Lipase-catalyzed modification of structural properties and sensory profile of recombined skim milk: From a non-volatile perspective

Construction of a Pickering interfacial biocatalysis system in skim milk and enzymatic transesterification for enhancement of flavor and quality

Despite considerable research efforts, lipase catalysis in a fluid milk system with aqueous multi-component mixtures containing multiple microphases, remains challenging. Pickering interfacial biocatalysis (PIB) platforms are typically fabricated with organic solvents/lipids and water. Whether a PIB with excellent catalytic performance can be constructed in complex milk mixtures remains unknown. Here, we challenged PIB with skim milk, and a small amount of flaxseed oil, and phytosterols as a model system for transesterification and lipolysis to enhance quality and flavor. The amino-modified mesoporous silica spheres (MSS-N) were employed as an emulsifier and carrier of lipase AYS (AYS@MSS-N). The conversion of phytosterol esters reached 75.5% at 1.5 h and prepared phytosterol ester-fortified milk with a content of 1.0 g/100 mL. The relative conversion rate remained above 70% after 6 cycles. In addition, the fortified milk showed an intensified and favorable effect on sensory traits through volatile flavor composition analysis. The findings provide a versatile alternative for PIB applications in complex environments, i.e., milk, which might inspire a new bioprocess strategy for dairy products.

Sensory Evaluation and Model Prediction of Vacuum-Packed Fresh Corn during Long-Term Storage

The postharvest shelf life of fresh corn largely depends on the packaging method and storage temperature. This study investigated the effect of vacuum packaging (VP) with high-barrier (HB) or ordinary (OR) nylon/nylon/polypropylene (PP) composite films and the impact of storage temperature (4, 25, and 38 °C) on the shelf life of fresh corn. The sensory quality and color changes of the corn were evaluated, indicating a significant improvement in the glossiness (GL), sourness (SO), and color changes compared to corn packaged using OR films. The results showed that the HB films preserved corn freshness under refrigerated and normal temperature storage conditions, delaying color changes and SO development. A shelf-life model was established based on the Arrhenius equation. The predicted values of the corn at different temperatures were compared with the experimental data, indicating that the model could accurately predict the shelf life. The shelf life observed via sensory evaluation was more than 50% shorter than the results obtained by instrumental measurements. Therefore, sensory evaluation could be applied to determine shelf life and avoid food waste.

Sensory Description and Consumer Hedonic Perception of Ultra-High Temperature (UHT) Milk

Sensory characteristics of products play an essential role on the consumer’ s acceptability, preference and consuming behavior choice. The sensory profiles and consumer hedonic perception for 14 UHT milk products using sensory quantitatively descriptive analysis and a 9-point hedonic scale were investigated in this study. There were significant differences in the sensory attributes intensity and liking scores among the organic whole milk, ordinary whole milk, low-fat milk, and skimmed milk (p < 0.05). Skimmed milk samples had lowest intensity scores of typical milk aroma, taste flavor and texture attributes, as well as had the lowest overall liking scores. Whole milk samples had higher sensory intensity scores than low-fat milk samples, even though no significant differences of overall liking scores were observed between whole milk and low-fat milk. Furthermore, the relationship between the sensory attribute and overall liking was demonstrated according to correlation analysis and partial least squares regression (PLSR) analysis. Overall liking increased significantly with the increasing of sweet, after milk aroma, protein-like, mellow and thick, while decreased significantly with the enhancement of cowy, cooked and whey (p < 0.05). These findings presented a potential strategy for identifying the key sensory attributes responsible for liking score differences among different kinds of UHT milk products.