Karayemiş tozunun fiziksel özelliklerinin iyileştirilmesi
Improvement of physical properties of cherry laurel powder
Yazar: ELA ERGÜNEY
Danışman: PROF. DR. MERAL KILIÇ AKYILMAZ ; DR. FATMA EBRU FIRATLIGİL DURMUŞ
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Gıda Mühendisliği Bölümü / Gıda Mühendisliği Ana Bilim Dalı
Derece: Yüksek Lisans, 2013
Konu: Gıda Mühendisliği = Food Engineering

Özet:
Karayemiş Türkiye?nin Karadeniz Bölgesi?ne özgü, fenolik maddeler ve C vitamini bakımından zengin bir meyvedir. Aroma verici katkı olarak gıda endüstrisinde kullanılmaktadır. Özellikle Karadeniz Bölgesi?nde, taze veya kurutulmuş olarak tüketilmekte, reçel, marmelat, konserve ve turşu olarak değerlendirilmektedir. Karayemiş bazı hastalıkların tedavisinde ve kozmetik endüstrisinde de kullanılmaktadır.
Taze meyveye alternatif bir tüketim formu olarak sunulan meyve tozları, raf ömürlerinin uzun olması, her mevsimde tüketilebilmeleri, lezzetli ve doğal oluşları nedeniyle, gıda endüstrisinde özellikle ara ürün olarak yaygın bir biçimde kullanılmaktadır.
Meyvelerde bulunan şeker, toz ürünlerin üretiminde sıklıkla karşılaşılan yapışkanlık, topaklaşma ve kekleşme sorunlarını arttırıcı rol oynarlar. Karayemiş tozu da, meyvenin bileşiminden dolayı yapışkan özellik göstermektedir. Bu özelliği meyve tozu olarak üretimini ve kullanımını kısıtlamaktadır. Meyve tozlarının üretiminde bu sorunların çözülmesinde maltodekstrin ve trikalsiyum fosfat gibi katkılar kullanılmaktadır. 
Bu çalışmada, karayemiş püresine maltodekstrin DE5, maltodekstrin DE47 ve trikalsiyum fosfat eklenerek, dondurarak kurutma yöntemi ile farklı toz örnekleri hazırlanmıştır. Maltodekstrinler karayemiş püresine yaş bazda %10, trikalsiyum fosfat ise yine yaş bazda %5,36 oranında eklenmiştir. Örneklerde nem içeriği, su aktivitesi, higroskopi, kekleşme derecesi, dağılabilirlik, renk ve camsı geçiş sıcaklığı ölçülerek karşılaştırılmıştır.
Örneklerin nem içeriği %1,1-2,4 aralığında bulunmuştur. Katkı maddesi kullanımı ile örneklerin nem içeriği azalmıştır. Maltodekstrin ve trikalsiyum fosfatın kullanıldığı örnekler en düşük nem içeriğine sahip bulunmuştur. Örneklerin su aktivitesi 0,17-0,21 aralığında bulunmuştur. En düşük su aktivitesi maltodekstrin ve trikalsiyum fosfatın birlikte kullanıldığı örneklerde, en yüksek su aktivitesi ise kontrol numunesinde bulunmuştur. Meyve tozunun higroskopi ve kekleşme derecesi kullanılan katkılar ile azalmıştır. En düşük higroskopi ve kekleşme derecesi maltodekstrin ve trikalsiyum fosfatın birlikte kullanıldığı numunelerde saptanmıştır. Meyve tozunun suda dağılabilirliği kullanılan katkılar ile artmıştır. En yüksek dağılabilirlik maltodekstrin ve trikalsiyum fosfatlı numunelerde gözlenmiştir.
Renk analizi sonucunda, rengin parlaklığını temsil eden L* değeri katkı maddesi oranı arttıkça yükselmiştir. Katkı maddeleri oranı arttıkça örneklerde yeşillik-kırmızılık gösteren a* değeri artmış, mavilik-sarılığı gösteren b* değeri ise azalmıştır. Kullanılan katkı maddeleri camsı geçiş sıcaklığını yükseltmiştir.
Karayemiş tozunun üretiminde maltodekstrin ve trikalsiyum fosfatın birlikte kullanımı en iyi fiziksel özellikleri sağlamıştır. Karayemiş tozunun üretiminde maltodekstrin ve trikalsiyum fosfatın birlikte kullanımı tavsiye edilmektedir.

Abstract:
The cherry laurel is a typical fruit from the Black Sea reagion of Turkey rich in phenolic compounds and vitamin C. It is used as a flavoring additive in the food industry. It is consumed as fresh and dried, its jam, marmalade, canned and pickled forms are produced especially in Black Sea region. Cherry laurel is also used in treatment of some diseases and cosmetic industry.
Fruit powders that present an alternative form to fresh fruits are commonly preferred by the food industry especially as an ingredient for their long shelf life, use in any season, their taste and being natural. Sugars present in fruits augment stickiness, agglomeration and caking problems encountered in the production of powdered products. Cherry laurel powder also exhibit stickiness due to its composition. This limits production of its powder and use. 
Drying aid agents and anticaking agents arefrequently used to prevent these problems in fruit powders. Maltodextrin, as a drying agent and tricalcium phosphate, as an anti-caking agent are commonly added to fruit powders to obtain a nonsticky, free flowing powder. The ratio additive/fruit pulp or puree may change according to the composition of the fruit.
In this study, different powder samples are prepared by adding maltodextrin DE5, maltodextrin DE47 and tricalcium phosphate to puree of cherry laurel and  then freeze drying method. Five samples were prepared by using maltodextrin DE5, maltedextrin DE47, tricalcium phosphate, maltodextrin DE5+tricalcium phosphate and maltodextrin DE47+tricalcium phosphate. A control sample without any additive was also prepared. The amounts of maltodextrin and tricalcium phosphate used in fruit puree were 10 and 5,36%, respectively. 
Water content, water activity, hygroscopy, caking degree, dispersibility, colour and glass transition temperature of the samples were measured and compared. 
The humidity content of powders is measured using the AOAC gravimetric method. 
The water activity is defined as the vapor pressure of a liquid divided by that of pure water at the same temperature. It is determined using Protimeter device (water activity measuring device of Meter House).
Hyroscopy is the ability of food powder to absorb moisture from an environment with high relative humidity. The high content of glucose and fructose in fruit powders is responsible for strong interaction with the water, as these molecules have polar terminals. The hygroscopy is expressed as the final moisture content attained after exposing the powder in an evironment of 79.5% relative humidity.
Caking degree is expressed as the percentage of the redried (102 C, 1 h) humid powder (exposed in 79.5% relative humidity) remaining on a sieve of 495 µm. 
Dispersibility is the ability of powder to get wetted without formation of dry lumps in water. According to the dispersibility measurement method of International Dairy Federation, the powder is stirred in the water for a determined period, then poured through a 212 µm size sieve. The dry matter of the filtered water is determined using the gravimetric method.
The colour is mesured using a chromameter (Conica Minolta Chromameter CR-400) on pressed powder samples.
In many studies, concepts regarding to the water activity and to the glass transition temperature are evaluated together to understand the role of the water in the food. The glass transition temperature is the temperature where amorphous materials pass from a hard and relatively brittle state into a molten or rubber-like state. In temperatures above the Tg, crystallization occurs. As fruit powders are amorphous materials, they should be kept below their Tg. The addition of materials with high Tg is a frequently used solution to increase the Tg of powders.
The glass transition temperature is measured using a Differential Scanning Calorimeter which has as principle to determine the change on the heat capacity. Tg is accepted as the initial or the middle point of heat capacity change. Tg of foods vary between -135 °C and 250 °C. The Tg of pure water is -135°C, while a polymer with high molecular weight as starch has 250 °C as Tg.    
As results of the study, the humidity content of the samples were found between 1,1%-2,4%. The sample with maltodextrin DE5 and tricalcium had the minimum water content, while the control sample with any additive had the maximum. The water activity was between 0,17-0,21. The lowest water activity was shown by the sample with maltodextrin DE5 and tricalcium phosphate. The highest was shown by the control sample. The highest hygroscopicity was found for the control sample (9,19%), followed by the sample with only maltodextrin DE5 (5,39%). The lowest hygroscopicity is measured for the sample with maltodextrin DE5 + tricalcium phosphate (2,87%). The dispersibility in water was the lowest for the control sample (81,12%), then for maltodextrin DE5 and maltodextrin DE47 (87,25%, 87,49%). The highest dispersibility values were for maltodextrin DE5 + tricalcium phosphate (95,03%) and maltodextrin DE47 + tricalcium phophate (94,58%). The degree of caking was found 29,62% for the control sample, 23,54% for the sample with maltodextrin DE47, 23,18% for the sample with maltodextrin DE5, 18,29% for the sample with tricalcium phosphate, 16,17% for maltodextrin DE47 + tricalcium phosphate and 16,06% for maltodextrin DE5 + tricalcium phophate. The color measurement gave the values between 33,39-50,78 for L which is the lightness of the color. The lightness increased as the amount of additive in the sample increased. The a value, which is for green-red direction of the color, was found between 12,86-17,62 and decreased with increasing additive amount. The b value, which means the blue-yellow direction, was between 5,63-9,12 and decreased with increasing additive amount. 
As the conclusion of the study, it can be said that the use of maltodextrin and tricalcium phosphate together gave the best result for the improvement of physical properties of cherry laurel powder.