Consumers are becoming increasingly aware of the health benefits of dairy ingredients. However, products fortified with dairy proteins are experiencing considerable aroma challenges. Practices to improve the flavor quality of dairy proteins require a comprehensive understanding of the nature and origins of off-aroma. Unfortunately, existing information from the literature is fragmentary. This review presents sensory lexicons and chemical structures of off-aromas from major dairy ingredients, and it explores their possible precursors and formation mechanisms. It was found that similar chemical structures often contributed to similar off-aroma descriptors. Lipid degradation and Maillard reaction are two primary pathways that commonly cause aroma dissatisfaction. Traditional and novel flavor chemistry tools are usually adopted for off-aroma measurements in dairy ingredients. Strategies for improving aroma quality in dairy derived products include carefully selecting starting materials for formulations, and actively monitoring and optimizing processing and storage conditions.

Not from concentrate (NFC) and from concentrate (FC) commercially available orange juices were kept in storage for 8 weeks at 5C. One group of FC and NFC orange juice was stored with minimal headspace, whereas the other group was stored in the presence of oxygen. Weekly analysis of volatile concentrations in samples with selected ion flow tube mass spectrometry showed that most volatiles decreased over the period of the study. There were no significant differences in volatile concentrations between samples that were stored with minimal oxygen exposure and samples that were opened and exposed to oxygen each week. NFC samples had a significantly higher volatile concentration than FC samples from the same manufacturer, but the differences between brands were more pronounced than the difference between NFC and FC. Acetone levels increased in all samples and especially those that were exposed to oxygen. Practical Applications The two sets of storage conditions replicated conditions that the products face while being sold in the market or while used at home by consumers. This study gives orange juice producers a better insight with regard to the aroma and volatile characteristics of their products after their products reach the store shelves. This investigates how the levels of key aromatic volatiles were affected by the presence of oxygen during consumer use and home storage. The data from this study could be used by orange juice manufacturers for quality control or product development purposes.