Results showed that protein solubility was a function of CaCl 2 concentration (p Industrial relevance An analysis of the effect of the combination of high hydrostatic and thermal treatments on calcium-added soymilk is introduced in the present study. Some processing conditions were found to allow the obtention of a product with improved protein solubility and physical stability, and with inactivated trypsin inhibitors and lipoxygenase enzyme. This information could be beneficial considering the reduction of process time and energetic costs, because the assayed combination of thermal and high pressure treatments takes advantage of the instantaneous compression heating. Thus, the results provided in the present work could be useful to prepare an acceptable calcium-added soymilk.

The effect of thermal treatment of whole soybean flour on the conversion of isoflavones and inactivation of trypsin inhibitors

The aim of this paper was to evaluate the effect of the thermal treatment of whole soybean flour (WSF) on the conversion of isoflavones and the inactivation of trypsin inhibitors. Soybeans were ground and whole soybean flour was obtained and subjected to heat treatment in an oven for 10, 15 and 20min at 100, 150 and 200°C according to a 32 experimental design. The response functions were taken to be the contents of different isoflavone forms and the residual activity of trypsin inhibitors. The thermal treatment in the oven altered the content and profile of the different isoflavones forms. At 200°C for 20min, there was a higher conversion of malonylglycosides to acetylglycosides, β-glycosides and aglycones and a significant reduction in the activity of trypsin inhibitors. Mathematical models were established to estimate the process parameters in obtaining the WSF with isoflavone conversions and reductions in trypsin inhibitor activity.

The Heat-Induced Protein Aggregate Correlated with Trypsin Inhibitor Inactivation in Soymilk Processing

Kunitz trypsin inhibitor (KTI) and Bowman-Birk inhibitor (BBI) have trypsin inhibitor activities (TIA), which could cause pancreatic disease if at a high level. It is not clear why some KTI and BBI lose TIA and some does not in the soymilk processing. This would be examined in this study. TIA assay showed residual TIA was decreased with elevated temperature and TIA was decreased quickly in the beginning and then slowly in boiling water bath. Interestingly, ultracentrifugation showed low residual TIA soymilk had more precipitate than high residual TIA soymilk and soymilk TIA loss had a high correlation coefficient (R(2) > 0.9) with precipitate amount. In addition, the TIAs of floating, supernatant, and precipitate obtained by ultracentrifugation were assayed and >80% residual TIA was concentrated in the supernatant. Tricine-SDS-PAGE showed KTI in supernatant was mainly a noncovalent bound form which might exist as itself and/or incorporated into a small protein aggregate, while KTI in precipitate was incorporated into a protein aggregate by disulfide and/or noncovalent bonds. Chymotrypsin inhibitor activity (CIA) assay showed about 89% of the original CIA remained after 100 °C for 15 min. Ultracentrifugation showed that >90% residual CIA was concentrated in supernatant. Tricine-SDS-PAGE showed soymilk (100 °C, 15 min) BBI mainly existed in supernatant but not in precipitate. It was considered that BBI tended to exist as itself with its natural conformation. Thus, it was suggested residual TIA was mainly from the free BBI and TIA inactivation was mainly from KTI incorporation into protein aggregate. This study is meaningful for a new strategy for low TIA soymilk manufacture based on the consideration of promoting protein aggregate formation.

Effects of processing on soybean nutrients and potential impact on consumer health: An overview

Production of soybeans and consumption of soy products is increasing worldwide mainly due to acclaimed health benefits. Processing can alter soybean sensory appeal, nutritive value and potentially affect consumer health. This review of the literature examines these issues. Despite potential changes in nutritive value during processing, soy foods processing below 100oC for short periods, may not adversely affectnutritive value. However, heat inactivation of trypsin inhibitors, denaturation of soybean globulins and haemagglutenins, increases soy protein bioavailability. Excessive heating can impair nutritive value by making lysine unavailable, as serine, cystine and cysteine are converted to a dehydroprotein intermediate that reacts with lysine to form lysinoalanine. Tryptophan and methionine are also lost duringexcessive heating. The acylation reaction catalyzed by alkali, generates lysinoalanine, an unavailable and potentially toxic compound. In rats, ingestion of lysinoalanine results in diarrhoea, pancreatic hyperplasia, and loss of hair. At levels present in foods, protein-bound lysinoalanine does not cause nephrotoxicity in humans. Heat treatments at alkaline pH result in destruction of arginine, which is converted to ornithine, urea, citrulline and ammonia, while cysteine is converted into dehydroalanine. Serine, threonine and lysine are also reduced at alkaline pH. Theseconditions may be present during alkali refining of soy oil. Carbohydrates with free reducing groups react with carbonyl groups on proteins as part of the Maillard reaction. Heat treatments at alkaline pH and above 200oC cause isomerization of amino acids, leading to formation of racemic mixtures of L and D forms. Since Disomers have reduced bioavailability and some including D-proline are reported to be toxic, racemization of an essential amino acid reduces its nutritional value. Changes in lipids include oxidation, loss of lipid-soluble vitamins and change of fatty acids from cis to trans isomers. Autoxidation of unsaturated fatty acids initiates free radicalformation leading to destruction of unsaturated fatty acids, with potential reduction of essential fatty acid content. Oxidized lipid-protein interaction products are important precursors of atherosclerotic plaques in vivo. Carotenoids are lost on bleaching, thereby reducing Vitamin A potential. Vitamin E is lost during oil refining. Roasting and toasting have no effect on soy isoflavones, but organic solvents remove them, while fermentation increases their bioavailability. Dehulling reduces total mineral content but most soy minerals follow protein or meal, while sodium and potassium are lost in wash water. To minimize adverse changes, minimal washing, fermentation, reduction of hydrogenation temperature and thermal processing below 100oC for short periods, are recommended.

Heat Inactivation of Trypsin Inhibitor in Kintoki Beans

Heat Inactivation of Trypsin Inhibitor in Kintoki Beans

Elimination of Trypsin Inhibitor Activity and Beany Flavor in Soy Milk by Consecutive Blanching and Ultrahigh-Temperature (UHT) Processing

Soy foods contain significant health-promoting components but also may contain beany flavor and trypsin inhibitor activity (TIA), which can cause pancreatic disease if present at a high level. Thermal processing can inactivate TIA and lipoxygenase. Ultrahigh-temperature (UHT) processing is relatively new for manufacturing soy milk. Simultaneous elimination of TIA and soy odor by UHT processing for enhancing soy milk quality has not been reported. The objective was to determine TIA in soy milk processed by traditional, steam injection, blanching, and UHT methods and to compare the products with commercial soy milk products. Soybean was soaked and blanched at 70-85 degrees C for 30 s-7.5 min. The blanched beans were made into base soy milk. The hexanal content of the base soy milk was determined by gas chromatography to determine the best conditions for further thermal processing by indirect and direct UHT methods at 135-150 degrees C for 10-50 s using the Microthermics processor. Soy milk was also made from soaked soybeans by traditional batch cooking and steaming methods. Eighteen commercial products were selected from the supermarket. Residual TIA in soy milk processed by the traditional and steam injection to 100 degrees C for 20 min was approximately 13%. Blanching could inactivate 25-50% of TIAs of the raw soy milk. The blanch conditions of 80 degrees C and 2 min were selected for UHT processing because these conditions produced blanched soy milk without hexanal, indicating a complete heat inactivation of lipoxygenases. The TIA decreased with increased temperature and time of UHT heating. The maximal trypsin inhibitor inactivation was achieved by UHT direct and indirect methods with residual activities of approximately 10%. Some commercial soy milk products contained high TIAs. The results are important to the food industry and consumers. Kinetic analysis showed that heat inactivation (denaturation) of TIA, under the continuous processing conditions of the Microthermics processor, followed first-order reaction kinetics, and the activation energy of the inactivation was 34 kJ/mol.

Improving Digestibility of Soy Flour by Reducing Disulfide Bonds with Thioredoxin

The Kunitz trypsin inhibitor (KTI) and the Bowman-Birk inhibitor (BBI) of trypsin and chymotrypsin contain disulfide bonds. Glycinin, the major storage protein in soybeans also contains disulfide bonds. Treatment of soy white flour with a NADP-thioredoxin system (NTS) effectively reduced disulfide bonds in soy flour and increased protein digestibility by trypsin and pancreatin as measured by the pH stat method. Treatment of soy flour with NTS increased the digestibility compared to soy white flour by 29.3 and 60.6% for trypsin and pancreatin, respectively. NTS-treated soy flour had similar digestibility by trypsin to autoclaved soy flour and casein, but digestibility by pancreatin was less than autoclaved soy flour and casein. The degree of reduction by NTS was highly correlated to the degree of hydrolysis (DH) by trypsin (R(2) = 0.93) and pancreatin (R(2) = 0.99). The DH of NTS-treated soy flour by trypsin is reflective of both inactivation of trypsin inhibitors and overall protein digestibility while pancreatin hydrolysis is reflective of only overall protein digestibility.

Enzymatic modification as a tool to improve the functional properties of heat‐processed soy flour

AbstractBACKGROUND: There are a number of antinutritional factors present in soybeans that exert a negative impact on the nutritional quality of the protein. Among those factors that are destroyed by heat treatment are protease inhibitors and lectins. Protease inhibitors show antinutritional effect and moreover the digestibility of the protein is limited by the presence of these antinutrients. The aims of the present study are (1) to study the effect of autoclaving on the trypsin inhibitor inactivation, nitrogen solubility and protein digestibility of defatted soy flour and (2) to study the effect of enzymatic modification on the functional properties of autoclaved soy flour.RESULTS: The solubility of the soy flour decreased with increase in autoclaving time. Partial hydrolysis of the autoclaved soy flour increased its acid solubility (pH 4.5) from 17% to 56% over a control value of 24% without affecting its functional properties. Inactivation of trypsin inhibitors improved the protein digestibility of soy flour from 25% to 95%. Particle size analysis of the autoclaved flour indicated the formation of soy protein aggregates, which resulted in poor solubility. The enzymatic modification of autoclaved soy flour resulted in its property as a good emulsifying agent with an emulsion capacity of 118 ± 4 mL.CONCLUSION: Enzymatic modification of the heat‐processed soy flour increased its solubility and other functional attributes. The increased acid solubility would be advantageous in the utilization of soy proteins in acidic foods. Thus the autoclaved and partially modified soy flour is a potential source for specific functional foods. Copyright © 2007 Society of Chemical Industry

The Role of Aromatic Amino Acid Oxidation, Protein Unfolding, and Aggregation in the Hypobromous Acid-Induced Inactivation of Trypsin Inhibitor and Lysozyme

Hypobromous acid (HOBr) generated by activated eosinophils has been implicated in tissue injury observed in asthma, allergic reactions, and some infections. Proteins are major targets for this oxidant, but the mechanisms by which HOBr induces loss of function are not well-established. In this study, we have examined the effect of HOBr on protein structure (as assessed by amino acid loss, side chain oxidation, fragmentation, aggregation, and unfolding) and activity of a model protease inhibitor, soybean trypsin inhibitor (STI), and the protective enzyme lysozyme. Exposure of both proteins to low oxidant concentrations (< or = 5-fold molar excess) results in loss of function. In each case, loss of activity is associated with the selective oxidation of His, Trp, and Tyr residues, which results in protein unfolding (with lysozyme) and protein aggregation (with STI). Reaction with these residues accounts for 25 and 50% of the HOBr with STI (25-fold excess) and lysozyme (4-fold excess), respectively. These processes are believed to lead to changes in the structure of the proteins, which disrupts substrate binding. With both proteins, the oxidation of other residues, including Met, does not appear to play a major role. Bromamines, formed by reaction with amine groups, are major products, which account for 45 and 35% of the HOBr with STI (25-fold excess) and lysozyme (4-fold excess), respectively. Decomposition of these species correlates with secondary oxidation reactions, and with lysozyme, a time-dependent loss in activity. Overall, 70% of the HOBr can be accounted for with STI and 95% with lysozyme.

Cinética de inativação de inibidores de tripsina e de insolubilização de proteínas de diferentes cultivares de soja

A soja (Glycine max (L.) Merrill) é uma das leguminosas mais estudadas, em virtude de sua intensa utilização como fonte de óleo comestível e proteína para alimentação humana e animal. A presença de inibidores de tripsina na soja limita sua utilização, tornando necessário o processamento térmico para melhorar sua qualidade nutricional. Entretanto, o processamento térmico excessivo ou inadequado pode reduzir a qualidade da proteína. Neste trabalho, foram utilizados cultivares de soja BR-36, com atividade normal de inibidores de tripsina, e cultivares BRM 95-5297 e BRM 95-5262, com baixas atividades de inibidores de tripsina. As farinhas com 10 e 16% de umidade foram aquecidas em banho a 95°C, com cinco intervalos (15, 25, 50, 75 e 100 minutos) de retenção; em seguida, foram determinados os respectivos parâmetros cinéticos de inativação de inibidores de tripsina e de insolubilização de proteínas. A partir da cinética de primeira ordem para inativação de IT e insolubilização de proteínas, observou-se que as constantes de velocidade de reação de inibidores de tripsina aumentaram, com conseqüente redução no tempo de processamento térmico dos cultivares de soja BRM 95-5297 e BRM 95-5262 quando comparados ao cultivar BR-36. O acréscimo de 6% de umidade nas farinhas também aumentou as constantes de velocidade de inativação de inibidores de tripsina e de insolubilização de proteínas.

Inactivation of trypsin inhibitors in sweet potato and taro tubers during processing.

In order to understand the extent of elimination of trypsin inhibitors during processing of sweet potato (Ipomoea batatas) and taro (Colocasia esculenta) tubers, a detailed study was conducted using tubers processed by oven drying, cooking, and microwave baking. Between 80 and 90% trypsin inhibitor (TI) activity was retained in sweet potato chips up to 2h at 70 degrees C. Among the four cultivars of sweet potatoes, RS-III-2 trypsin inhibitors were more heat labile. Heating at 100 degrees C led to rapid inactivation of TI of sweet potatoes. Varietal differences in thermal stability were more pronounced for the trypsin inhibitors of taro than sweet potatoes. Taro inhibitors were also more rapidly inactivated than sweet potato TI. Between 17 and 31% TI activity was retained in cooked tuber pieces of sweet potatoes, while only 3-10% were retained in taro cultivars. Very effective inactivation of trypsin inhibitors of sweet potatoes and taro could be obtained through microwave baking. Flour prepared from taro was devoid of TI activity, while 5-12% TI activity was retained in the flour prepared from sweet potatoes. The study clearly established that among the four techniques used, microwave baking and flour preparation were the best methods to eliminate TI from sweet potatoes and taro.

Mathematical modelling of the heat inactivation of trypsin inhibitors in soymilk at 121–154 °C

AbstractResponse surface methodology (RSM) was used to investigate the effects of processing temperature and time on the inactivation of trypsin inhibitors (TI) in soymilk. The factorial experimental design consisted of four levels of temperature and six levels of time in a temperature range of 121–154 °C and a time interval of 10–90 s. A quadratic polynomial equation, relating log(% TI retained) as a function of heating time and temperature, was satisfactorily fitted to the experimental data by least squares regression with r2 (correlationcoefficient) = 0.959. Within the range of heating times investigated, TI in soymilk was satisfactorily destroyed to 10% retained at 143 and 154 °C with 62 and 29 s heating time respectively.© 2002 Society of Chemical Industry

ばい煎大豆中トリプシンインヒビターの熱失活に及ぼす微量水分の影響

水分含量の異なる丸大豆,大豆粉およびガラス管封入大豆粉を加熱した後,残存水分量と残存TI活性を測定して次の結果を得た.(1) 大豆粉は焙煎法でTIを熱失活させるのは非常に困難であるのに対して,ガラス管に封入した大豆粉のTIは容易に失活することを認めた.焙煎丸大豆のTIも容易に熱失活するがガラス管封入大豆粉のTIの方がより容易に熱失活した.(2) 焙煎後の丸大豆,大豆粉およびガラス管封入大豆粉の残存水分を測定したところ,ガラス管封入大豆粉は密封されているために水分の蒸発乾燥はなく,従って焙煎後も焙煎前の水分が全量残存した.丸大豆は種皮や細胞膜に包まれた半密封状態であり焙煎前の約半量以上の水分が残存した.大豆粉は粉砕されているために焙煎中に水分が容易に蒸発して,残存水分は0%に近い値になった.一般にタンパク質が加熱変性するときの温度は水分が多量に存在するときは水分量の影響を受けないが,微量の場合は水分量に著しく影響を受けることから推測すると,大豆粉中のTIが焙煎法で熱失活しないのはこの微量水分が焙煎中に容易に蒸発してなくなるためではないかと思われた.(3) 水分量を段階的に調製した大豆粉をガラス管に封入した後,焙煎してTIの失活率を調べたところ,焙煎後の残存水分が少量になるのに比例してTIは熱失活しなくなることを認めた.水分0%の大豆粉を焙煎してTIを失活させるには焦げて黒変する190℃以上の高温焙煎を要した.(4) 通常の生の丸大豆は約10%の水分を含み,焙煎後も5～6%の水分が残存することが認められたので,TIを熱失活するには150℃ 20分の焙煎温度で充分目的が果たせるものと思われた.(5) 乾燥大豆粉をオートクレーブで120℃ 20分加熱する場合は,少なくとも粉の13%以上の水分が含まれるよう予め粉に加湿する必要があるものと思われた.

EFFECT of EXTRUSION ON TRYPSIN INHIBITOR CONTENTS of SOY-SWEET POTATO MIXTURES

Mixtures of soy and sweet potato (Ipomoea batatas) (L.) Lam), flours containing 18%, 25% and 30% moisture, respectively, were extruded in a single screw extruder. Results showed that inactivation of trypsin inhibitor was enhanced by both reductions in feed moisture and soy flour contents of sample mixtures. Hence subsequent extrusion was carried at 18% feed moisture with variable feed ratio, screw rotation speed and die diameter, using a central composite rotatable, near orthogonal experimental design. Results further showed that the effect of increasing the ratio of soy in the mixture was linearly significant (p > 0.05). Optimum Trypsin Inhibitor (TI) inactivation value of 3.40 mg/g was predicted at a feed composition of 80% sweet potato, 9 mm die diameter and 154 rpm, respectively.

Nutritional quality of extruded snacks developed from composite of rice brokens and wheat bran

Wheat bran was mixed with broken rice to develop nutritionally balanced extruded crisp snacks for human consumption. The inclusion of wheat bran enhanced the content of nutrients such as calcium, phosphorus, iron, copper, thiamine, riboflavin, lysine and also of antinutrients like phytic phosphorus and trypsin inhibitor. Extrusion cooking decreased the content of thiamine, riboflavin and lysine. The degradation of phytic phosphorus and inactivation of trypsin inhibitor had an improving effect on the nutritional quality of the extruded snacks as reflected by higher in vitro digestibility of its proteins.

Inactivation of Trypsin Inhibitor in Chickpea

Changes in the trypsin inhibitor activity of chickpeas were investigated after the seeds were soaked in deionized water, citric acid and sodium carbonate solutions. The effect of boiling for 30, 60, 120 and 300 s was also studied. Soaking did lower but did not remove the trypsin inhibitor activity irrespective the pH of the soaking solution. The trypsin inhibitor activity was effectively reduced on boiling the seeds in water and was totally removed after 300 s of treatment. The protein content quality of soaked and boiled seeds was nutritionally suitable.