Farklı bariyer özelliklerine sahip ambalaj malzemelerinin bazı toz gıdaların kalitesi ve raf ömrüne etkileri
Effects of packaging materials with different barrier properties on the quality and shelf life of some powdered foods
Yazar: FERİDE SONVERDİ
Danışman: PROF. DR. GÜRBÜZ GÜNEŞ
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Gıda Mühendisliği Ana Bilim Dalı / Gıda Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2023
Konu: Gıda Mühendisliği = Food Engineering
Dizin: Ambalaj materyalleri = Packaging materials ; Gıda endüstrisi = Food industry ; Gıda kalitesi = Food quality ; Raf ömrü = Shelf life

Özet:
Toz gıdalar, katı maddelerin kırılması, öğütülmesi veya sıvı maddelerin dehidrasyonu ve kristalizasyon gibi yöntemler sonucu oluşmuş ince ve küçük partiküllere sahip kuru maddelerdir. Gıda endüstrisinde toz gıdalar çeşitli kaynaklardan, çeşitli yöntemlerle elde edilebilmesi sonucunda geniş bir kullanım alanına sahip olup son ürün, ara ürün veya gıda bileşeni olarak kullanılabilmektedir. Toz gıdaların düşük su aktivitesi nedeniyle mikrobiyal bozulmalara karşı dayanıklı olduğu bilinmekle birlikte, kimyasal bozulmalar için sıcaklık, nem, hava ve ışık faktörleri, raf ömrü ve ürün kalitesini etkileyen en önemli dış etkenlerdir. Dolayısıyla dış etkenlere maruziyeti azaltarak toz ürün kalitesini korumak ve maliyeti azaltmak için uygun bir ambalaj materyali seçimi önem kazanmaktadır. Bu nedenle bu çalışmada, farklı gaz geçirgenliklerine sahip üç çeşit ambalaj materyalinin, ticari olarak üretilmiş toz haldeki kıtırlı domates çorbası, çıtır pane harcı ve köfte harcı örneklerinin kalite özelliklerindeki etkisini incelenmek amaçlanmıştır.
Belirlenen ürünler ticari bir işleme hattında üretilmiş ve ambalajlara dolumu yapılmıştır. Kullanılan ambalajlar Ambalaj-1, Ambalaj-2 ve Ambalaj-3 olarak isimlendirilmiş olup çok katmanlı polimer materyallerden oluşmaktadırlar. Yüksek bariyer özelliğine sahip ambalajların gaz geçirgenlik hızları sırasıyla 1,31, 17,07 ve 4,79 cm3/m2.gün olup birbirlerinden önemli derecede farklı bulunmuşlardır. Su buharı geçirgenlikleri ise sırasıyla 2,29, 1,45, ve 1,81g/m2.gün olup önemli bir fark tespit edilmemiştir. Hazırlanan örnekler; -15°C (kontrol örnekleri için) ve oda sıcaklığında (25°C) 12 ay boyunca ve 35°C'de (hızlandırılmış koşullar) 10 ay boyunca olmak üzere üç sıcaklık koşulunda depolanmıştır. Her iki ayda bir raf ömrü analizleri olarak ambalaj tepe boşluğu gazı ölçümü, görsel değerlendirme, nem, su aktivitesi, renk, oksidasyon ve duyusal analizler yapılmıştır. 
Tüm ürünler için Ambalaj-1 ve Ambalaj-3 tepe boşluğu O2 miktarları azalmış ve CO2 miktarı artmıştır. Gaz içeriğindeki değişimler tüm Ambalaj-2 kodlu örneklerde ve tüm çıtır pane harcı örneklerinde daha az gözlenmiştir. Depolama sıcaklığı ve süresi kıtırlı domates çorbası renginde azalmaya sebep olmuşken, renkte ambalaj materyaline bağlı bir değişim gözlenmemiştir. Çıtır pane harcı ve köfte harcı örneklerinin rengini ise hiçbir parametre etkilemeyip, değişiklik gözlenmemiştir. Ambalaj materyalinden bağımsız olarak, her örnek için farklı oranda olmak üzere, nem miktarları azalmış ve oksidasyon analizi için ölçülen tiyabarbitürik asit ile reaksiyona giren madde (TBARS) miktarları artmıştır. Ancak TBARS değeri kıtırlı domates çorbasında yüksek oranda artmışken, çıtırlı pane harcında çok az bir atış gözlenmiştir. Duyusal analizlerde kıtırlı domates çorbasındaki renk değişimi açıkça görülmüştür. Ancak diğer örnekler için duyusal kalitede, renk, koku, tat ve genel kabul edilebilirlik özelliklerinde herhangi bir değişiklik gözlenmemiştir. Sonuç olarak O2 geçirgenlik hızları 1,31-17,07 cm3/m2.gün değerlerinde olan ambalaj materyallerinin 12 aylık depolama süresi boyunca toz gıda örneklerinin kalitesine önemli bir etkisi bulunmamıştır.

Abstract:
Powdered foods are dry substances with fine and small particles which can be obtained by methods such as crushing and grinding of solids, dehydration of liquid substances or crystallization. In food industry, powdered foods have a wide range of use such as final product, ingredient or food component, as a result of being obtained from various sources and methods. The rapid and complete dissolution of powdered foods is an important quality criteria for consumers. The composition, functional and structural properties of these products vary due to the diversity of their chemical and physical structure. Although it is known that powdered foods are resistant to microbial spoilage due to low water activity, the increased surface area allows food to contact with environment. External factors as temperature, humidity, oxygen and light are the most important factors leading to chemical deteriorations that effect the shelf life and quality of the product. 
Therefore, the selection of a suitable packaging material gains an importance in order to reduce the exposure to environmental factors so that quality of powdered foods will be preserved while economical value of packaging process can be adjusted. In order to ensure overall acceptability of powdered foods throughout the storage period, packaging materials which protect the product from moisture changes, color degradation, off-odor and off-flavor, are being used. Although the packaging material consists of metal, paper and polymer; since polymer materials are flexible, they ensure less material use and take up less space. The stability of product during storage relies on gas and water vapor permeability of packaging material and packaging method. Therefore, this study investigated the changes in different quality parameters of commercial'Kıtırlı Domates Çorbası' (an instant tomato soup with crispy bread pieces), 'Çıtır Pane Harcı' (a crispy powdered blend for coating chicken meat), and 'Köfte Harcı' (a powdered mixed flavors for making meatball) samples in powdered form, packaged with three different materials having different gas permeabilities. 
The commercial food products were were packaged with different multilayered polymer materials, having high barrier properties,  named 'Ambalaj-1', 'Ambalaj-2' and 'Ambalaj-3'in a commercial food plant. O2 transmission rate (OTR) of materials were found significantly different from each other at 1.31, 17.07, and 4.79 cm3/m2.day respectively. Water vapor transmission rates (WVTR) of the packages were determined as 2.29, 1.45, and 1.81g/m2.day respectively with no significant difference. The samples were kept in three storage temperatures: -15°C (as control) and room temperature (25°C) for 12 months and 35°C (accelerated conditions) for 10 months. 
At beginning of the study, moisture, protein, total ash, total fat and total carbohydrate contents were examined for each product. The total fat content was found to be the highest in 'Kıtırlı Domates Çorbası' samples and total carbohydrate content was the highest in 'Çıtır Pane Harcı' samples due to its high flour content. Total ash content was similar in 'Kıtırlı Domates Çorbası' and 'Köfte Harcı' samples while 'Çıtır Pane Harcı' samples have lower levels.
 Every 2 months, quality analyses were done by headspace gas composition of the packages, clumping, color, moisture, water activity, oxidation by thiobarbituric acid reactive substances (TBARS), and sensory analyses. TBARS analysis were performed with spectrophotometric measurement using calibration curve indicating Malondialdehyde (MDA) content. In sensorial analysis, 8 panelist were selected by screening test and trained. Throughout the study, descriptive analysis were done to examine the changes in odor, color, flavor and overall acceptability. The off-odor, off-flavor, rancid flavor and after taste were observed according to their presence in products.
The results were evaluated with statistical analysis by performing General Linear model and one-way ANOVA analysis to examine the differences between packaging, temperature and time parameters. If a difference between groups was noticed, Tukey test was applied to determine which groups are different from each other.
The OTR of packages affected the head space gas composition of packages. For each food product, 'Ambalaj-1' and 'Ambalaj-3' headspace O2 contents decreased while CO2 increased. The highest decrease in O2 was observed in 'Ambalaj-1' packages which have the lowest OTR while he changes in the gas composition occurred less in all 'Çıtır Pane Harcı' packages and, all 'Ambalaj-2' samples having highest OTR from other samples.
Changes in color of samples during the storage period were examined by visual evaluation, colormeter and sensory analysis. Storage temperature and time resulted in color degradation in 'Kıtırlı Domates Çorbası', yet the packaging material had no impact. The color degradation in 'Kıtırlı Domates Çorbası' were clearly noticed during sensorial analyses as well. However, any other changes in sensorial quality in the means of color, odour, taste, and overall acceptability were not observed in other samples.  There were no significant color changes observed in other samples according to packaging material, storage conditions and time.
Regardless of the packaging material, the moisture content decreased and TBARS value increased due to high storage temperature and time. TBARS values of 'Kıtırlı Domates Çorbası' (from 16,20 µmol/g to 35,30 µmol/g), 'Çıtır Pane Harcı' (from 0,07 µmol/g to 0,89 µmol/g) and 'Köfte Harcı' (from 2,37 µmol/g to 6,80 µmol/g) were increased in different rates. This could be caused from the product composition, since 'Çıtır Pane Harcı' samples with the lowest fat content and ingredient diversity, has the lowest TBARS value. Moreover the higher amount of TBARS in 'Kıtırlı Domates Çorbası' is thought to be due to the high content of lycopene showing pro-oxidant properties. Although the differences between the packages are low, it was noticed that the TBARS value in the 'Kıtırlı Domates Çorbası' samples, where the highest increase was observed, was higher in the samples in the 'Ambalaj-2'. This can be explained by the fact that samples were exposed to more O2 since its amount in headspace gas composition was not decreased as much as other packages and resulted in acceleration of oxidation reactions. However, the amount of oxidation in the samples could not be clearly detected as an oxidized, rancid taste by the panelists during the sensory analysis for the samples stored at room conditions. The panelists only detect rancid and off-flavors in samples stored at accelerated conditions regardless from packaging material. Therefore, it can be said that a significant level of oxidation did not occur in the samples within 12 months at room conditions, and the oxidation level measured by the TBARS method was below the sensory detection limit. 
As a result of the sensory analysis, no significant changes were observed in powdered foods depending on the packaging materials. For accelerated shelf life analysis, different degrees of variations were observed in the quality characteristics of the samples stored at 35°C. Although significant reductions were detected after 10 months of storage for some criteria, none of the samples reached an unacceptable level.
In conclusion, the packaging materials with OTR in the range of 1.31-17.07 cm3/m2.day did not affect quality of the food products significantly during the 12-month storage. Therefore, in order to make a selection between packaging materials with gas permeabilities in those range, factors such as packaging cost, environmental effects of packaging such as biodegradation rate and material durability can be taken into account.