Probing the interactions between hardness and sensory of pistachio nuts during storage using principal component analysis.

Instrumental hardness and sensory characteristics of pistachio nuts such as flavor, texture, and overall acceptability were measured in three different packages (atmosphere, vacuum, and oxygen scavenger), at three different conditions temperatures (20, 35, and 50˚C) during 12 weeks' storage. Results showed that the effect of temperature, storage time, and interaction effects of packaging and temperature, and packaging and storage time, and packaging and temperature and stoarge time on instrumental hardness were significant (p < 0.01). In sensory evaluation, the effect of treatments on sensory attributes was not significant. Instrumental hardness and sensory texture had a high correlation with each other. Principal component analysis (PCA) of the data obtained for the samples permitted the reduction of the variables to two principal components, which together explained 60.7% of the total variability.

Partition and release of 21 aroma compounds during storage of a pectin gel system.

The increasing popularity of low-fat products increases the need for a better understanding of how flavor release is affected by partial substitution of fat with hydrocolloids. Partitioning and release of aroma compounds from four pectin gels with different compositions were studied with static headspace and with a model mouth. Air/product partition coefficients determine the potential extent of aroma release, and mass transfer determines the rate at which aroma compounds are released to the vapor phase. This study showed that the gel network had large effects on the partition of aroma compounds between the gel and vapor phase. The specific properties of the aroma compounds were also of importance for the air/gel partition. Storage of the four gels showed that one of the weaker gels was influencing the concentration of aroma compounds in the headspace, probably caused by formation of a denser network over time.

Multivariate analysis of the influence of pectin, white syrup, and citric acid on aroma concentration in the headspace above pectin gels.

Pectin gels consist of polysaccharide networks surrounded by water. The gel networks can prevent release of aroma molecules from the gel to the gas phase above. In this study static headspace measurements were performed to correlate aroma concentration in the gas phase above pectin gels to different amounts of the gel ingredients. As a consequence, aroma concentration in the headspace in relation to gel texture, as characterized by rheology measurements, was also studied. Aroma concentration in the headspace above strong gels was low, due to entrapment of aroma molecules within the gel structure. Viscous solutions generally gave a high aroma concentration in the headspace, but owing to a complex matrix, this was lowered when large amounts of the gel ingredients were added. However, a high correlation between interaction terms and square terms of design variables and rheology parameters with aroma compounds indicated nonlinear and complex relationships.