Yerli kiraz ve kayısının modifiye atmosferde ambalajlanması
Modified atmosphere packaging of sweet cherries and apricot
Yazar: EMEL DAMARLI
Danışman: PROF. DR. NURSEN İPEKOĞLU
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü
Derece: Doktora, 1995
Konu: Kimya Mühendisliği = Chemical Engineering
Dizin: Ambalajlama = Packaging ; Kayısı = Apricot ; Kiraz = Cherry ; Modifiye atmosfer ambalajlama = Modified atmosphere packaging

Özet:
Bu çalışmanın amacı, ülkemizde ekonomik önemi olan ürünlerimizden Napolyon çeşidi kiraz ve Hasanbey çeşidi kayısının dayanma sürelerine etkili olan ambalaj malzemesi ve modifîye atmosfer koşullarının belirlenmesidir. Çalışma kapsammda kiraz örnekleri 30,50,70 \ım kalınlıklarmdaki düşük yoğunluklu polietilenden (LDPE) üretilmiş ambalaj malzemelerinde pasif ve 50 jun kalınlığındaki LDPE ambalaj malzemesi kullanılarak %1 O2+%10 C02; %1 02+%15 C02; %1 O2+%20 C02; %3 O2+%10 C02; %3 02+%15 C02; %3 O2+%20 C02 gaz bileşimleri altmda aktif modifikasyon yöntemleri ile ambalajlanarak, kayısı örnekleri ise 50 \ım LDPE ambalaj malzemesinde pasif ve aynı malzemede %3 02+%3 C02 gaz bileşimi altmda aktif modifikasyonda ambalajlama yöntemleri uygulanarak 0°C'de 6 hafta depolanmışlardır. Kiraz ve kayısıların bir kısmı ise kontrol örnek olarak ambalajsız depolanmıştır. Modifiye atmosferde ambalajlanan örneklerin pazarlanabilme sürelerini belirlemek amacıyla depolamanm belirli sürelerinde depo ortamından alman örnekler 20°C'de 1 ve 2 gün bekletilmiştir. Örneklerin 0°C'de depolama ve 20°Cde bekletme sürelerinde, kalite değerleri değişimlerini belirlemek amacıyla kurumadde, pH, toplam asitlik, toplam çözünen katı madde, renk (Hunter L,a,b), tekstür ve duyusal değerlendirme analizleri yapılmış ve depolama süresince ambalaj ortamı gaz bileşimi değişimleri ve ağırlık kayıpları belirlenmiştir. Kiraz ve kayısmm kontrol örnek olarak ambalajsız, ve pasif ve aktif modifikasyon yöntemleri ile ambalajlanarak 0°C'de depolanmalarında; kontrol örneklerin dayanma süreleri 4 hafta, modifiye atmosferde ambalajlananlannki ise 6 hafta olarak belirlenmiştir. Kirazın pasif yöntemle ambalajlanmasında 50 \ım kalınlığında LDPE ambalaj malzemesi kullanımının, aktif yöntemde ise aynı ambalaj malzemesinde %3 O2+%20 C02 gaz bileşimi uygulamasının, 6 hafta süreyle genel kalite korunumunda etkili oldukları ve örneklerin bu sürenin sonunda 20°Cde 2 gün bekletilmelerinde, pazarlanabilme kalitelerini diğer uygulamalara göre daha fazla korudukları saptanmıştır. 50 \ım LDPE ambalaj malzemesinde pasif yöntemle ambalajlanan kayısıların, 6 hafta süreyle genel kalite korunumlannın, aktif yöntemle ambalajlananlara göre daha üstün olduğu ve bu örneklerin depolamanm 4. haftasında 20°C'de 2 gün pazarlama kalitelerini de aktif yöntemle ambalajlananlara göre daha fazla korudukları belirlenmiştir.

Abstract:
In the world today, there is an increasing tendency to consume fruit and vegetables in their fresh state. Following their harvest, fruits and vegetables are prone to spoilage as a result of respiration, biochemical changes and microbiological activity, all of these factors depending on ambient conditions. Turkey is a country with a high potential for production of fruits and vegetables. The annual increase in the production of these food commodities is about 10%. In 1990, the production of fruits reached 9 million tons and that of vegetables 22.6 million tons. However, our country cannot, as yet, utilize this production efficiently. Only 4% of the fruits and 1% of the vegetables can be exported as fresh. This avails only 233 million dollars of income, whereas experts on the subjects believe that the income from exporting of fresh fruits and vegetables can be increased to 1 billion dollars. It is estimated that 30% harvested perishable product is lost within the production-consumption chain, which costs the country 850 million dollars per year. Thus, in the fourth Five- Year Development Plan, preservation and exportation of fruits and vegetables is considered as an issue of primary importance that needs immediate support. Refrigeration and the use of low temperature is the fundamental technique used to retard deterioration and maintain fruit and vegetables in their freshest condition for as long as required after harvest. However, in some cases, low temperature alone may be insufficient to retard the ripening of fresh produce or prevent deteriorative changes which can occur during storage or even during the normal timescale required for transportation, distribution, and marketing. The favorable effects of chilled temperatures in food preservation can be improved by additional xxiiitreatments. In order to decreases losses incurred in fruits and vegetables within the production-consumption chain as well as to increase export figures, application of modern packaging technology is essential. In the last ten years, modified atmosphere packaging (MAP) of fruits and vegetables have become increasingly more important in this respect. With the application of MAP, the shelf-life of fruits and vegetables can be extended by 50-70%, an important improvement that renders the fresh food commodities the necessary protection of quality and increases its period marketability. However this technology, that find a wide area of application in developed countries, should be established in each country individually with respect to MAP parameters as fruits and vegetables cultivated under different ecological conditions respond differently to the MAP technique. Thus it is necessary to conduct research to assess the suitable conditions for the proper application of MAP technology in Turkey. The change in the normal composition of air (78,08% nitrogen, 20,96% oxygen, 0,04% carbon dioxide, variable amounts of water vapour and traces of inert gases) in contact with foods, resulting in a modified atmosphere, is one of the most effective methods of extending quality shelf-life of food commodities. However, the succesful use of modified atmosphere should be accompanied by chilled temperature storage to achieve maximum benefits. The intention behind MAP system is to minimize the respiration rate, inhibit the enzymatic and oxidative decomposition reactions, and/or delay microbiological spoilage by changing the composition of the atmosphere surrounding the produce. The conditions provided and maintained within the MAP are influenced by both the type of product and its environment. The parametres effective in MAP technique are the organoleptic and microbiological quality of raw material; optimum temperature and relative humidity; gas mixture within the packaging; resistance against oxygen, carbon dioxide and ethylene diffision; ethylene production and sensitivity; respiration rate; packaging material; microbial safety and shelf-life of product; food distribution system; light and consumer handling between sale and consumption. The appropriate use and adjusment of these parameters in the MAP system improves the durability of the product and contributes considerably to quality retention. Therefore, this system can be regarded as an optimization process. XXIVThe quality of raw materials (both organoleptic and microbiological quality) coupled with proper temperature and relative humidity througout the food change are the most important factors. A high quality product can only enhance the quality and marketability of any given finished products. Metabolic process, including respiration and ripening rate are sensitive to temperature. Biological reactions generally increase two-to-three fold every 10°C rise in temperature. Generally, fruit and vegetables will last longer at low temperatures. However every commodity has a minimum temperature limit below which chilling damage can occur with increasing respiration rate, hastening senescence and lowering the value of the commodity. One of the benefits of MAP and packaging in general is the maintenance of adequate reletive humidity within the package. There is a danger that the relative humidity can get too high, causing moisture condensation and conditions favorable for microbial growth, resulting in decay of the commodity. One of the primary effects of MAP is a lower rate of respiration, which reduces the rate of substrate depletion, C02 production, 02 consumption and release of heat. The aim of shelf-life extension is to decrease the respiration rate, so that product quality can be preserved for a certain period. The respiration rate of the product changes according to the ambient temperature; gas composition; moisture content of tissue; cultivar; state of development and postharvest handling conditions. Oxygen, carbon dioxide and ethylene are most important in influencing respiration. In general, substantial decreases in the respiration rate for most stored products do not occur until the external oxygen concentration is reduced below 10%. The optimum external concentration for a number of products held in cold storage is the 1% to 3% range. Elevation of the ambient concentration of carbon dioxide in a number of postharvest tissues impedes the forward movement of the respiratory pathway, resulting in a net and often quite significant decrease in respiration. A very important point on the handling of fresh fruit and vegetables is to take care not to damage the product both before and during their harvest and also afterwards during packaging and marketing. When the fruit and vegetables are injured and bruised, both the respiration rate and microbiological activities are increased leading to further spoilage. There are six main characteristics to consider when selecting packaging material for MA packed foods. These are resistance of puncture; sealing reliabilty; antifog properties; carbon dioxide permeability; oxygen permeability; and water vapor transmission rate. The most important feature of packaging film properties, when considering materials for MA XXVpacked foods is the gas permeability, more specifically the permeability to 02 and C02 gases. Many packaging materials with favorable gas permeability characteristics have a rather low permeability for water vapor. This may be complicating factor, because in most instances, the relative humidity in a package is very high (above 95%). Any small fluctation in the storage temperature may result in condensation. In the package, relative humidity may be controlled by using packaging materials with higher water vapor permeabilities by including sachets with water absorbers like CaCl2, sorbitol or by using packaging material with a special antifog layer which breaks the surface tension of water droplets and causes the moisture to spread from top web into sides of the package. The methods used to avail the right conditions for MA can be studied under two headings namely passive and active modification. In the passive modification, the rate of change and the composition of the modified atmosphere will depend largely on the packaged product and the permeability of the packaging material. The permeability of the packaging material to be selected should be as such that it can provide a balance between the 02 consumed by the product and the 02 passing through the packaging material. Likewise, a balance should also be established between the C02 produced by the product and the C02 penetrating through the packaging material. Only then, the desired atmospheric composition can be made available inside the packaging. The widespread method of active modification applications is the flushing of the right gas mixture into the medium after the application of vacuum. In these application, air is flushed out and replaced with the appropriate gas mixture. The aim of the work undertaken in this study was to determine the effect of different modified atmosphere conditions and packaging materials on the shelf-life and marketing period of sweet cherries (Prunus Avium L. cv. Napofyon) and apricot (Prunus Armeniaca L. cv. Hasaribey). The sweet cherries and apricots were obtained from a farm in İzmir and Malatya, respectively. After their harvest, samples were transported to laboratories within 10 hours. After sorting out of damaged fruits, the sound samples were hydrocooling. The sweet cherries and apricots were than packaged by applying the passive and active modification modes. Some of them were stored unpackaged as a control to compare the modified atmosphere systems. In the passive modification mode; the sweet cherries were sealed with 30, 50, 70fxm LDPE films and apricot was sealed with 50 [xm LDPE xxvifilm. In the active modification mode; using a Kramer Grabe vacuum and a Multivac gas mixture machine, sweet cherries were packaged under the 1% O2+10% C02; 1% 02+15% C02; 1% O2+20% C02; 3% O2+10% C02; 3% 02+15% C02; 3% O2+20% C02 gas mixtures and apricot was packaged under the 3% 02+3% C02 gas mixture. The samples were then placed into a storage room and maintained at 0°C and 90±2% relative humidity. Gas composition analyses of the internal atmosphere were carried out on triplicate samples every day during the first week and then once every week throughout the storage period. Oxygen and carbon dioxide gas analyses were carried out using the Servomex 02 analyzer model 574, and C02 analzer IR model PA 404 Triplicate readings were avaraged and recorded as one value for 02 and one value for C02. The quality parameters studied were weight losses, dry matter content (AOAC 921.151), pH (AOAQ981.12) total acidity ( AOAC, 942.15), total soluble solids (AOAC 932.12), color (Hunter Lab) and texture (Universal Instron 1140 ). Sensory evaluations were also carried out by untrained panellists to evaluate fruit quality characteristics of general appearance, color, texture, flavour and interior quality according to the hedonic scale. All panel data were then averaged for each chracteristics. Analyses were carried out at the start and in the 1st, 2nd, 3rd, 4th, 5th, and 6th weeks of cold storage. To determine the marketing qualities and periods of these samples; sweet cherry samples were transferred to the ambient conditions (20°C) for 1 and 2 days at the end of 3rd, 4th, 5th and 6th weeks of storage period and samples of apricot were transferred same conditions at the end of 3rd and 4th weeks of storage period. Same quality analyses were carried out of these samples during the holding days at the ambient conditions. The shelf-life of unpackaged control sweet cherries stored at for 4 weeks was found to be comparable shorter (50%) than those of sweet cherries under modified atmosphere conditions. In the passive modification modes, a 50\ım LDPE film was found to be more effective on the quality retention of the sweet cherries during 6 weeks of storage at 0°C and also at 20°C for 2 days at the end of this storage period, than the 30|xm and 70fxm LDPE films used. In the active modification modes, when a 50\im LDPE film was used as the packaging material, among the 6 different gas mixtures tried inside the film, the gas mixture system with 3% 02+ 20% C02 was found to be suitable to protect the overall quality of sweet cherries during the 6 weeks of storage at 0°C and also at 20°C for 2 days at the end of this storage period. The shelf-life of unpackaged apricot stored at 0°C was found 4 weeks. Applications of passive and active modes on the packaging of apricot, xxviipassive modification using 50\ım LDPE film was found to be suitable to protect the quality of apricot during 6 weeks of storage at 0°C, and also at 20°C for two days at the end of 4th weeks of the storage period. By applying the modified atmosphere packaging technology on the apricot, the shelf-life has been extended about 50%.