This study aimed at the application of Wolf formula for structural design of corrugated box for dairy products. Five kinds of corrugated boxes for 350 mL of Momchilovtsi, a Bright Dairy yoghurt brand, were designed according to the capacity and arrangement of the inner packaging, and their theoretical compression strength was calculated using Wolf formula as well as their minimum compression strength when 10 boxes were stacked and stored in the same environment using compression formula. Comparative analysis of the results of both calculations was carried out based on structural design elements such as ratio of length to width and length of sides. Moreover, verification was achieved using compression tests. Finally, we established the optimal structural design of 350 mL corrugated boxes for Momchilovtsi. It was showed that corrugated carton No. 4 had the highest marketability under the conditions: the same material and height, 3 × 3 arrangement mode, length/width ratio of 1, and length of sides of 74 mm.

Three kinds of aluminum-free composite sealing film: F1, polyethylene/low density polyethylene/ethylenevinyl acetate copolymer (PE/LDPE/EVA); F2, polyethylene terephthalate (PET)/PE/EVA; and F3, PET/cast polypropylene (CPP)/ EVA were selected to package yoghurt in polystyrene (PS) cups. Comparison of material characteristics and packaging performance of composite films and the storage life of packaged yoghurt was carried out with respect to fim oxygen permeability, opening force and puncture resistance, and yoghurt sensory evaluation, acidity and storage life. The storage life of yoghurts packaged with F1, F2 and F3 was tested at (30.0 ± 1.5), (25.0 ± 1.5) and (4.0 ± 1.5) ℃, respectively. The results showed that oxygen permeability of F3 was the lowest, 46.602 cm3/(m2·24 h·0.1 MPa), among three kinds of films at the same temperature and humidity, and it had the best oxygen barrier property, while oxygen barrier property of F1 was the lowest. The storage temperature of (4.0 ± 1.5）℃ had less significant impact on the sensory evaluation, acidity or storage life of yoghurt than (30.0 ± 1.5) and (25.0 ± 1.5) ℃ and gave the longest storage life of 7 to 8 days, yielding an acidity higher than 87 °T at the end of the storage life. Under the same storage conditiuons (time and temperature), yoghurt packaged with F3 had the lowest acidity and exhibited the loweest growth rate of acidity and the best sensory evaluation results. In terms of opening force, only F2 and F3 met the packaing requirements for yoghurt. F1 had very high puncture resistance while F3 was the easiest to puncture with an ease level of 85%. Together, the above fingdings demonstrate that PET/CPP/EVA film is the most suitable sealing film for packaging yoghurt in cups, which achieves the longest storage life of 8 days at (4.0 ± 1.5) ℃ and meets the packaging requirements for yoghurt.