Modelling and Classification of Apple Textural Attributes Using Sensory, Instrumental and Compositional Analyses.

Textural characteristics of fruit are important for their quality, storability, and consumer acceptance. While texture can be evaluated instrumentally or sensorially, instrumental measurements are preferred if they can be reliably related to human perception. The objectives of this research were to validate instrumental measurements with sensory determinations, develop a classification scheme to group apples by their textural characteristics, and create models to predict sensory attributes from instrumental and compositional analyses. The textural characteristics (crispness, hardness, juiciness, and skin toughness) of 12 apple cultivars were evaluated on new and established cultivars. Fruit was also evaluated using five instrumental measurements from TA.XTplus Texture Analyzer, and three compositional determinations. The experiment was repeated for analysis and validation purposes. Principal component (PC) analysis revealed that 95.88% of the variation in the instrumental determinations could be explained by two components (PC 1 and PC 2); which were highly correlated with flesh firmness and skin strength, respectively. Four textural groups of apples were identified, and the accuracy of classification was established at 94.44% by using linear discriminant analysis. The predictive models that were developed between the sensory and instrumental-compositional data explained more than 85% of the variation in the data for hardness and crispness, while models for juiciness and skin toughness were more complex. The work should assist industry personnel to reduce time-consuming and costly sensory testing, yet have an appreciation of the textural traits as perceived by the consumer.

Multiple Correspondence and Hierarchical Cluster Analyses for the Profiling of Fresh Apple Customers Using Data from Two Marketplaces.

Purchase behavior and preferences for consumers of fresh apples were investigated using a consumer survey conducted at a special-event apple market. Survey respondents were asked to list apple cultivars they had purchased at the retail market and the special-event market. The special-event market offered many uncommon cultivars packed in clear plastic bags with a fixed weight and price. Respondents were also asked to identify their reasons for selection of each apple cultivar and answer demographic questions. A total of 169 customers completed the survey. Profiles of customers were identified using multiple correspondence analysis (MCA) and hierarchical cluster analysis (HCA), and the impact of the change in available apple cultivars on consumers' purchase behavior was explored. Consumers primarily indicated four main reasons in the selection of their apples: visual appearance, previous experience, taste/aroma, and texture. The first two reasons, evaluated before eating an apple, were loaded on the first MCA dimension, while the last two reasons (i.e., eating quality) were loaded on the second dimension in data from both marketplaces. HCA identified five classes of customers in both markets, and results indicated that similar market segments existed within the two marketplaces, regardless of the availability of apple cultivars.

Effect of sulfite addition and pied de cuve inoculation on the microbial communities and sensory profiles of Chardonnay wines: dominance of indigenous Saccharomyces uvarum at a commercial winery.

The microbial consortium of wine fermentations is highly dependent upon winemaking decisions made at crush, including the decision to inoculate and the decision to add sulfur dioxide (SO2) to the must. To investigate this, Chardonnay grape juice was subjected to two inoculation treatments (uninoculated and pied de cuve inoculation) as well as two SO2 addition concentrations (0 and 40 mg/L). The bacterial communities, fungal communities and Saccharomyces populations were monitored throughout fermentation using culture-dependent and culture-independent techniques. After fermentation, the wines were evaluated by a panel of experts. When no SO2 was added, the wines underwent alcoholic fermentation and malolactic fermentation simultaneously. Tatumella bacteria were present in significant numbers, but only in the fermentations to which no SO2 was added, and were likely responsible for the malolactic fermentation observed in these treatments. All fermentations were dominated by a genetically diverse indigenous population of Saccharomyces uvarum, the highest diversity of S. uvarum strains to be identified to date; 150 unique strains were identified, with differences in strain composition as a result of SO2 addition. This is the first report of indigenous S. uvarum strains dominating and completing fermentations at a commercial winery in North America.

The effect of sulfur dioxide addition at crush on the fungal and bacterial communities and the sensory attributes of Pinot gris wines.

Modern day winemaking often involves the addition of sulfur dioxide (SO2) at crush to act as both an antioxidant and an antimicrobial agent. While the effects of SO2 on microbial communities and particularly on spoilage microorganisms has been well-studied, the advent of culture-independent molecular technologies, such as Illumina sequencing, allows the subject to be re-visited in a new context. High-throughput amplicon sequencing allows for a more thorough evaluation of microbial communities, as thousands of microbial sequences per sample can be identified and even rare microorganisms can be studied. This research investigated whether the addition of different levels of SO2 at crush (0, 20, or 40 mg/L) would affect the composition of fungal and bacterial communities, as well as the sensory attributes of the resulting wines. Samples were taken from uninoculated fermentations of Pinot gris and analyzed via high-throughput amplicon sequencing using the Illumina MiSeq platform. Yeast relative abundance and overall fungal community composition differed among the SO2 additions. Notably, a Hanseniaspora yeast appeared in all treatments and persisted until the end of alcoholic fermentation, although its relative abundance was significantly higher in the fermentations to which low or no SO2 had been added. Two key wine sensory attributes (citrus aroma and pome fruit flavor) differed among the SO2 treatments. This research provides an in-depth look into the fungal and bacterial communities during alcoholic fermentation and gives a better understanding of the microbial community response to SO2 additions during the crush period.

Inter-correlation of apple firmness determinations and development of cross-validated regression models for prediction of sensory attributes from instrumental and compositional analyses.

The texture of apples is paramount for determining fruit quality. This research explored the correlations among firmness determinations from the Sinclair iQ™ Firmness Tester (SiQ™), the Aweta Acoustic Firmness Sensor (AFS), and eight measurements from the Mohr Digi-Test-2 (MDT) instrument. Assessments were conducted on a collection of nine apple cultivars (Ambrosia, Aurora Golden Gala™, Honeycrisp, Fuji, Imperial Gala, McIntosh, Pink Lady™, Silken, Salish™), with a broad range of firmness values, in each of two years. Sensory analysis of the apples was conducted using a semi-trained panel (n = 10) to evaluate crispness, hardness, juiciness and skin toughness, in quadruplicate at two testing dates, providing eight data points per cultivar per year. Inter-correlations of the instrumental firmness determinations (SiQ™, AFS, MDT) revealed that most values were highly correlated with one another (r > 0.500 n = 72). This suggested that the instruments were tracking similar, but not identical, underlying characteristics. Multiple regression models were developed using the 2016 data to predict the sensory attributes from the instrumental and compositional (titratable acidity, soluble solids concentration, absorbed juice) analyses. Models with the highest R2 were cross-validated using the 2015 data. Accuracy of these models was evaluated using R2 and prediction standard errors (PSEs) - an index quantifying the difference between the predicted and actual values. In general, simple 1- and 2-variable models satisfactorily predicted hardness and crispness, with the R2 values ranging between 85 and 89%, while more complex non-linear models were required to predict juiciness and skin toughness. Correlations coefficients reported in this research allow for interconversion of experimental firmness data, as determined by the SiQ™, AFS and MDT. Regression models predicting hardness, crispness and juiciness from instrumental/compositional analyses, revealed that the quality factor (QF) variable was particularly important for estimation of textural characteristics. Therefore the MDT, among the instruments evaluated, was the instrument of choice for quality assessment of apples. Since cross-validation of the models accounted for a high proportion of the variance (70-82%) in a new data set with small PSEs (2.67-6.36) (on a 100-unit scale), the developed models were appropriate for estimating the apple textural attributes.

Use of descriptive analysis and preference mapping for early-stage assessment of new and established apples.

BACKGROUND: This research compared four new apple selections with 16 established apples using descriptive analysis (DA), instrumental analyses and preference mapping, in order to identify suitable selections for commercialization and further research. RESULTS: DA revealed that the new apple selections (PARC1, PARC2, PARC3, PARC4) were very similar in texture/mouthfeel (T) but differed in their flavor (F) and appearance (A) characteristics. Preference mapping revealed that consumers' T preferences were driven primarily by crispness, juiciness and lack of skin toughness, while F preferences were driven by sweetness, lack of tartness and presence of fruity flavor. Consumers' A preferences were driven by a high percentage of red color and degree of striping. The majority of consumers had similar T (82-85%) and F (88-92%) preferences for the early- and mid/late-harvest apples. In contrast, consumers' A preferences were differentiated into three subgroups (60%, 24%, 16%) for the early-harvest apples, but not for the mid/late-harvest apples. The new apple selections were among those most liked for T, F and A. CONCLUSION: This early-stage consumer research confirmed that the new apples were comparable, if not superior, to the established apples. As such, it provided the necessary feedback to industry to proceed with commercialization and optimization of cultural and storage practices.

Descriptive and hedonic analyses of low-Phe food formulations containing corn (Zea mays) seedling roots: toward development of a dietary supplement for individuals with phenylketonuria.

BACKGROUND: Seedling roots of anthocyanin-rich corn (Zea mays) cultivars contain high levels of phenylalanine ammonia lyase (PAL) activity. The development of a natural dietary supplement containing corn roots could provide the means to improve the restrictive diet of phenylketonuria (PKU) patients by increasing their tolerance to dietary phenylalanine (Phe). Therefore this research was undertaken to explore the sensory characteristics of roots of four corn cultivars as well as to develop and evaluate food products (cereal bar, beverage, jam-like spread) to which roots had been added. RESULTS: Sensory profiles of corn roots were investigated using ten trained judges. Roots of Japanese Striped corn seedlings were more bitter, pungent and astringent than those of white and yellow cultivars, while roots from the Blue Jade cultivar had a more pronounced earthy/mushroom aroma. Consumer research using 24 untrained panelists provided hedonic (degree-of-liking) assessments for products with and without roots (controls). The former had lower mean scores than the controls; however, the cereal bar had scores above 5 on the nine-point scale for all hedonic assessments compared with the other treated products. CONCLUSION: By evaluating low-Phe food products containing corn roots, this research ascertained that the root-containing low-Phe cereal bar was an acceptable 'natural' dietary supplement for PKU-affected individuals.

Functional characterization of individual- and mixed-Burgundian Saccharomyces cerevisiae isolates for fermentation of Pinot noir.

Pinot noir has traditionally been fermented by native flora of multiple yeasts producing a complex combination of aromas and flavors. With the use of industrial dry yeasts, winemakers gained enological reliability and consistency in their wines, but lost diversity and complexity. This research evaluated the use of co-culturing yeasts to fulfill this dual role. Fermentations of Burgundian Saccharomyces cerevisiae isolates and their mixtures were evaluated for their enological characteristics and production of volatile compounds, at 22 °C and 27 °C. The novel isolates were genetically unique and enologically equivalent to the industrial strains. Analysis of variance and principal component analysis of 25 headspace volatiles revealed differences among the yeasts and between the fermentation temperatures. Wines from the mixed-Burgundian isolates were most similar to one another and could be differentiated from the industrial strains at both 22 °C and 27 °C. Mixed-Burgundian wines at both temperatures had higher concentrations of ethyl esters and acetate esters, compared to the industrial strains which had higher concentrations of higher alcohols at 27 °C and higher concentration of other ethyl esters at 22 °C. Given the unique profiles of the co-cultured wines, this research offers winemakers a strategy for producing wines with unique and more complex characters without the risk of spontaneous fermentations.

Systematic comparison of hedonic ranking and rating methods demonstrates few practical differences.

Hedonic ranking is one of the commonly used methods to evaluate consumer preferences. Some authors suggest that it is the best methodology for discriminating among products, while others recommend hedonic rating. These mixed findings suggest the statistical outcome(s) are dependent on the experimental conditions or a user's expectation of "what is" and "what is not" desirable for evaluating consumer preferences. Therefore, sensory and industry professionals may be uncertain or confused regarding the appropriate application of hedonic tests. This paper would like to put this controversy to rest, by evaluating 3 data sets (3 yogurts, 79 consumers; 6 yogurts, 109 consumers; 4 apple cultivars, 70 consumers) collected using the same consumers and by calculating nontied ranks from hedonic scores. Consumer responses were evaluated by comparing bivariate associations between the methods (nontied ranks, tied ranks, hedonic rating scores) using trellis displays, determining the number of consumers with discrepancies in their responses between the methods, and comparing mean values using conventional statistical analyses. Spearman's rank correlations (0.33-0.84) revealed significant differences between the methods for all products, whether or not means separation tests differentiated the products. The work illustrated the inherent biases associated with hedonic ranking and recommended alternate hedonic methodologies.