Determination of the effect of modified atmosphere packaging process on quality characteristics of locally consumed Pleurotus eryngii var. formulae and allium Tuncelianum

Recently, the desire to consume healthy food and to reach these foods easily has been increasing. Minimally processed foods are at the forefront of the healthy and nutritious food group. Modified atmosphere packaging is a food preservation method used to extend the shelf life of minimally processed foods and ensure food safety. This study was conducted to investigate the feasibility of modified atmospheric packaging in order to preserve the food quality and food safety of kunkor mushroom and Tunceli garlic under refrigerator conditions. In this thesis, samples of kunkor mushroom (Pleurotus eryngii var. ferulae) belonging to the Pleurotus family and Tunceli garlic (Allium tuncelianum) belonging to the Alliaceae family obtained from the Tunceli-Ovacık region in 2019 were used. Modified atmosphere packaging (MAP) was applied to the samples used in the study with gas mixtures containing 5% O2 - 5% CO2, 3% O2 - 8% CO2 and 3% O2 - 5% CO2. The samples under the MAP conditions and unpackaged samples used as control were stored at 4 ˚C for 12 days and 12 weeks for mushroom and garlic samples, respectively. Storage-related quality changes in mushroom and garlic samples were investigated. During the storage, weight loss, texture profile analysis, titration acidity, pH, water activity, total dry matter amount, total ash amount, color and total phenolic content in the samples were monitored. In addition, the phenolic profiles and microbial quality of the samples were determined. At the beginning of the present study, the water activity, the dry matter content, ash content, the titration acidity, the pH, and phenolic acid content of fresh mushrooms were found as 0.96, 11.90%, 1.51%, 0.28%, 6.35, and 541.83 mg GAE/kg, respectively. In addition, the color values were determined as 93.66, -0.39 and 10.77 for L*, a* and b*, respectively. The textural parameters were calculated as 2222.22 g for hardness, 0.92 for elasticity, 1646.13 for gumminess, 1441.83 for chewiness. At the end of the storage, the highest weight loss was determined as 1.63% in the samples packaged with the gas containing 5% O2-5% CO2. According to the results of microbiological analysis of mushroom samples, the initial loads of the molds and yeast, mesophilic aerobic and psychrophilic aerobic bacteria were found as 4.68 log cfu/g, 6.40 log cfu/g, and 6.25 log cfu/g and 4.68 log cfu/g, respectively. At the end of the storage MA, the lowest total number of mesophilic and psychrophilic aerobic bacteria, yeast and molds were determined in the samples packaged with 3% O2-8% CO2. The mushroom samples packaged with 3% O2-5% CO2 preserved their initial quality properties better than the other samples packed with other different gas concentrations. However, at the end of storage with MAP, it was observed that the flesh firmness of the mushrooms decreased in all groups (%5 O2 - %5 CO2, %3 O2 - %8 CO2, %3 O2 - %5 CO2). Among the phenolic compounds in the mushroom samples, catechin was recorded to have the highest amount at 180.22 mg/kg. The water activity, dry matter, ash, titration acidity, pH, and phenolic acid content of the fresh garlic samples were found as 0.93, 44.45%, 1.25%, 0.28%, 7.21, and 327.84 mgGAE/kg, respectively. Color values were determined as 77.98, -2.11 and 12.58 for L*, a* and b*, respectively. The results obtained from the texture profile analysis showed that the hardness, elasticity, gumminess, and chewiness values of the garlic samples were calculated as 4483.35 g, 0.73, 0.66, and 2254.33, respectively. At the end of the storage, the highest weight loss with a value of 8.08% was observed in the samples packaged with the MAP condition containing 5% O2-5% CO2. In addition, the higher quantities of phenolic compounds detected in garlic samples were recorded for catechin as 13.08 mg/kg and vanillin at 10.42 mg/kg. In addition, the initial loads of total mesophilic and psychrophilic aerobic bacteria, mold and yeast were found as 2.37 log cfu/g, 2.35 log cfu/g, and < 2.0 log cfu/g, respectively. At the end of storage, the lowest total mesophilic and psychrophilic aerobic bacteria was found in the garlic samples packaged with %3 O2-%5 CO2. In conclusion, the maximum storage period for all gas mixtures used for packaging of kunkor mushroom samples was determined as 9 days. On the other hand, the most suitable packaging condition was determined as the gas mixture containing 5% O2 - 5% CO2 and the most appropriate storage period was 6 weeks for Tunceli garlic samples.