Soğukta saklama sırasındada manyetik alan uygulamasının dilim salam üzerinde etkilerinin incelenmesi
Effects of magnetic field treatment on quality attributes of salami during cold storage
Yazar: DÖNAY UYSAL
Danışman: DOÇ. NEŞE ŞAHİN YEŞİLÇUBUK
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Gıda Mühendisliği Ana Bilim Dalı
Derece: Yüksek Lisans, 2015
Konu: Gıda Mühendisliği = Food Engineering
Dizin: Manyetik alanlar = Magnetic fields ; Salam = Salami ; Soğuk depolama = Cold storage

Özet:
Soğukta saklama gıdaların tazeliğini ve duyusal özelliklerini korumak için kullanılan en yaygın yöntemlerden birisidir. Et ve et ürünlerini de kapsayan "taze gıda"ların muhafazası sırasında ürün güvenliği ve uzun raf ömrü sağlamak için soğukta muhafaza yöntemi çok eskiye dayanmaktadır. Son yıllarda önem kazanan, özellikle soğukta saklanan taze gıdalar için tasarlanan özel bölmelerde ozon gazı, UV-C ışık ve manyetik alan gibi yeni teknoloji uygulamaları ürünlerin daha uzun süre muhafaza edilmesine olanak tanımaktadır. Manyetik alan gıda sanayinde çeşitli uygulama alanına sahiptir. Pastörizasyon amaçlı kullanıldığında mikroorganizma sayısında önemli miktarda azalmalar sağlanabilmektedir. Meyve ve sebzelerde enzimatik aktiviteyi azaltmakta, vitamin içeriğinin korunmasına yardımcı olmakta, görünümü olumlu yönde etkilemekte ve raf ömrünü artırmaktadır.
Bu çalışmanın amacı, dilim salamın soğukta muhafazası sırasında manyetik alan  uygulamasının ürün güvenliği ve kalitesi üzerindeki etkilerinin araştırılmasıdır. Bu çalışma kapsamında tombul macar salam numuneleri yerel marketlerden TAT A.Ş. tarafından ambalajlı olarak temin edilmiş, laboratuvarda eşit kalınlıkta  dilimlenmiştir. Dilimlenmiş salam örnekleri 0 °C'yeyerleştirilmiş ve manyetik alan şiddetleri 0.1 mT, 1.0 mT, 2.0 mT olan prototip haznelerde raf ömrü boyunca depolanmıştır. Depolama süresince 0., 2., 4., 6., ve 8., günlerde ürünlerde kimyasal analizlerden pH ve TBA tayini, fiziksel analizlerden renk tayini, mikrobiyolojik analizlerden maya ve küf analizleri ve duyusal analizler yapılarak farklı manyetik alan şiddetlerinin ürünlerin saklama ömrü ve kalitesine etkisi incelenmiştir. Sonuçlar istatistiksel analiz yapılarak değerlendirilmiş ve daha önce yapılan çalışmalarla karşılaştırılmıştır.
Sonuçlar değerlendirildiğinde, 2.0 mT manyetik alan şiddetinin salam örneklerinde küf ve maya gelişimini kontrol grubu ve diğer manyetik alan şiddetlerine göre geciktirerek depolama ömrünü artırıcı etkiye sahip olduğu görülmüştür. Salam örneklerinde pH ve TBA analizleri değerlendirildiğinde 8 gün süreyle depolanan örneklerde manyetik alan şiddeti arttıkça pH değerinin arttığı, TBA değerinin ise başlangıç gününe göre önce arttığı fakat bazı günlerde TBA değerinde azalmalar olduğu gözlenmiştir. Ayrıca salamın kırmızı rengininin korunmasında 2 mT manyetik alan şiddetine sahip bölmenin daha iyi olduğu görülmüştür. Panelistler ile uygulananduyusal analiz sonuçları da manyetik alan şiddetinin yüzey yapışkanlığını geciktirmede etkili olmuştur.

Abstract:
It is a well-known fact that manufacturing milk and dairy products, meat and meat products, under non-hygienic conditions can cause serious problems for human health. As a result of various chemical and enzymatic reactions and microbial growth, products may become non-consumable. Among these, microbial growth affects the product shelf-life and food safety the worst whereas the most influential factor on the development of microorganisms is the storage temperature. For this reason, cold-storage has a great importance especially for the preservation of the so-called "fresh food" groups, sales and domestic consumption stages in terms of product safety and long shelf-life. 
Nowadays the challenges customers are facing are mainly about chemical preservatives that are used for extending shelf life and obtaining food safety. With the increase in the demands of consumers in the same way as fresh foods, especially the widespread use of non-thermal inactivation technologies increased in the food industry. Designing of special compartments with the use of new technologies such as magnetic field, UV-C light, ozone, etc. for foods stored in refrigerators is becoming increasingly important for fresh food preservation. One of the new technologies developed as an alternative to heat processing applications is the magnetic field application. Magnetic field has several applications in the food industry. Significant reductions in the number of microorganisms can be achieved by magnetic field applications when used for pasteurizing foodstuffs. It reduces the enzymatic activity of fruits and vegetables as well as it helps to protect vitamin contents of foods. It has further positive impact on appearance and increases the shelf-life. 
Today, the rapid pace of work and intensity have limited the time for shopping. On the other hand, eating habits at home have changed, and there is a tendency towards eating out. In addition, an increase has been observed in the number of people living far away from shopping areas in town. Another issue is that the number of individuals living alone has increased today. In such cases, quality losses arise as the purchased products are stored in the cold storage equipments for prolonged periods, product safety may be affected, and economic losses occur as a result of disposal of inconsumable food products. Therefore, extensive studies are carried out today to design the household-type coldstorage equipments in the best way to preserve the original features of the food products and the importance of the subject is increasing daybyday. 
For the products that need to be kept cold, ideal temperature conditions (0- ° C) and ozone, UV-C light and magnetic field applications in special compartments enables the storage of products for longer periods. Designing of special compartments with appropriate qualifications for foods stored in cold storage and the use of new technologies is becoming increasingly important in the Far East market, and increasing competition in this regard for food preservation. 
The aim of the study was to investigate the effects of magnetic field on product safety and quality practices of sliced salami during cold storage. In this study, sliced salami samples were placed in special compartments having magnetic fields at 0.1 mT, 1.0 mT and 2.0 mT. During storage, chemical, physical, microbiological and sensorial analysis were performed for 8 days at 2 days intervals in order to evaluate the effects of magnetic field strength on shelf life. TAT Gıda A.Ş provided all samples without breaking the cold chain. Salamies were cut and placed in special prototype chambers with magnetic field under hygienic conditions. All chambers were stored at 0 °C during the study.
In order to determine the physicochemical evolutions, pH, thiobarbituric acid and color measurements (L*a*b*) were applied to the samples at the beginning and at the 2nd, 4th, 6th and 8th days of storage.  Yeast and mold counts were determinedfor microbiological evaluations.
Although, there is no significant increase in the pH values of each group during storage period (p>0.05), the increase in the pH values of the 2.0 mT groups were statistically significant (p<0.05). While the TBA values of the each group were increased during storage, all values decreased after the 2nd day of the storage (p<0.05).
The results of the microbiological analyses indicated that the microorganisms of the initial microflora grew and the numbers were increased during storage and it was alsomentioned that the cold storage conditions and alternative technologies are important as much as the initial microflora on the microbiological count. When the the salami samples were investigated, it was observed that alternative applications were more effective on the preservation of quality parameters of meat cuts during storage and serving in the supermarkets. 
It was observed that mold and yeast content decreased throughout the storage period.. The lowest yeast contents observed on 4th day which were found significant (p<0.05), as discussed statistically. On the other hand, the control group showed increase throughout the storage time.
Moreover, in the pieces of salami stored under 2.0 mT magnetic field, increase in shelf-life was observed compared with the control group and other samples. There was no observation on any mold and yeast as the salamis stored at magnetic fields 2nd storage day. But also there were some yeast at the control group 2nd storage day. The results of this study indicated that application of magnetic field improved the microbiological quality and extended the shelf-life of salami.
Over this time, the samples were periodically analyzed for sensorial properties as well. Considering sensory properties of salami samples, no significant differences were observed for the parameter "appearance" between the mean scores of salami groups. It was also found insignificant over storage time (p>0,05). In addition; appearance scores increased compared to the first day scores.
The scores generally declined throughout storage for overall acceptability in all salami samples. Variations in storage time were found statistically significant (p<0.05). During storage period; samples with 1.0 mT and 2.0 mT were found to be more acceptable and highly scored with respect to overall acceptability values by panelists. 
Experimental data indicated that during storage period, sliced salami kept under 2.0 mT magnetic field had longer storage period compared to control group and other magnetic field applications in 8 days. 
It is obvious that the cold storage is not enough to protect and enhance the quality of the storage period. For this reason the combination of alternative techniques should be improved. However, literature on magnetic field on various foods  is very limited, so more investigation is necessary on applications of this technique on food.