Innovations in milk packaging: Effects of bottle design and storage arrangement on milk quality.

Milk consumption has decreased in recent years, putting greater emphasis on packaging solutions that enhance consumer appeal while maintaining product quality. Because light exposure accelerates photooxidation, package design and material selection are critical for keeping milk fresh. This study evaluated how milk bottle shape and storage arrangement influence photooxidation and consumer sensory perception. Transparent polyethylene terephthalate (PET) bottles (round, square, oblong) were stored at 4°C either individually or grouped, and analyzed on d 0, 4, 7, 10, 12, 14, and 18. Over 18 d, milk samples were tested for peroxide values, thiobarbituric acid reactive substances (TBARS), conjugated dienes, and conjugated trienes. Milk consumers (n = 50-54) evaluated aroma freshness (1-7 scale), liking (9-point hedonic), and aroma attributes (rate-all-that-apply), with data analyzed using ANOVA and Tukey's HSD. Bottle shape influenced photooxidation, with oblong bottles displaying higher TBARS values compared with round and square bottles (P < 0.05). Sensory analysis results aligned, with milk in oblong bottles receiving lower ratings for aroma liking and freshness compared with milk in round or square bottles (P < 0.05). More consumers detected sour aromas in milk from oblong bottles but detected dairy aromas in milk from round or square bottles (P < 0.05). Storage arrangement only affected peroxide values; milk bottles stored in an individual arrangement had higher concentrations as storage time progressed (P < 0.05). These findings suggest that bottle shape, but not storage arrangement, affects photooxidation and sensory quality. Packaging with optimized shapes may reduce light-induced degradation while offering appealing designs, potentially supporting increased milk consumption in homes and schools.