The effect of intense pulsed light on the sensory properties of nonfat dry milk.

Our objectives were to examine (1) how intense pulsed light (IPL) processing parameters (exposure time and initial temperature) affected aroma, flavor, and mouthfeel of nonfat dry milk, (2) which levels of each parameter produced aroma, flavor, and mouthfeel changes from an untreated control sample, and (3) whether minimal or intense processing conditions produced a noticeable appearance change from the control. Four exposure times (1, 2, 3, and 4 passes through the IPL chamber) and three initial temperatures (25, 30, and 35℃) were studied with untreated milk powder as the control. The samples were prepared as both milk powder and reconstituted milk for sensory evaluation. Using standard evaluating protocols, trained descriptive analysis panelists rated the aroma, flavor, and mouthfeel of these samples. Panelists compared the appearance of the IPL-treated samples that underwent a minimal or intense processing condition to the control by using a two-out-of-five difference test. Increasing the exposure time led to increased intensities of overall flavor, burnt flavor, and umami taste in both milk powder and reconstituted milk, while increasing temperature increased animal and sulfur aromas in reconstituted milk only. Compared to the control, all levels of exposure time at any initial temperature resulted in increased aroma and flavor including cardboard aroma, sulfur aroma, and brothy flavor in both milk powder and reconstituted milk. Only the 4-pass exposure at the initial temperature of 25℃ changed the appearance of milk powder. However, the appearance change was not noticeable in reconstituted milk. PRACTICAL APPLICATION: The standard evaluation protocols and lexicons provide useful tools for research on milk powder. Additionally, the understanding of critical factors impacting sensory properties will contribute to a better implementation of this decontamination technology.

The use of a combination of instrumental methods to assess change in sensory crispness during storage of a "Honeycrisp" apple breeding family.

Loss of crispness in apple fruit during storage reduces the fruit's fresh sensation and consumer acceptance. Apple varieties that maintain crispness thus have higher potential for longer-term consumer appeal. To efficiently phenotype crispness, several instrumental methods have been tested, but variable results were obtained when different apple varieties were assayed. To extend these studies, we assessed the extent to which instrumental measurements correlate to and predict sensory crispness, with a focus on crispness maintenance. We used an apple breeding family derived from a cross between "Honeycrisp" and "MN1764," which segregates for crispness maintenance. Three types of instrumental measurements (puncture, snapping, and mechanical-acoustic tests) and sensory evaluation were performed on fruit at harvest and after 8 weeks of cold storage. Overall, 20 genotypes from the family and the 2 parents were characterized by 19 force and acoustic measures. In general, crispness was more related to force than to acoustic measures. Force linear distance and maximum force as measured by the mechanical-acoustic test were best correlated with sensory crispness and change in crispness, respectively. The correlations varied by apple genotype. The best multiple linear regression model to predict change in sensory crispness between harvest and storage of fruit of this breeding family incorporated both force and acoustic measures. PRACTICAL APPLICATIONS: This work compared the abilities of instrumental tests to predict sensory crispness maintenance of apple fruit. The use of an instrumental method that is highly correlated to sensory crispness evaluation can enhance the efficiency and reduce the cost of measuring crispness for breeding purposes. This study showed that sensory crispness and change in crispness after storage of an apple breeding family were reliably predicted with a combination of instrumental measurements and multiple variable analyses. The strategy potentially can be applied to other apple varieties for more accurate interpretation of crispness maintenance measured instrumentally.

Astringency of foods may not be directly related to salivary lubricity.

UNLABELLED: Astringency, a tactile sensation felt in the mouth after exposure to various foods, is poorly understood. Our objective was to investigate the mechanism of astringency by determining if it was related to a loss of saliva's ability to lubricate mouth surfaces. We used 2 complementary approaches: (1) instrumentally determining if astringents decrease salivary lubricity and (2) determining if human subjects could perceive these changes. Instrumentally measured friction of saliva-tannin mixtures was greater than that of saliva-water mixtures, but these differences were not detectable by human subjects. Adding alum or acid to saliva did not increase friction measured either instrumentally or by human subjects rubbing the mixture between their thumb and fingers. Thus a loss of salivary lubricity is likely not a central mechanism of astringency. PRACTICAL APPLICATIONS: If astringency's mechanism can be elucidated, food producers will gain knowledge that will enable them to manufacture, alter, or treat the food in a way to retain its healthful attributes while minimizing the astringency. This knowledge will also benefit sensory scientists interested in the intensity perceptions of the sensations and will allow them to devise improved methods for the assessment of the attribute.

The role of salivary proteins in the mechanism of astringency.

Understanding astringency has focused on the interaction of tannins with the salivary proline-rich proteins (PRPs), although it remains unclear if other astringents precipitate the PRPs or how this interaction relates to sensory perceptions of astringency. We used 2 approaches to compare how distinct classes of astringent compounds interacted with the salivary PRPs and mucins. Using sodium dodecyl sulfate polyacrylamide gel electrophoresis, we evaluated protein patterns and characterized the salivary proteins present in the supernatants and pellets of pooled saliva assayed with tannin, alum, and hydrochloric acid solutions. Tannins and alum precipitated many of the PRPs, but acid did not. Mucins were precipitated by both the acid and alum, but not by the tannins. From our research, it appears that the precipitation of salivary proteins may be involved in the mechanism of astringency, but the precipitation of PRPs is not requisite for the development of astringency. We also measured mucin and deoxyribonucleic acid content of expectorated solutions of astringents that panelists swished in their mouths to determine if astringency was associated with a loss of oral lubricating films.