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Öğe Bazı doğal antioksidanların yer fıstığı yağının kızartma kalitesi üzerine etkileri(Çanakkale Onsekiz Mart Üniversitesi, 2012) Aydeniz, Buket; Yılmaz, EminBu araştırmada taze çay yaprağı, üzüm çekirdeği ve domatesten elde edilen fenolik ekstraktlar ile pirinç kepeğinden ekstrakte edilen saf ?-oryzanol rafine yerfıstığı yağına antioksidan katkı olarak uygulanmış ve gerçek kızartma koşullarındaki (180°C, 7 gün, 5h/gün) etkinliği araştırılmıştır. Bu bitkisel kaynaklar, bütillendirilmiş hidroksi anisol (BHA) ve bütillendirilmiş hidroksi toluen (BHT) gibi yaygın sentetik antioksidanlar ile karşılaştırılmıştır. Böylece bu ekstraktların termal oksidasyonu önleme potansiyelleri ve kızartma yağlarında kullanım olanakları ortaya çıkarılmıştır. Ayrıca kızartılan hamurların duyusal özellikleri de ölçülerek tüketime uygunlukları belirlenmiştir.Genel olarak, yararlanılan tüm doğal antioksidanların yağın kullanım ömrünü önemli derecede artırdığı ve yağ stabilitesini yükselttiği tespit edilmiştir. Ayrıca hamurlarda kontrole göre herhangi bir duyusal farklılık da bulunamamıştır.Tüm deneme gruplarında yapılan ölçümlerden elde edilen sonuçların aralıkları şöyledir; toplam polar madde-kromatografi (% 10,72-73,80), toplam polar madde ? prob (% 14,52-88,50), serbest asitlik (% 0,090-2,903), dumanlanma noktası (233,50-168,35 oC), konjuge dieonik asit (% 0,01-0,40), L değeri (52,68-41,42), a* değeri (3,41-5,26), b* değeri (-5,30-10,46), bulanıklık (0,70-10,40 NTU), viskozite (69,57-442,00 cP), toplam fenolik içeriği (0,36-4,20 mg GA/100g yağ), antioksidan kapasite (0,53-11,00 mmol Trolox/100g yağ) ve hamurların adsorbe ettiği yağ miktarı (% 3,62-14,22) olarak ölçülmüştür. Kızartmanın son günündeki yağ örneklerinde analiz edilen yağ asiti ve sterol kompozisyonları incelendiğinde, doğal antioksidanlar ile katkılamanın doymamış yağ asitleri oksidasyonunun engellenmesi ve linoleik asite kıyasla özellikle oleik asitin stabilitesinin sağlanmasında etkin rol oynadığı, özellikle yeşilçay ekstraktı ile katkılanmış deneme grubunun yaygın steroller bakımından daha zengin bir içeriğe sahip olduğu tespit edilmiştir.Sonuç olarak, yerfıstığı yağının termal stabilitesi üzerine likopen ve yeşilçay ekstraktlarının olumlu sonuçlar verdiği, fenol içeriği ve antioksidan kapasite bakımından ise ?-oryzanol'ün başarı sağladığı tespit edilmiştir. Buna göre doğal antioksidanların hem yağın bozulmasının engellenmesi hem de kızartılan gıdanın kalite özelliklerinin iyileştirilmesi üzerinde pozitif etkilere sahip oldukları saptanmıştır. Gıda güvenliği açısından sorun taşımayan, üründe duyusal açıdan avantajlar bile oluşturan doğal antioksidan ekstraktlarının kızartma yağlarında da güvenle kullanılabileceği önerilmiştir.Anahtar Kelimeler: Derin-yağda kızartma, taze çay yaprağı, üzüm çekirdeği, domates, ?-oryzanol, ekstrakt, oksidasyon, antioksidan kapasite.Öğe Cold pressed capia pepperseed (Capsicum Annuum L.) oils: Composition, aroma, and sensory properties(Wiley, 2015) Yılmaz, Emin; Arsunar, Emel Sevgi; Aydeniz, Buket; Guneser, OnurIn this study, cold press-produced capia pepperseed oil samples were characterized. Pre-roasting and enzyme treatment against control group (no pre-treatment) were applied to the seeds prior to cold pressing, and the oil yield, meal, and oil quality parameters were examined. The physico-chemical parameters (refractive index, viscosity, turbidity, specific gravity, color, free acidity, peroxide and iodine values, antioxidant capacity, total phenolic content, and energy value), components composition (fatty acid, sterol, and tocopherol), thermal parameters (melting and crystallization temperatures and enthalpies), volatile aromatics composition, sensory properties (Flavor Profile Analysis), and consumer perception (hedonic test) of the oil samples were accomplished. It was found that cold pressing is low in efficiency, and oil sensory quality and consumer acceptability levels were also low. Although pre-roasted seeds yielded a little more oil and had better sensory quality, it was determined that these oils need at least a deodorization or a physical refining for acceptable sensory quality. Practical applications: The results of this study indicated that capia pepperseeds obtained as waste during vegetable processing can be used as an alternative source for cold pressed oils and a raw material for animal feed. Moreover, these seed oils have economical impact due to their essential fatty acid (linoleic acid, 71.13%), sterol, and tocopherol content. Based on the sensory findings, full or partial refining is recommended in order to increase the sensory quality of the pepperseed oil.Öğe Determining Frying Oil Degradation by Near Infrared Spectroscopy Using Chemometric Techniques(Wiley, 2012) Ogutcu, Mustafa; Aydeniz, Buket; Buyukcan, Mehmet Burak; Yılmaz, EminA rapid method for the determination of some important physicochemical properties in frying oils has been developed. Partial least square regression (PLS) calibration models were applied to the physicochemical parameters and near infrared spectroscopy (NIR) spectral data. PLS regression was used to find the NIR region and the data pre-processing method that give the best prediction of the chemical parameters. Calibration and validation were appropriated by leave one out cross validation and test set validation techniques for predicting free fatty acids (FFA), total polar materials (cTPM; measured by chromatographic method and iTPM measured by an instrumental method), viscosity and smoke point of the frying oil samples. For PLS models using the cross validation techniques, the best correlations (r) between NIR predicted data and the standard method data for iTPM in oils were 93.79 and root mean square error of prediction (RMSEP) values were 5.53. For PLS models using the test set validation techniques, the best correlations (r) between NIR predicted data and standard method data for FFA, cTPM, viscosity and smoke point in oils were 92.58, 94.61, 81.95 and 84.07 and RMSEP values were 0.121, 3.96, 22.30 and 8.74, respectively. In conclusion, NIR technique with chemometric analysis was found very effective in predicting frying oil quality changes.Öğe Effects of roasting and enzyme pretreatments on yield and quality of cold-pressed poppy seed oils(Tubitak Scientific & Technological Research Council Turkey, 2015) Emir, Dilek Dundar; Aydeniz, Buket; Yılmaz, EminThe aim of this study was to compare the effects of roasting and enzyme pretreatments on the yield and quality of cold-pressed oils obtained from 3 poppy seed varieties (Ofis 3 (blue), Ofis 4 (yellow), Ofis 8 (white)). The oil recovery range was 21.89%-38.36% with cold pressing. The oily cakes (meal) contained 42-168 g/kg oil and 113-166.3 g/kg moisture after the cold pressing. Physicochemical and quality tests were conducted to evaluate and compare the efficacy of the pretreatments. Furthermore, fatty acid, sterol, and tocopherol compositions were determined. Oil recovery was enhanced by enzyme treatment in Ofis 3 (28.31%) and Ofis 8 (38.36%), while roasting enhanced oil yield in Ofis 4 (29.36%) samples. On the other hand, enzyme treatment caused some problems, like increases in free acidity and peroxide value. The other physicochemical properties and minor components of the oils were not significantly affected by the pretreatments. Furthermore, it was determined that the oily cakes can be a good source of protein. This study proved that higher quality poppy seed oil can be produced with acceptable yield by applying the cold pressing technique coupled with a preroasting process.Öğe Enrichment of frying oils with plant phenolic extracts to extend the usage life(Wiley, 2012) Aydeniz, Buket; Yılmaz, EminThe aim of this research was to evaluate the efficacy of extracts prepared from olive leaf (OLVL), hazelnut leaf (HAZL), and hazelnut green leafy cover (HGLC) in frying conditions. The extracts were added into canola oil at 200?ppm phenolic equivalence level and fried for seven consecutive days and analyzed. Generally, the lowest phenolic content and antioxidant capacity value were measured in HGLC extract, although, the best performance during frying was with HGLC extract. There were significant differences among the free acidity, conjugated dienoic acids, and total polar materials (TPM). The oil enriched with HGLC extract did not exceed the limit TPM value at the end of seventh day. Also the remaining antioxidant capacities in the frying oil samples were highest in HGLC enriched samples. The viscosity and turbidity values of the oils enriched with OLVL and HAZL extract were a little higher than a control sample. Generally trans-fatty acid formation was lower in the enriched oil samples. Also significant decreases in the level of unsaturated fatty acids during frying period were observed. This study shows that enriching oils with easily found and cheap natural plant extracts can extend their usage life. Practical applications: The results of this study have shown that liquid frying oils can successfully be enriched with plant phenolic extract to enhance thermo-oxidative stability. Addition of phenolic extract up to 200?ppm level have not created any problem in sensory quality of either the oil or fried dough. The HGLC and OLVL extract were found very suitable for this purpose. These materials are common agro-food by-products and can be produced very easily with low cost. Also, this type of enrichment may aid consumers to get some beneficial phenolic compounds through fried food consumption. In addition, these types of applications may open another area for marketing the named plant extracts.Öğe Performance of Different Natural Antioxidant Compounds in Frying Oil(Faculty Food Technology Biotechnology, 2016) Aydeniz, Buket; Yılmaz, EminIn this study, the natural green tea extract, purified lycopene, purified resveratrol and purified gamma-oryzanol were added into peanut oil and their antioxidant performances were evaluated during frying. Moreover, the sensory properties of fried dough were evaluated to determine the consumption feasibility. All natural antioxidants led to significant increase in the stability of the oil samples. The ranges of measurements in the treatment groups were as follows: free acidity 0.1-2.9 g of oleic acid per 100 g of oil, conjugated dienes 0.01-0.40 g per 100 g of oil, total polar material 8.8-73.8 g per 100 g of oil, total phenolics 0.1-4.2 mg of gallic acid equivalents per 100 g of oil, and antioxidant capacity 0.5-11.0 mM of Trolox equivalents per 100 g of oil. The fatty acid and sterol compositions indicated that antioxidant supplementation could slow the oxidative degradation of unsaturated fatty acids and reduce trans-acid formation. Frying oil enriched with purified gamma-oryzanol had higher sterol levels than the other enriched oil samples. The obtained quality of oil protection was in descending order: purified gamma-oryzanol, green tea extract and purified lycopene.Öğe Physico-chemical, Sensory and Aromatic Properties of Cold Press Produced Safflower Oil(Springer, 2014) Aydeniz, Buket; Guneser, Onur; Yılmaz, EminIn this study, seeds from the safflower variety called Din double dagger er were roasted and microwaved before oil extraction by cold pressing. Some physico-chemical analyses (moisture, ash, oil content and color) were performed in safflower meals. Physico-chemical properties (refractive index, viscosity, turbidity, specific gravity, color, free acidity, peroxide value, iodine number), nutritional components (total phenolics, antioxidant capacity, tocopherol content), sterol composition and fatty acid composition of produced oils were also determined. Volatile components of the oils were detected by solid-phase microextraction/gas chromatography-mass spectrometry technique. Quantitative descriptive analysis was accomplished with trained panelists by 11 definition terms. Cold pressing yielded less oil than solvent extraction, but oil quality was superior and a refining process was not required. There was no significant difference between samples for fatty acid composition and some physico-chemical parameters. Whereas, microwave treatment caused a decrease in oil turbidity, free acidity, alpha-tocopherol and some sterol contents and an enhancement in total phenolic content, antioxidant capacity and peroxide value. Moreover, microwave treatment led to an increased nutty aroma in the oil. In contrast, isot pepper aroma was decreased by microwave treatment. This study provides very important information about the safflower oils for the first time in the literature.Öğe Phytostanol Supplementation Through Frying Dough in Enriched Canola Oil(Wiley, 2013) Aydeniz, Buket; Yılmaz, EminThe objectives of this study were to determine a suitable level of phytostanols for addition to canola oil and to investigate the performance of the supplemented oil during frying. The frying oil was supplemented with 5, 10, 15, 20 % w/w phytostanols and two suitable levels (5 and 10 %) were selected. Dough frying was performed for 5 consecutive days at 180 degrees C for 5 h/day. The ranges of analytical measurements in the treatment groups were; free acidity (0.12-10.07 %), conjugated dienes (0.47-1.37 %), total polar material with probe (9.00-51.25 %), viscosity (46.27-195.51 cP), turbidity (0.82-1.80 NTU), and smoke point (202.75-274.25 degrees C). The results indicated that 5 % phytostanol enriched oil was superior in terms of oil stability and sensory quality of the fried dough among all the enriched oils. Samples with 10 % added phytostanols were high in free acidity, conjugated dienes and smoke points. Sterol composition analysis showed that the fried dough absorbed total sterols of 49.9 and 95 g/kg in 5 and 10 % supplemented oils, respectively. Hence, some health benefits could be achieved through consuming products which have been fried in phytostanol supplemented canola oil.Öğe Sensory and Physico-Chemical Properties of Cold Press-Produced Tomato (Lycopersicon esculentum L.) Seed Oils(Wiley, 2015) Yılmaz, Emin; Aydeniz, Buket; Guneser, Onur; Arsunar, Emel SevgiIn this study, roasted and unroasted (control) tomato seeds were cold pressed and the seeds, oils, and seed presscakes (meals) were analyzed. Some physicochemical properties, total phenolic content and antioxidant capacity, thermal properties, mineral contents, fatty acids, sterols and tocopherols compositions, volatile compounds and sensory evaluation of the tomato seed oils were determined. The tomato seeds contained 3.3 % of ash, 17.3 % of oil and 27.2 % of protein. The cold press oil recovery rate was 7.2 and 10.28 % for control and roasted seeds, respectively. There were eight sensory terms defining the oils together with 34 different aromatic compounds quantified. The volatile compounds furfural, hexanal, benzaldehyde and 2-isobutylthiazole were found with the highest frequency in the samples. Roasted, green and tomato were defined as characteristic sensory terms for tomato seeds oils. Fifteen different minerals, melting and crystallization temperatures and enthalpies of the oil samples were also quantified. This study provides important data for the tomato seed oils, and proves that pre-roasted tomato seed oils are high quality, nutritious and aromatics oils with higher levels of consumer acceptability.Öğe Sensory evaluation and consumer perception of some commercial green table olives(Emerald Group Publishing Ltd, 2012) Yılmaz, Emin; Aydeniz, BuketPurpose - The objective of this study is to evaluate the physico-chemical and sensorial characteristics of some commercial green table olives. Also,. it seeks to elaborate the sensorial background of consumer preferences of different green table olives. Design/methodology/approach - Four green table olive samples (Celebi, Domat, Kaba, and Ayvalik) commonly consumed in Turkey were chosen and collected from a local producer. Dimensional measures, salt content, pH value, oil content, titrable acidity, L value, a* value, b* value and texture of samples were assessed by the AOAC methods. A panel described and measured the appearance (greenness, yellowness, globeness), aroma (fresh olive, vinegary, soapy, musty), flavour (sour, salty, bitter, hay, oily) and texture properties (firmness, flesh/stone adherence, fibrousness, watery). In addition, 50 consumers evaluated hedonic values. Findings - The salt content, pH value, oil content, titrable acidity, L value, a value, b* value and texture of samples were found to following values 2.91-5.46 percent, 2.80-3.97, 4.67-18.71 percent, 0.59-1.40 percent, 49.96-69.56, 1.35-17.91, 19.57-45.47 and 434.1-895.7 g. Although prepared with the same technique, many properties of the olives were found different. This difference affected consumer preference and buying intentions as well. Research limitations/implications - The paper provides scientific data for researchers to design similar sensory descriptive analyses for different table olive samples. Originality/value - The paper is helpful both to consumers and traders to determine the proximate and sensory attributes of commercial green olive samples.
