Farklı Yöre Zeytinlerinden Elde Edilen Naturel Zeytinyağlarının Duyusal Kalitesinin Belirlenmesi
Farklı Yöre Zeytinlerinden Elde Edilen Naturel Zeytinyağlarının Duyusal Kalitesinin Belirlenmesi
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Tarih
19.07.2013
Yazarlar
Arucu, Damla
Süreli Yayın başlığı
Süreli Yayın ISSN
Cilt Başlığı
Yayınevi
Fen Bilimleri Enstitüsü
Institute of Science and Technology
Institute of Science and Technology
Özet
Zeytinyağının, iyi kalitede, taze, olgun meyveden, presleme, santrifüjleme ve süzme ile mekanik olarak elde edilmesi ve meyvenin kendine özgü özellikleri, tüm bitkisel yağlar arasında rafinasyona bağlı tutulmadan yenebilen hemen hemen tek yağ özelliğini vermektedir. Akdeniz ülkelerinde zeytinyağı tüketimin yüksek olması dolayısıyla, koroner kalp hastalığına, diyabete, bazı kanser çeşitlerine yakalanma olasılığının düşük olması, zeytinyağına olan bakış açısını değiştirmiştir. Ancak zeytinyağlarının, sağlık üzerine pozitif etkilerini sürdürebilmesi için işlenmesi sırasında ve sonrasında doğallığını koruyabilmesi gerekmektedir. Bu sebeple zeytinyağı kalitesini etkileyen faktörler incelendiğinde öncelikli olarak zeytinin çeşidi, yetiştiği bölge, hasat zamanı, işleme aşamaları gelmektedir. Kaliteyi koruyabilmek için fiziksel, kimyasal ve duyusal özelliklerin incelenmesi ve ülke bazında karakterizasyonun sağlanması gerekmektedir. Hem üretici hem de tüketici konumunda olan ülkemizde bu açıdan pek fazla çalışma bulunmamaktadır. Çalışmada, Kuzey Ege, Güney Ege, Akdeniz, Güneydoğu Anadolu bölgeleri ve İzmir Yarımadasında üretilen natürel zeytinyağlarının fizikokimyasal ve duyusal profilini belirlemek ve bu sayede Türk zeytinyağlarına özgün bölgesel karakterizasyonu hedeflenmiştir. Ayrıca literatürdeki Türk zeytinyağlarına ilişkin bilgi eksikliğin giderilerek bölgesel tanıtım sağlanması ve hem üreticiler için hem de sonradan yapılacak çalışmalar için bakış açısı kazandırılacaktır. Bu araştırmada analiz edilen 30 adet natürel zeytinyağı, Kuzey Ege, Güney Ege, Akdeniz, Güneydoğu Anadolu bölgeleri ve İzmir Yarımadası olmak üzere beş farklı yerden, 2011 yılı Kasım ve Aralık aylarında bizzat yerel üreticilerden toplanan zeytinyağı örnekleri, zeytinlerden üç faz ve iki faz santrifüj sistemlerle elde edilmiştir. Natürel zeytinyağlarının kalite özelliklerin değerlendirilmesi için serbest yağ asitliği, peroksit değeri, toplam fenol, ultraviyole ışığında özgül soğurma, renk analizleri gerçekleştirilmiştir. 30 adet natürel zeytinyağı örneğinin, duyusal değerlendirmesinde, Uluslararası Zeytinyağı Konseyi’ nin önerdiği teknik, standart kantitatif tanımlama analizi testi ile geliştirilerek uygulanmıştır. Serbest yağ asitliği, peroksit değeri, ultraviyole ışığında özgül soğurma değerleri tebliğler dikkate alınarak analizlenmiştir. Toplam fenolik madde analizi gerçekleştirilirken, spektrofotometrik yöntem kullanılmış, renk değerleri analizlenirken tintometrede metodu uygulanmıştır. Duyusal analiz, uluslararası akreditasyona sahip, 28-50 yaşları arasındaki panelistler tarafından sabah ve akşam 4’er örnek tatmak üzere gerçekleştirilmiştir ve sonuçlar örümcek ağı diyagramları ile gösterilmiştir. Ayrıca duyusal analizi gerçekleştirilen natürel zeytinyağları, medyan değerlerine göre derecelendirilmiştir. Hesaplanan fiziksel, kimyasal ve duyusal analiz sonuçlarının birbiri üzerine korelasyonları, Spearman korelasyonu ile ölçülmüştür. Analiz edilen natürel zeytinyağlarının bölgesel açıdan değerlendirilmesinde, serbest yağ asitliği, peroksit değeri, ultraviyole soğurma değerlerinin limitleri aşmadığı tespit edilmiştir. Spektrofotometrik metodla analizlenen toplam fenol miktarının 50.86-1000.1 arasında bulunduğu, bölgesel açıdan İzmir Yarımadasının diğer bölgelere göre, fenolik madde içeriği bakımından farklı olduğu, L, a, b değerleri açısından, L değerleri (-4) - (+69.61), a değerleri (-5)-(+7.84), b değerleri ise 2-110.2 değerleri arasında, klorofil-a içeriği 0,52-6,92 ppm ve beta-karoten içeriği ise 0,09-0,86 ppm arasında değişim gösterdiği saptanmıştır. İstatistiksel açıdan serbest yağ asitliği, peroksit değeri, toplam fenol, ultraviyole ışığında özgül soğurma değerlerinin, çeşit, yetiştirilen bölge, hasat durumu, işleme yöntemi açısından farklılık göstermediği tespit edilmiştir (p>0.05). Sadece işleme yöntemleri açısından peroksit değerleri arasındaki fark (p< 0.01) ve yetiştirilen bölge ve işleme yöntemleri açısından toplam fenol değerleri arasındaki fark önemli bulunmuştur(p<0.01; p<0.05). Yetiştirilen bölge açısından, L değerleri ve b değerlerinin kendi arasındaki fark, istatistiksel olarak önemli görülürken (p< 0.01), a değerleri üzerinde işleme yönteminin etkili olduğu belirtilmiştir (p<0.01). Renk ölçülerinden klorofil-a ve β-karoten değerlendirildiğinde, klorofil-a değerleri arasındaki farkın hasat durumundan etkilendiği (p<0.05) ve β-karoten değerlerinin de yetiştirilen bölgeye göre farklılık gösterdiği saptanmıştır (p< 0.05). Natürel zeytinyağlarının meyvemsilik, acılık ve yakıcılık özellikleri bakımından incelenmesi sonucunda, Kuzey Ege bölgesi zeytinyağlarının meyvemsiliğinin, Güney Ege bölgesi zeytinyağlarının ise yakıcılık özelliğinin yüksek değerler aldığı belirlenmiştir. Acılık değeri ise bölgesel açıdan bakıldığında, Güneydoğu Anadolu (Gaziantep) bölgesinin en yüksek değeri aldığı tespit edilmiştir. Ayrıca meyvemsiliğin Ayvalık çeşidinde, acılığın Gemlik ve Arbequina çeşidinde, yakıcılığın Ladolyas ve Ayvalık çeşidinde yüksek değerler aldığı saptanmıştır. Panelistlerin yorumlarında, Ayvalık çeşidi için “yeni kesilmiş ot, çağla, badem ve meyve kokuları” , Uslu çeşidi için, “çağla, çimen, yeşil domates”, Ladolyas çeşidi, “yeni kesilmiş ot, badem”, Memecik çeşidi için “çağla, badem, çiçeksi”, Arbequina çeşidi için erken hasatta, “yeşil ceviz, yeşil elma”, olgun hasatta, “domates, meyvemsi”, Sarıulak çeşidi için, “elma ve sebze”, Gemlik çeşidi için, “şeftali, kırmızı elma”, Haşebi çeşidi için, “çağla, badem, ıslak tahta”, Halhalı çeşidi için, “odunsu”, Nizip çeşidi için, “odunsu, kuru odun” ifadelerini kullanmıştır. Hasat durumları erken ve olgun, üretim yöntemleri iki ve üç faz santrifüj sistem olarak belirlenen natürel zeytinyağı örneklerinin, meyvemsilik, acılık ve yakıcılık özelliklerinin erken hasat ürünlerde ve iki faz santrifüj sistemlerde yüksek algılandığı ve özelliklerin hem hasat durumu hem de üretim yöntemi için yüksek değerden düşük değere doğru meyvemsilik, yakıcılık ve acılık olarak sıralandığı görülmektedir. Natürel zeytinyağı örneklerinin büyük çoğunluğu natürel sızma olarak derecelendirilirken, sadece bir adet yağ ham zeytinyağı olarak nitelendirilmiştir. Fiziksel, kimyasal özellikler ile duyusal özellikler arasında korelasyon analizi sonucunda, yakıcılık ile acılık arasında ve toplam fenol ile yakıcılık arasında pozitif yönlü güçlü bir korelasyon saptanmıştır. Ayrıca meyvemsilik ile ransid özellik arasında negatif yönlü güçlü bir korelasyona rastlanılmıştır.
Due to its distinctive properties and mechanically obtaining them in fresh and good quality, as grown fruits and by pressing, centrifugaling and filtering, olive oil is almost the only one within the vegetable oils which could be ingested without further refining. Due to high consumption of olive oil in the Mediterranean countries, the probability of getting caught to coronary heart disease, diabetes and certain types of cancer are low and hence people has changed their perspectives to olive oils. However, in order to maintain the positive effects on health, olive oil must preserve its naturalness during and after treatment. For this reason, by analyzing the factors that affect the olive oil quality; the type of oil, the region of growth, harvest and processing stages are primarily important. In order to maintain the quality, the physical, chemical and sensorial analysis and country-level characterization should be necessary. As both a producer and a consumer, our country does not have much research on this respect. Comparing with world’s olive oil production, Turkey is at the 6th place with 5% of the portion. While in our country olive trees are grown in Aegean, Marmara and Southeastern Anatolian region, a significant part of the production is made in Aegean Region and much of the production is considered to be olive oil. However, most of the olive produced in Marmara Region is for dinning. Olives are produced as oil in the Mediterranean region, where Hatay (Antakya), Icel, Adana and Antalya holds the major part. Under the influence of Mediterranean climate, the major portion of olive oil production in Gaziantep, Kilis, Sanliurfa, Kahramanmaras and Mardin are for oil. Especially in Artvin, for regions have microclimates olive is produced as dinning. In this view, our country is suitable for olive-for-oil production. As the consumption of olive oil around the world is increasing day-by-day, it has been long known that, as we examine the oil consumption per person in Turkey, it is lower comparing with the Mediterranean countries. However, it has been shown graphically that the consumption increasing as years go by. This results an increasing demand on further studies in Turkey which has a high potential in oil production and consumption. In this study, determination of physical, chemical and sensual profiles of olive oils produced in North Aegean, South Aegean, Mediterranean, Southeastern Anatolia and Izmir Peninsula and so that their regional characteristics specific to Turkish olive oils, has been aimed. In addition, regional publicity is provided by fulfilling the inadequate information on Turkish olive oil in literature and some insights would be brought for further studies and for producers. In this research, between October-December 2011, the 30 different analyzed virgin olive oils are collected from local producers which are at five different places including the North Aegean, South Aegean, Mediterranean, Southeastern Anatolia and Izmir Peninsula. These olive oils are obtained in three-phases and two-phase centrifugations. To assess the quality of virgin olive properties, free oil acidity, peroxide value phenols, specific absorption of ultraviolet light and color analysis has been carried out. For the sensory evaluation of 30 virgin olive oil samples, standard quantitative description analysis test and the International Olive Oil Council s recommended techniques has been applied. Free fatty acid, peroxide value, specific absorption values at ultraviolet light were analyzed according to communiques. Spectrophotometric method was used during the realization of analysis of total phenolic compounds and Lovibond tintometer method was used when analyzing the color values. On the sensory considering of natural olive oils, various methods such as flavor profile analysis, quantitative description analysis and free choice profile analysis are often used. However, comparing with the others, since quantitative description analysis is preferred, evaluatibility of sensory analysis are increased. Moreover, the QDA test method, which is developed as a result of upgrading the effective COI tests, for which the sensory quality of natural olive oils are evaluated, is shown to be effectively used in order to evaluate natural olive oils in view of quality. Sensory analysis has been performed by tasting four value samples in the morning and in the evening by panelists among the ages of 28-50 and who have International accreditation and then the results are shown spider web in diagrams. In addition, the sensory analysis of virgin olive oils graded according to the median values. The correlations between calculated physical, chemical and sensory analysis data were measured by Spearman s correlation. It has been identified that free fatty acidity and peroxide value do not exceed the ultraviolet absorption values during the regional assessment of the analysis of virgin olive oils. It has been found that; the total phenol content, analyzed by spectrophotometric methods, is between 50.86-1000.1, the phenol content is different at Izmir peninsula than any other regions and for L, a, and b values; L values vary between (-4) - (+69.61), a values between (-5)-(+7.84) and b values between 2-110.2, also chlorophyll-a content vary between 0,52-6,92 ppm and finally beta-carotene content vary between 0.09-0.86 ppm. Statistically, it has been found that free fatty acidity, peroxide value, total phenol and specific absorption of ultraviolet light values do not vary with the type, region of growth, harvest status and processing method (p> 0.05). In terms of processing methods, the difference between peroxide values have been found to be significant (p <0.01). Also in terms of region of growth and processing methods, a statistically significant difference has been found between the values of total phenol values (p <0.01, p <0.05). In terms of cultivated area, while the difference between the L and b values themselves has statistically been seen to be important (p<0.01), processing method has been found to be effective on a values (p<0.01). According to color measurement, it has been put forth that for chlorophyll-a and beta-carotene values; while the difference between the chlorophyll-a values are influenced by harvest condition, beta-carotene values also vary by different cultivated area (p<0.05). As a result of virgin olive oil examination in terms of features such as fruity, bitterness and pungency, it has been determined that the fruity feature of olive oils has higher values in North Aegan region, while South Aegan region olive oils have higher pungency. Based on regional aspects of bitterness values, it has been found that Southeast Anatolia (Gaziantep) region has the highest values. It has also been determined that, fruity has high values in Ayvalik type, bitterness has high values in Gemlik and Arbequina types and pungency is high in Ladolyas and Ayvalik type. According to Panelists comments the following expressions are used for different regional olive oil types; for Ayvalik type fresh-cut grass, green almond, almond and fruit fragrances , for Uslu type green almond, grass, green tomato , for Ladolyas type “fresh-cut grass, almond , for Memecik type “ green almond, almond, floral , , for ripe harvest Arbequina types “green walnuts, green apples” , for their late harvest “tomatoes, fruity”, for Sariulak type “apple and vegetables”, for Gemlik type “peach, red apple”, for Haşebi type “green almond, almond, wet wood , for Halhalı type “woody” and for Nizip type “woody, dry wood”. Harvest situations of early and ripe, two-and three-phase centrifugation system designated as production methods, samples of virgin olive oil, fruity, bitterness and pungency properties were high-detected at the two-phase centrifugation systems and early harvest products. Virgin olive oil samples are listed both harvest status and method of production from high value to low value as fruity, bitterness and pungency. While most olive oil samples are graded as natural virgin olive oils, only one has been described as lampante oil. As a result of correlation analysis between physical, chemical and sensory properties, a strong positive correlation between pungency and bitterness and total phenol and pungency has been established. On the other hand, a strong negative correlation between fruity and rancid property has been encountered. This study is one of the limited numbers of studies about physical, chemical and sensory quality of natural olive oils. It has been expected that, our study would fulfill the lack of information on Turkish olive oils and provide viewpoints to future studies on increasing commercial value and provide contribution to either as type or regionally determination of olive oils.
Due to its distinctive properties and mechanically obtaining them in fresh and good quality, as grown fruits and by pressing, centrifugaling and filtering, olive oil is almost the only one within the vegetable oils which could be ingested without further refining. Due to high consumption of olive oil in the Mediterranean countries, the probability of getting caught to coronary heart disease, diabetes and certain types of cancer are low and hence people has changed their perspectives to olive oils. However, in order to maintain the positive effects on health, olive oil must preserve its naturalness during and after treatment. For this reason, by analyzing the factors that affect the olive oil quality; the type of oil, the region of growth, harvest and processing stages are primarily important. In order to maintain the quality, the physical, chemical and sensorial analysis and country-level characterization should be necessary. As both a producer and a consumer, our country does not have much research on this respect. Comparing with world’s olive oil production, Turkey is at the 6th place with 5% of the portion. While in our country olive trees are grown in Aegean, Marmara and Southeastern Anatolian region, a significant part of the production is made in Aegean Region and much of the production is considered to be olive oil. However, most of the olive produced in Marmara Region is for dinning. Olives are produced as oil in the Mediterranean region, where Hatay (Antakya), Icel, Adana and Antalya holds the major part. Under the influence of Mediterranean climate, the major portion of olive oil production in Gaziantep, Kilis, Sanliurfa, Kahramanmaras and Mardin are for oil. Especially in Artvin, for regions have microclimates olive is produced as dinning. In this view, our country is suitable for olive-for-oil production. As the consumption of olive oil around the world is increasing day-by-day, it has been long known that, as we examine the oil consumption per person in Turkey, it is lower comparing with the Mediterranean countries. However, it has been shown graphically that the consumption increasing as years go by. This results an increasing demand on further studies in Turkey which has a high potential in oil production and consumption. In this study, determination of physical, chemical and sensual profiles of olive oils produced in North Aegean, South Aegean, Mediterranean, Southeastern Anatolia and Izmir Peninsula and so that their regional characteristics specific to Turkish olive oils, has been aimed. In addition, regional publicity is provided by fulfilling the inadequate information on Turkish olive oil in literature and some insights would be brought for further studies and for producers. In this research, between October-December 2011, the 30 different analyzed virgin olive oils are collected from local producers which are at five different places including the North Aegean, South Aegean, Mediterranean, Southeastern Anatolia and Izmir Peninsula. These olive oils are obtained in three-phases and two-phase centrifugations. To assess the quality of virgin olive properties, free oil acidity, peroxide value phenols, specific absorption of ultraviolet light and color analysis has been carried out. For the sensory evaluation of 30 virgin olive oil samples, standard quantitative description analysis test and the International Olive Oil Council s recommended techniques has been applied. Free fatty acid, peroxide value, specific absorption values at ultraviolet light were analyzed according to communiques. Spectrophotometric method was used during the realization of analysis of total phenolic compounds and Lovibond tintometer method was used when analyzing the color values. On the sensory considering of natural olive oils, various methods such as flavor profile analysis, quantitative description analysis and free choice profile analysis are often used. However, comparing with the others, since quantitative description analysis is preferred, evaluatibility of sensory analysis are increased. Moreover, the QDA test method, which is developed as a result of upgrading the effective COI tests, for which the sensory quality of natural olive oils are evaluated, is shown to be effectively used in order to evaluate natural olive oils in view of quality. Sensory analysis has been performed by tasting four value samples in the morning and in the evening by panelists among the ages of 28-50 and who have International accreditation and then the results are shown spider web in diagrams. In addition, the sensory analysis of virgin olive oils graded according to the median values. The correlations between calculated physical, chemical and sensory analysis data were measured by Spearman s correlation. It has been identified that free fatty acidity and peroxide value do not exceed the ultraviolet absorption values during the regional assessment of the analysis of virgin olive oils. It has been found that; the total phenol content, analyzed by spectrophotometric methods, is between 50.86-1000.1, the phenol content is different at Izmir peninsula than any other regions and for L, a, and b values; L values vary between (-4) - (+69.61), a values between (-5)-(+7.84) and b values between 2-110.2, also chlorophyll-a content vary between 0,52-6,92 ppm and finally beta-carotene content vary between 0.09-0.86 ppm. Statistically, it has been found that free fatty acidity, peroxide value, total phenol and specific absorption of ultraviolet light values do not vary with the type, region of growth, harvest status and processing method (p> 0.05). In terms of processing methods, the difference between peroxide values have been found to be significant (p <0.01). Also in terms of region of growth and processing methods, a statistically significant difference has been found between the values of total phenol values (p <0.01, p <0.05). In terms of cultivated area, while the difference between the L and b values themselves has statistically been seen to be important (p<0.01), processing method has been found to be effective on a values (p<0.01). According to color measurement, it has been put forth that for chlorophyll-a and beta-carotene values; while the difference between the chlorophyll-a values are influenced by harvest condition, beta-carotene values also vary by different cultivated area (p<0.05). As a result of virgin olive oil examination in terms of features such as fruity, bitterness and pungency, it has been determined that the fruity feature of olive oils has higher values in North Aegan region, while South Aegan region olive oils have higher pungency. Based on regional aspects of bitterness values, it has been found that Southeast Anatolia (Gaziantep) region has the highest values. It has also been determined that, fruity has high values in Ayvalik type, bitterness has high values in Gemlik and Arbequina types and pungency is high in Ladolyas and Ayvalik type. According to Panelists comments the following expressions are used for different regional olive oil types; for Ayvalik type fresh-cut grass, green almond, almond and fruit fragrances , for Uslu type green almond, grass, green tomato , for Ladolyas type “fresh-cut grass, almond , for Memecik type “ green almond, almond, floral , , for ripe harvest Arbequina types “green walnuts, green apples” , for their late harvest “tomatoes, fruity”, for Sariulak type “apple and vegetables”, for Gemlik type “peach, red apple”, for Haşebi type “green almond, almond, wet wood , for Halhalı type “woody” and for Nizip type “woody, dry wood”. Harvest situations of early and ripe, two-and three-phase centrifugation system designated as production methods, samples of virgin olive oil, fruity, bitterness and pungency properties were high-detected at the two-phase centrifugation systems and early harvest products. Virgin olive oil samples are listed both harvest status and method of production from high value to low value as fruity, bitterness and pungency. While most olive oil samples are graded as natural virgin olive oils, only one has been described as lampante oil. As a result of correlation analysis between physical, chemical and sensory properties, a strong positive correlation between pungency and bitterness and total phenol and pungency has been established. On the other hand, a strong negative correlation between fruity and rancid property has been encountered. This study is one of the limited numbers of studies about physical, chemical and sensory quality of natural olive oils. It has been expected that, our study would fulfill the lack of information on Turkish olive oils and provide viewpoints to future studies on increasing commercial value and provide contribution to either as type or regionally determination of olive oils.
Açıklama
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2013
Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2013
Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2013
Anahtar kelimeler
naturel zeytinyağı,
duyusal,
kalite,
virgin olive oil,
sensory,
quality