Integrated CIELab, electronic nose and GC-MS recognition technology elucidate the effect of oak chip aging on sensory and flavor quality of ciders

Oak chips are cost-effective alternatives to oak barrels to accelerate aging and to modulate sensory profiles in fermented beverages. This study investigated the effects of five commercial oak chips on the appearance, aroma, and sensory quality of cider during 90 days of aging at 20 °C. Color (CIELab), transmittance, and turbidity were used to evaluate appearance, while aroma characteristics were analyzed by electronic nose and HS-SPME-GC-MS, followed by sensory evaluation. Oak chip aging intensified color and increased visual differentiation among samples. The AM16 treatment showed the greatest decrease in transmittance (0.6%) and the highest turbidity, whereas 8HT resulted in the highest redness (a* = 0.45). Principal component analysis (PCA) analysis of the electronic nose data explained more than 95% of the total variance and clearly distinguished the AM16-treated cider, indicating a unique aroma profile. A total of 24 volatile compounds were identified in oak-aged ciders, including seven compounds absent in the control (e.g., furfural). Ester levels increased, while higher alcohols decreased after aging. Sensory analysis confirmed these trends, with 8HT-treated cider achieving the highest overall acceptance (89.9/100), characterized by enhanced aroma complexity and balanced mouthfeel. These results highlight the key role of oak chip type in optimizing cider quality.