Determination of Color Quality and Hmf Content of Unprocessed Sultanas Obtained from Different Vineyards
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Sept. 2014. Vol. 2, No.5 ISSN 2311 -2476 International Journal of Research In Agriculture and Food Sciences © 2013 - 2014 IJRAFS & K.A.J. All rights reserved http://www.ijsk.org/ijrafs.html DETERMINATION OF COLOR QUALITY AND HMF CONTENT OF UNPROCESSED SULTANAS OBTAINED FROM DIFFERENT VINEYARDS 1RAMAZAN ŞEVİK, 2LEVENT ŞEN, 3SEBAHATTİN NAS 1Prof., Department of Food Engineering, Afyon Kocatepe University, Afyonkarahisar, Turkey 2Asstt. Prof., Department of Food Engineering, Giresun University, Giresun, Turkey 3Prof., Department of Food Engineering, Pamukkale University, Denizli, Turkey E-mail: [email protected] , [email protected] , 3 [email protected] ABSTRACT Twenty sultana type raisin samples obtained from seedless grapes grown in three different altitudes in Denizli province in Aegean region of Turkey were analyzed for some important quality parameters for the sultanas such as pH, titratable acidity (TA), color quality as L*, a*, b*, a/b*, Chroma (C), hue angle (H°) and hydroxymethylfurfural (HMF) content. The effects of altitude of the vineyards on quality parameters of sultanas were also investigated. pH of the samples ranged from 3.31 to 4.21 and TA values ranged from 0.65 to 1.75 g 100 g-1 as tartaric acid. It was found that the effect of vineyard altitudes on the mean pH and TA acidity values of the samples were not significant (P>0.05). However, color analysis indicates that mean a* values of the samples increased with decrease of mean altitude of vineyards (P<0.05) but this inclination hadn’t seen on L*, b*, a/b*, H° and HMF values (P>0.05). Keywords: Sultana, raisin, color, HMF, altitude, pH 1. INTRODUCTION In order to obtain desirable sensory or texture Grapes have been cultivated for thousands of years property or to provide microbiological safety as and were dried into raisins since at least 1000 B.C. well as to eliminate enzymatic activities, food (Parker et al., 2009). Due to the considerable high products are frequently subjected to thermal sugar and moisture content, seedless grapes are treatment such as, cooking, baking, drying, very susceptible to microbial spoilage during roasting, extrusion, pasteurization or sterilization, storage. Hence, in order to minimize economic etc. The reactions related to the thermal treatment losses, seedless grapes must be consumed or are very important for the production of sensory processed into several products within a few attributes such as flavor, taste and color (Kowalski weeks. Raisin production is one of the most applied et al., 2013). Drying fruit is an ancient practice for processing method among the grape producer the preservation of food is still in use nowadays countries (Bai et al., 2013). Viticulture is an (Coimbra et al., 2011). Dried vine fruit is a term important component of agriculture in Turkey, given to all varieties of dried grape produced and where grape production is 4.5 million tons with the process of drying fruit in the sun and which 462,302 hectare of land planted with vines commercially classified into three groups as raisins (Geyikçi, 2013). Turkey is one of the most (dried white grapes), sultanas or sultanina (dried important producers of dried seedless raisins white grapes from seedless varieties) and currants around the world with USA, Chile, China and Iran. (are grown in the same way as Raisins and Sultanas Seedless grape production of Turkey is about although they are a much smaller fruit) (Covarelli 286,570 tons as dry basis (Şen and Nas, 2013). et al., 2012). Sultana type grapes are an important grape cultivar in Aegean region of Turkey due to its adaptability The Sultanas are produced conventionally by to climate and soil and increased international dipping the grape in cold alkaline solution (usually demand. 5-7% K2CO3 and 0.5% olive oil or 2.5% K2CO3 and 2% Ethyl oleate as surfactant) and then 32 Sept. 2014. Vol. 2, No.5 ISSN 2311 -2476 International Journal of Research In Agriculture and Food Sciences © 2013 - 2014 IJRAFS & K.A.J. All rights reserved http://www.ijsk.org/ijrafs.html subjecting it to the sun or oven drying (Çolak, high content of both reducing sugars and amino 2012; Pateraki, 2008). The “cold dip” process is acids (Zhao and Hall III, 2008). The occurrence of critical procedure that complex interactions among Maillard reactions is normally detected by means the alkaline dipping- oil components and surface of measurement of decreases in free-amino acids waxes on fresh grape berries tend to changes in over time and subsequent appearance of specific physicochemical properties of surface waxes that sugar fragmentation intermediates such as 5-HMF result in faster dehydration and so less opportunity which is produced via 1,2 enolisation of glucose for initial browning reactions that accompany derived Amadori intermediates. Chemical and drying and as a result producing high quality physical factors such as pH, aw and temperature raisins (Chayjan et al., 2011; Frank et al., 2004; affect both Maillard and PPO processes (Frank et Doymaz and Pala, 2002). After cold dipping al., 2004; Nursten, 2005). process, bunches of grapes are hanging onto 2 rowed and 6-8 storey vertical wire or nylon hangers In this study, some chemical and physical quality or layered onto horizontal wire racks. Both of the parameters such as color and HMF content of the systems used for drying grapes are open- sided, sultanas are evaluated. By this way, quality sheltered drying sheds and allows cross- winds to parameters of the sultanas produced in Turkey may accelerate drying process. On the other hand, small be exposed. scale grape growers have been used concrete floors 2. MATERIALS AND METHODS with polypropylene canvas for drying their grapes in Turkey. No matter which system used for Sultana Samples drying, the grape bunches should be dried under Three districts located within the boundary of the sun until the water content at least 16-18% Denizli province, Bekilli, Buldan and Honaz were (w/w) (Akdeniz, 2011). chosen for this study since intensive grape cultivation and seedless raisin production. 20 The color is one of the most important vineyards belonging to study area were chosen. characteristic that determines consumer admiration From each vineyard, sun- dried sultanas were among the raisin quality parameters (Ozilgen et al., collected on January 2011 after 4 months of vintage 1997; Bingol et. al., 2012; Ong and Law, 2010). and drying season of the region. 10 samples from Right Margin Light golden to amber color characteristics are Bekilli, 4 samples from Honaz, and 6 samples from 1.25 preferable by both local and export markets. It is Buldan districts were collected. Altitude, Latitude thought that the enzymatic and non-enzymatic and Longitude parameters of the vineyards is reactions are responsible for color change of the demonstrated in Table 1 and Figure 1. All of the sultanas (Bahaabad and Esmaiili, 2012). During sultana samples were dried within or near the grape drying, endogenous phenolic compounds vineyards by grape producers and stored at room comes into contact with polyphenolaxidase (PPO) temperatures. For physical and chemical analysis, enzymes which initiates enzymatic browning and 3x 1000 g samples of seedless raisins were taken this reaction can occur in the presence of molecular from each vineyard and kept in plastic bags and put oxgen. Normally, PPO is separated from the main in cooled boxes (4 °C) and transferred to the grape phenolic substrate in healthy berry tissue. As laboratory within a day.Back-propagation is an a consequence of physical damage during drying iterative, gradient search, supervised algorithm due to berry shrinkage and tissue collapse by virtue which can be viewed as multiplayer non-linear of water loss, the PPO enzyme comes into contact method that can re-code its input space in the with grape phenolic substrate mainly trans-caftaric hidden layers and thereby solve hard learning acid (trans- ceffeoyl tartaric acid). Also, color problems. The network is trained using ANN formation is the primary characteristic of Maillard technique until a good agreement between predicted reaction. gain settings and actual gains is reached. Maillard reactions defines as non-enzymatic pH browning reactions are a hierarchy of phenomena 200 grams of sample was put in blender jar (Waring that start with the reaction of amino acid or protein 8011S, Torrington, CT) and homogenized at high group with glycoside hydroxyl of sugar, reducing speed for 2 minute and homogenate was used to sugars and finish by formation of nitrogen determine pH. The pH meter (WTW, pH720, USA) polymers (Bahaabad and Esmaiili, 2012; was calibrated with standart buffers 4, 7 and 10 Çağlarirmak, 2006; Frank et al., 2004; Burdurlu (Merck, Darmstad, Germany) before use and Karadeniz, 2002). Thus, the sultanas are (Mahmutoglu et al., 1990). susceptible to the Maillard reactions because of 33 Sept. 2014. Vol. 2, No.5 ISSN 2311 -2476 International Journal of Research In Agriculture and Food Sciences © 2013 - 2014 IJRAFS & K.A.J. All rights reserved http://www.ijsk.org/ijrafs.html Figure 1. Map of the denizli state, located in southern aegean region of turkey, with demonstration of the studied area Table 1. Altitude, latitude and longitude parameters of the studied vineyards. Location Altitudea Latitude Longitude BK1 861 38° 14ʹ 04’ 29° 24ʹ 36’ BK2 832 38° 13ʹ 38’ 29° 24ʹ 58’ BK3 819 38° 13ʹ 33’ 29° 25ʹ 29’ BK4 828 38° 13ʹ 14’ 29° 24ʹ 52’ BK5 864 38° 14ʹ 13’ 29° 25ʹ 37’ BK6 746 38° 16ʹ 50’ 29° 20ʹ 57’ BK7 744 38° 17ʹ 21’ 29° 21ʹ 11’ BK8 698 38° 14ʹ 29’ 29° 18ʹ 20’ BK9 703 38° 14ʹ 26’ 29° 18ʹ 11’ BK10 696 38° 14ʹ 21’ 29° 17ʹ 41’ HN1 523 37° 49ʹ 48’ 29° 24ʹ 20’ HN2 526 37° 49ʹ 28’ 29° 24ʹ 21’ HN3 537 37° 45ʹ 40’ 29° 17ʹ 18’ HN4 551 37° 44ʹ 59’ 29° 18ʹ 27’ BL1 257 38° 02ʹ 55’ 28° 55ʹ 14’ BL2 250 38° 02ʹ 41’ 28° 55ʹ 20’ BL3 737 38° 07ʹ 47’ 28° 54ʹ 39’ BL4 723 38° 07ʹ 53’ 28° 53ʹ 56’ BL5 235 38° 02ʹ 40’ 28° 55ʹ 39’ BL6 208 38° 02ʹ 23’ 28° 56ʹ 11’ aMeters above sea level 34 Sept.