Astringency and its sub-qualities: a review of astringency mechanisms and methods for measuring saliva lubrication

Astringency is an important mouthfeel attribute that influences the sensory experiences of many food and beverage products. While salivary lubricity loss and increased oral friction were previously believed to be the only astringency mechanisms, recent research has demonstrated that nontactile oral receptors can trigger astringency by responding to astringents without mechanical stimulation. Various human factors have also been identified that affect individual responses to astringents. This article presents a critical review of the key research milestones contributing to the current understanding of astringency mechanisms and the instrumental approaches used to quantify perceived astringency intensity. Although various chemical assays or physical measures mimic in-mouth processes involved in astringent mouthfeel, this review highlights how one chemical or physical approach can only provide a single measure of astringency determined by a specific mechanism. Subsequently, using a single measurement to predict astringency perception is overly idealistic. Astringency has not been quantified beyond the loss of saliva lubrication; therefore, nontactile receptor-based responses must also be explored. An important question remains about whether astringency is a single perception or involves distinct sub-qualities such as pucker, drying, and roughness. Although these sub-quality lexicons have been frequently cited, most studies currently view astringency as a single perception rather than dividing it into sub-qualities and investigating the potentially independent mechanisms of each. Addressing these knowledge gaps should be an important priority for future research.

Biodegradability of Gel-Forming Superabsorbents for Soil Conditioning: Kinetic Assessment Based on CO2 Emissions

Quantification of the biodegradability of soil water superabsorbents is necessary for a reasonable prediction of their stability and functioning. A new methodological approach to assessing the biodegradability of these polymer materials has been implemented on the basis of PASCO (USA) instrumentation for continuous registration of kinetic CO2 emission curves in laboratory incubation experiments with various hydrogels, including the well-known trade brands Aquasorb, Zeba, and innovative Russian Aquapastus composites with an acrylic polymer matrix. Original kinetic models were proposed to describe different types of respiratory curves and calculate half-life indicators of the studied superabsorbents. Comparative analysis of the new approach with the assessment by biological oxygen demand revealed for the first time the significance of CO2 dissolution in the liquid phase of gel structures during their incubation. Experiments have shown a tenfold reduction in half-life up to 0.1-0.3 years for a priori non-biodegradable synthetic superabsorbents under the influence of compost extract. The incorporation of silver ions into Aquapastus innovative composites at a dose of 0.1% or 10 ppm in swollen gel structures effectively increases their stability, prolonging the half-life to 10 years and more, or almost twice the Western stability standard for polymer ameliorants.

Modeling of global skin aging indices among Caucasian and Asian women

BACKGROUND

The skin aging process is defined as the gradual degradation of several skin properties such as firmness, color, or the appearance of wrinkles. These properties can be assessed by trained experts, who perform an overall evaluation of the entire face.

OBJECTIVE

The objective of this paper is the construction of two Global Skin Aging Indices specifically designed to model the overall skin aging process of Caucasian and Asian women.

METHODS

Two hundred forty Asian women and 129 Caucasian women aged between 20 and 60 years old are recruited. Parameters related to wrinkles, sagging, elasticity, and skin tone are measured (clinically or instrumentally). The global skin aging index is defined as the normalized projection on the first principal component of a principal component analysis of the skin measurements. Then, linear regressions are performed between the indices and age of both panels.

RESULTS

The first principal component carries around 50% of the initial variance for both indices. Both Global Skin Aging Indices statistically correlate with age (R2 ≥ 0.7, p-value < 0.05). An equation linking the indices with age is computed.

CONCLUSION

The proposed indices are good indicators of the overall aging process for Caucasian and Asian women. They offer new approaches to assess antiaging product efficacy.

Artifacts and errors in the measurement of the stickiness of liquid foods with tack tests

We encounter stickiness in many areas of our daily life and as humans, we are able to discriminate different levels of stickiness. Yet attempts to measure stickiness with instruments have been challenging. One of the commonest approaches has been the "tack test" in which a probe is brought into contact with the sticky food and then pulled away while measuring the resisting force-various indices, such as the maximum force or the area below the force curve have been used to describe stickiness. This work rationalizes results from tack tests for liquid foods and helps us explain the influence of probe geometry. Photographic evidence of the way that the liquid adheres/detaches from the probe suggests that the terms "cohesive" and "adhesive" failure depend on the speed of the test. Application of a fixed deformation with time shows rapid loss of adhesive force suggesting that liquid samples flow from the probe. We propose that stickiness of liquid foods is entirely due to the liquid's viscosity and surface tension, and that measurements of tack for liquid foods-while highly reproducible-are entirely artifacts of the test method employed and are in effect snapshots in time of non-equilibrium processes.

Understanding and predicting sensory crispness of deep-fried battered and breaded coatings

Crusted crispness refers to coatings with a dry and brittle surface contrasting a high‐moisture core; it is desirable for the enjoyment and quality of deep‐fried goods. This study aims to investigate instrumental measurements and sensory measurements of crispness. Deep‐fried breadcrumb coatings of eight sizes were investigated: 4.0 mm, 2.8 mm, 2.0 mm, 1.4 mm, 1.0 mm, 710 μm, 500 μm, and 355 μm. Sensory profiling was carried out to develop a tailored lexicon for deep‐fried battered and breaded shrimp. Principal component analysis highlights that large breadcrumb sizes correlate with crispness, hardness, particle size, surface color, color uniformity, surface irregularity, total porosity, maximum force, area, drop in force, number of sound peaks, and sound pressure level. Agglomerative hierarchical clustering was used to confirm clustering of samples according to breadcrumb size. Multiple factor analysis confirmed overall correlation between sensory measurements and instrumental measurements (RV = 0.810). Partial least squares regression was used to develop a predictive model for crispness from instrumental measurements (R² = .854). The use of texture analysis and Acoustics provide information of the structures strength and deformation behavior, while X‐ray microCT provides a high resolution and noninvasive method that acquires information on the internal morphology. These instrumental methods collectively demonstrate the relationship between microstructure to sensory. This study investigates how a change in the microstructure of deep‐fried battered and breaded coatings affect crispness perception. These changes were investigated analytically and by using a sensory panel, this is important from a manufacturing perspective in order to understand what the major contributors are to a crisp texture. The key highlights of this study include both instrumental measurements and sensory measurements can be used to measure crispness as both types of testing are correlated. Changes in the size of breadcrumbs affect both instrumental measurements and sensory measurements. A predictive model can be re‐simulated to allow prediction of crispness in deep‐fried battered and breaded coatings.