BIOACTIVE PEPTIDES AND HEALTH EFFECTS

Bioactive peptides are organic substances formed by amino acids joined by covalent bonds known as amide or peptide bonds. Although some bioactive peptides exist free in its natural source, the vast majority of known bioactive peptides are encrypted in the structure of the parent proteins and are released mainly by enzymatic processes. Some bioactive peptides have been prepared by chemical synthesis. Bioactive peptides attributed to different health effects, including antimicrobial properties, blood pressure-lowering (ACE inhibitory) effects, cholesterol-lowering ability, antithrombotic and antioxidant activities, opioid activities, enhancement of mineral absorption and/or bioavailability, cytomodulatory and immunomodulatory effects, antiobesity, and anti-genotoxic activity. The growing interest in bioactive peptides has incentivized the scientific community and the food industry to exploring the development of new food additives and functional products based on these peptides. The present review highlights the recent findings on the identification, bioassays, and use of bioactive peptides, as well as their potential use as food additives and in the development of functional products

Effect of harvest year on biochemical properties of Narince grape (Vitis vinifera l. cv. Narince) polyphenol oxidase

Biochemical characteristics of polyphenol oxidase (PPO) from Narince grapes were studied in two consecutive years (2006 and 2007). The optimum pH and temperature of the two PPOs were found to be same (5.49 and 45 °C). The apparent substrate specificities were established from Vmax/Km as follows: caffeic acid > 4-methylcatechol > catechol > pyrogallol for two enzymes. There were marked differences between the two enzymes in terms of thermal stability. The effects of inhibitors varied in a dose-dependent manner. The degree of inhibition exerted by the inhibitors tested varied according to the harvest year. © 2013 Springer-Verlag Berlin Heidelberg.Acknowledgments This project (TÜBİTaK 106O340) was supported by the Scientific and Technical Research Council of Turkey

Altontop suyundaki acılığın naringinaz enzimi ile giderilmesi

Bu çalışmada Marsh Seedless ve Rio Red çeşiti altıntoplardan elde edilen meyve sularındaki acılığın giderilmesi araştırılmıştır. Acılık giderme işlemi farklı naringinaz konsantrasyonlarında (0.25, 0.50, 0.75 ve 1.00 g/L) ve farklı sıcaklıklarda (25, 35 ve 40oC) gerçekleştirilmiştir. Naringin giderimi, naringinaz miktarı ve sıcaklıktaki artışa paralel olarak artmıştır. Her iki çeşitte de en yüksek naringin giderimi 1 g/L naringinaz konsantrasyonunda 40oC’de ve 6 saatlik inkübasyon sonunda elde edilmiştir. Duyusal değerlendirmede panelistler kontrol örneklerini enzimle muamele edilmiş örneklerden ayırt edebilmişlerdir.This study was undertaken to investigate debittering of grapefruit juices from Marsh Seedless and Rio Red varieties. Debittering was carried out with different naringinase concentrations (0.25, 0.50, 0.75 and 1.00 g/L) at different temperatures (25, 35 and 40oC). Increasing naringinase concentration and temperature resulted in a higher naringin reduction. In both varieties, the highest naringin reduction was obtained with 1 g/L naringinase at 40oC for 6 h. The results from organoleptic evaluation showed that the panellists were able to distinguish the control samples from the enzyme-treated samples

Extraction and characterisation of pectin methylesterase from black carrot (Daucus carota L.)

This study was carried out to determine some of the biochemical properties of pectin methylesterase (PME) from black carrot. The enzyme showed very high activity in a broad pH range of 6.5-8.5, with the optimum pH occurring at 7.5. The optimum temperature for maximal PME activity was found to be 55 °C. NaCl enhanced PME activity, particularly at 0.2 M. Km and Vmax values for black carrot PME using apple pectin as substrate were found to be 2.14 mg/ml (r2 = 0.988) and 3.75 units/ml, respectively. The enzyme was stable between the temperatures of 30-50 °C/5 min whereas it lost nearly all of its activity at 70 °C/5 min. Ea and Z values were found to be 196.8 kJmol-1 (r2 = 0.996) and 2.16 °C (r2 = 0.995), respectively. © 2009 Elsevier Ltd. All rights reserved.This study (ZF2006.YL.84) was funded by the Research Fund of the University of Cukurova, Turkey

Characterization of Sultaniye grape (Vitis vinifera L. cv. Sultana) polyphenol oxidase

Polyphenol oxidase (PPO) was extracted from Sultaniye grapes grown in Turkey, and its characteristics in terms of pH and temperature optima, thermal inactivation, kinetic parameters and potency of some PPO inhibitors were studied. Optimum pH and temperature for grape PPO were found to be 3.4 and 30 °C, using catechol as substrate. Km and Vmax values were found to be 44.5 ± 5.47 mm and 0.695 ± 0.0353 OD410 min-1, respectively. Four inhibitors were tested in this study and the most potent inhibitor was sodium metabisulphite, followed by ascorbic acid. From the thermal inactivation studies in the range of 65-80 °C, the half-life values of the enzyme ranged between 2.6 and 49.5 min. Activation energy (Ea) and Z values were calculated to be 208.5 kJ mol-1 (r2 = 0.9544) and 10.95 °C (r2 = 0.9517), respectively. © 2007 The Authors. Journal compilation 2007 Institute of Food Science and Technology Trust Fund

Domat zeytini polifenol oksidazının biyokimyasal özelliklerinin belirlenmesi

Zarar görmüş meye ve sebzelerdeki enzimatik esmerleşme fenolik bileşiklerin oksidasyonu sonucu meydana gelir ve önemli kalite kayıplarına neden olur. Esmerleşme reaksiyonuna neden olan en önemli enzim polifenol oksidaz (PFO)’dır. Domat zeytininden polifenol oksidaz enzimi ekstrakte edilmiş ve amonyum sülfat çökeltmesi, dializ ve iyon değişim kromatografisi ile saflaştırılmıştır. Zeytin PFO’sunun optimum pH ve sıcaklığı sırasıyla 4-metil kateflol substratı kullanılarak 4.5 ve 30 °C bulunmuştur. Zeytin PFO’su Km ve Vmax değerleri sırasıyla 4-metil kateflol substratı kullanılarak 14.52 mM (r2= 0.985) ve 1.78 Abs/dak bulunmuştur. Test edilmiş inhibitörlerin en etkili olanları sistein ve sodyum disülfittir. Bu çalışmada elde edilmiş Z ve Ea değerleri sırasıyla 18.6 °C (r2 = 0.953) ve 121.0 kj/mol (r2= 0.950) bulunmuştur.Enzymatic browning of damaged tissues of fruits and vegetables occurs from the oxidation of phenolic compounds and contributes significantly to quality loss. The primary enzim responsible for the browning reaction is polyphenol oxidase (PPO). PPO from Domat olives was extracted and purified through (NH4)2SO4 precipitation, dialysis and ion exchange chromatography. Optimum pH and temperature for olive PPO were found to be 4.5 and 30 °C, respectively, using 4-methyl catechol as substrate. Km and Vmax values for olive PPO using 4-methyl catechol as substrate were found to be 14.52 mM (r2= 0.985) and 1.78 Abs/min, respectively. Of the inhibitors tested, the most potent inhibitors were L-cysteine and sodium disulfite. The Z and Ea values obtained in this study were 18.6 °C (r2 = 0.953) and 121.0 kj/mol (r2= 0.950), respectively

Sıcaklığın karbonhidrantların anaerobik giderimine etkisi

Nişasta, glikoz vefrüktoz içeren model atıksularm kesikli kültürde anaerobik giderimi mezofılik ve kış çevre sıcaklığında araştırılmıştır. Mezofilik sıcaklıkta karbonhidrat giderimi daha hızlı gerçekleşmiştir. Ortam sıcaklığında gerçekleştirilen denemelerde uçucu yağ asitleri birikimi daha fazla olmuştur. Sıcaklığın uçucu asit birikimi ve biyogaz verimine etkisi istatistiksel olarak önemli bulunmuştur. Sonuçlar anaerobik arıtımın düşük sıcaklıkta da gerçekleştirilebileceğini göstermektedir.Anaerobic digestion of model wastewaters containing starch, glucose and fructose was investigated in batch culture at mesophilic and ambient temperature during winter. Carbohydrate utilisation was faster at mesophilic temperature. A higher VFA accumulation was observed at ambient temperature. Effect of temperature on VFA accumulation and biogas yield was found to be statistically significant. The results indicate that anaerobic digestion can also be performed at lower temperatures