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Öğe ACE-inhibitory activities of peptide fractions (<3 kDa) and identification of peptide sequence by MALDI-ToF-MS in model cheeses incorporating different Lactobacillus species(Academic Press Inc Elsevier Science, 2022) Sahingil, D.; Gokce, Y.; Celikbicak, O.; Hayaloglu, A. A.In this study, the effects of five adjunct lactobacilli on the formation of angiotensin-converting enzyme inhibitory (ACE-i) peptides in model cheeses were investigated. A total of seven peptide fractions (less than 3 kDa) were obtained by means of a fraction collector coupled with a HPLC system. ACE-i activity and peptide sequence analysis of the seven fractions were determined by RP-HPLC and then MALDI-ToF-MS techniques, respectively. Peptides produced from alpha s1- and kappa-caseins had higher amounts compared to those produced by other caseins. There were considerable differences between the fractions in terms of peptide sequences and ACE-i activities. In general, the peptide fraction containing Lactobacillus delbrueckii ssp. bulgaricus exhibited a higher level of ACE-i activity (79.56%) than the other samples. The next highest ACE-i activity was determined in the cheese containing L. plantarum and significant differences were observed between the ACE-i activities of the fractions. The highest ACE-i activity was identified in fractions including f1 (51.39%) for L. casei, f6 (33.49%) for L. helveticus, f4 (46.62%) for L. helveticus DPC4571 and f1 (47.96%) for cheese containing non-adjunct culture. In conclusion, use of lactobacilli as an adjunct in model cheese increased the peptide types and amounts and also ACE-i activity.Öğe An alternative plant-based fermented milk with kefir culture using apricot (Prunus armeniaca L.) seed extract: Changes in texture, volatiles and bioactivity during storage(Elsevier Sci Ltd, 2022) Uruc, K.; Tekin, A.; Sahingil, D.; Hayaloglu, A. A.The aim of the study was to produce kefir from apricot seed extract (ASE) as an alternative functional dairy food for vegans and lactose-intolerant people, the elderly, people with cardiovascular disease and diabetes. Kefir was produced by using cow's milk (100%, as control) and 100% ASE, and cow's milk was mixed with 25%, 50% and 75% (v/v) with ASE for kefir production and the resultant kefir samples were stored at 4 degrees C for 21 days. In proportion to the level of ASE, more yellowish color, lower viscosity, firmness, consistency and TPA values were developed. Additionally, a higher syneresis was observed in kefir samples with increasing levels of ASE. Angiotensin-converting enzyme-inhibitory (ACE-i) and antioxidant activities increased with the increasing levels of ASE used in the kefir production. The levels of individual free amino acids significantly changed by use of ASE and some amino acids including Gln, Gly and Arg dramatically increased, while others decreased by increasing levels of the ASE. Relatively lower levels of gamma-amino butyric acid (GABA) were observed in the samples when compared to the free amino acids, and its concentration decreased by increasing levels of the ASE. The counts for yeasts, lactobacilli and lactococci increased with addition of ASE. Qualitative and quantitative differences were seen in volatile composition of kefir with the addition of ASE and acceptable sensory scores were obtained for all samples during storage. Concentrations of carboxylic acids decreased with increasing levels of ASE in kefir formula; however, the levels of alcohols and aldehydes increased. In conclusion, ASE can be considered in the formulation of fermented milk products or used purely in the production of plant-based fermented non-dairy beverages.Öğe Changes in volatile composition and sensory properties of Iranian ultrafiltered white cheese as affected by blends of Rhizomucor miehei protease or camel chymosin(Elsevier Science Inc, 2016) Soltani, M.; Sahingil, D.; Gokce, Y.; Hayaloglu, A. A.The effect of using various combinations of Rhizomucor miehei protease and camel chymosin (100:0, 75:25, 50:50, 25:75, and 0:100, respectively) on volatile composition and sensory scores in Iranian ultrafiltered white cheese was studied during 90 d of ripening. A solid-phase microextraction-gas chromatography-mass spectrometric method was used for determining the volatile compounds of the cheeses. Forty compounds including esters (12), acids (6), ketones (9), alcohols (3), and miscellaneous compounds (10) were identified. The main classes of volatile components in the cheeses are esters, miscellaneous compounds, and ketones. The type and concentration of the coagulants influenced both volatile composition and sensory scores of the cheeses. Principal component analysis separated the cheeses based on the use of 2 coagulants in various combinations and ripening time. The cheeses produced using higher concentrations of R. miehei were separately located on the plot compared with the cheeses produced using higher concentrations of camel chymosin. Sensory evaluation of the cheeses showed that, in general, the cheeses produced using higher concentrations of camel chymosin received higher body and texture and odor and flavor scores than the cheese produced using higher concentrations of R. miehei. In conclusion, 2 combinations of R. miehei and camel chymosin (75:25 and 25:75, respectively) can be successfully used for the production of Iranian ultrafiltered white cheese, considering the results of volatile composition and sensory analysis.Öğe Characterizing volatile compounds and proteolysis in Gokceada artisanal goat cheese(Elsevier, 2013) Hayaloglu, A. A.; Yasar, K.; Tolu, C.; Sahingil, D.The objective of the study was to determine the gross composition, proteolysis and volatile compounds in Gokceada goat cheese and to provide initial information on its manufacturing and ripening processes. Gokceada goat cheese is traditionally manufactured from raw goat milk in Gokceada (Imbros) island, Canakkale, Turkey. In the present study, 23 commercial samples were characterized. Urea-polyacrylamide gel electrophoresis of the water-insoluble fractions showed that both alpha(s)- and beta-caseins were extensively decomposed, but beta-casein was less degraded compared to alpha(s)-casein. RP-HPLC of peptide profiles in the water-soluble fractions demonstrated qualitative and quantitative differences among the samples. Sixty volatile compounds were identified by SPME/GC-MS technique with alcohols and esters as the principal class of volatile components in the cheeses. In general, relatively large variability in gross composition and concentration of volatile aroma was found, which probably reflects lack of standardization in the production of the cheese. (C) 2013 Elsevier B.V. All rights reserved.Öğe Determination of the effects of proteolysis-based changes by adjunct lactobacilli on the bioactivity (ACE-inhibitory and antioxidant activities) of cheese: a model cheese study(Springer India, 2024) Sahingil, D.; Gokce, Y.; Hayaloglu, A. A.Bioactive properties, proteolysis and microbiology of model cheeses with and without adjunct lactobacilli (Lactobacillus helveticus, Lactiplantibacillus plantarum, Lactobacillus bulgaricus and L. casei) were studied during 120 days of storage at 8 or 16 C-degrees. Bioactive properties were observed in peptide fractions (< 3 kDa, 3-10 kDa, < 10 kDa) separated using ultrafiltration membranes. Antioxidant activity of these fractions was determined by radical scavenging assays as ABTS [2, 2 ' -azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)]. Angiotensin-converting enzyme-inhibitory (ACE-i) activity (% and IC50) and peptide profiles of 70% ethanol-soluble and -insoluble fractions were determined by RP-HPLC. Use of lactobacilli as an adjunct culture significantly changed the RP-HPLC peptide profiles of the cheeses; however, slight changes were observed in the patterns of urea-polyacrylamide gel electrophoresis. Fractions smaller than 3 kDa had higher ACE-i and antioxidant activities for all cheese samples. In conclusion, this study indicates that the addition of lactobacilli as an adjunct culture contributed to the formation of bioactive compounds in the model cheeses and also changed the proteolysis levels.Öğe Enrichment of antioxidant activity, phenolic compounds, volatile composition and sensory properties of yogurt with rosehip (Rosa canina L.) fortification(Elsevier, 2022) Sahingil, D.; Hayaloglu, A. A.Total phenolic content, pH, color, total antioxidant activity and volatile compounds in yogurt fortified [5-20%] with rosehip (Rosa canina L.) were identified in the present study. Rosehip addition caused a proportional increase in the levels of total phenolics. Fifty-three volatile compounds were identified using the gas chromatographic method, and the major volatiles were carboxylic acids including acetic, butanoic, hexanoic and octanoic acids. After sensory evaluation, yogurt with 20% rosehip pulp added scored highest for overall acceptability. The use of rosehip pulp positively contributed to quality parameters such as water holding capacity, antioxidant capacity and phenolic contents, and contributed to volatile profile and sensory attributes of yogurt. Consuming yogurt with rosehip pulp could provide prebiotics for probiotic bacteria and contribute to the antioxidant activity of yogurt. Furthermore, it may enhance polyphenols with the potential to exert synergistic effects on human health.Öğe Optimization of proteolysis and angiotensin converting enzyme inhibition activity in a model cheese using response surface methodology(Elsevier Science Bv, 2019) Sahingil, D.; Gokce, Y.; Yuceer, M.; Hayaloglu, A. A.Adjunct cultures including lactobacilli play important role in cheese proteolysis and bioactivity including Angiotensin Converting Enzyme (ACE)-inhibition and antioxidant activity. Four species of lactobacilli was used in the manufacture of model cheese and these were salted at different levels and the resultant cheeses were ripened at different time and temperature to understand the effect of salting and ripening conditions. The effects of the use of various of lactobacilli (Lactobacillus casei, Lb. helveticus, Lb. delbrueckii ssp. bulgaricus and Lb. plantarum), salt concentrations (1, 2, 3, 4 and 5%), ripening times (1, 30, 60, 90 and 120 days) and temperatures (5, 10, 15 and 20 degrees C) were investigated. The experiments were designed to determine the optimal salt concentration, ripening times and temperatures for optimal proteolysis, the highest levels of ACE-inhibition and antioxidant activity. The highest level of proteolysis and ACE-inhibiting activity in the model cheese was observed when ripening temperatures were between 8 and 16 degrees C, salt concentration at 2.5-3.0% and with a ripening period of about 60 days. The use of each lactobacilli contributed to the proteolysis in different manner; for example, ACE-inhibiting activity and antioxidant activity in the model cheese.Öğe Volatiles and sensory evaluation of goat milk cheese Gokceada as affected by goat breeds (Gokceada and Turkish Saanen) and starter culture systems during ripening(Elsevier Science Inc, 2013) Hayaloglu, A. A.; Tolu, C.; Yasar, K.; Sahingil, D.The effect of goat breed and starter culture on volatile composition and sensory scores in goat milk cheese was studied during 90 d of ripening. Milk from 2 goat breeds (Gokceada and Turkish Saanen) and different starter culture systems (no starter, mesophilic and thermophilic starters) were used in the manufacture of goat milk cheeses (called Gokceada goat cheese). Volatile composition was determined by a solid-phase microextraction gas chromatography-mass spectrometric method. Sixty compounds including esters (13), carboxylic acids (7), aldehydes (6), ketones (8), alcohols (14), and miscellaneous compounds (12) were identified. Esters, alcohols, and carboxylic acids were the main classes of volatile components in the cheeses. Both qualitatively and quantitatively, the use of different starter cultures and goat breeds significantly influenced the volatile fraction of goat milk cheese. Decanoic, hexanoic, and octanoic (commonly named capric, caproic, and caprylic) acids were indicator compounds to distinguish the goat breeds. Principal component analysis grouped the cheeses based on the use of starter culture and goat breed. Starter-free cheeses were separately located on the plot and age-related changes were present in all samples. Sensory evaluation of 90-d-old cheeses showed that the cheeses from the Gokceada breed received higher odor, flavor, and quality scores than those from the Turkish Saanen breed, and cheeses made using mesophilic starters resulted in the most satisfactory scores for flavor and quality attributes. In conclusion, goat milk cheeses made using milk from Gokceada goats and mesophilic starter culture had the best quality in terms of volatile composition and sensory attributes.
