Karen L. Bett-Garber

Sensory Characteristics of Diverse Rice Cultivars as Influenced by Genetic and Environmental Factors

ABSTRACT An understanding of how genetic, preharvest, and postharvest factors affect the sensory characteristics of rice will help producers and processors meet the needs of specific customers and foster the development of a diversified rice market. In this study, differences in the texture and flavor of 17 diverse cultivars related to genetic differences were characterized and the stability of their flavor and texture from one crop year to the next was determined. Sensory attributes of cooked rice were measured by panelists using descriptive sensory analysis methodology. Cooked texture of the cultivars varied widely and correlated well with amylose content with correlation coefficient (r) values in the range 0.76–0.97 for 11 of the 14 attributes. Flavor attribute intensities were low and similar among cultivars, with the exception of grain flavor. Grain flavor ranged in intensity from 2.2 to 4.9 and correlated highly and negatively with amylose content (-0.88). Roughness and hardness were the only textur...

Important Sensory Properties Differentiating Premium Rice Varieties

In rice-consuming countries, specific varieties are recognized as premium, “gold standard” varieties, while others are recognized as being superior but second best, despite being identical using the current suite of tools to evaluate quality. The objectives of this study were to determine if there are distinguishable differences in sensory properties of premium and second best varieties and whether these differences are common to premium varieties. Color, an important sensory property, was determined on the raw and cooked rice using a colorimeter. As raw rice, some of the premium varieties were whiter than their second best counterparts while others were not. However, when cooked, with two exceptions, the premium varieties were of the same or greater whiteness than their counterparts. A trained sensory panel employed descriptive sensory analysis, an objective tool, to characterize and analytically measure the flavor (aromatics, taste, mouthfeel) and texture of premium and second best varieties collected from nine rice-consuming countries. Sweet taste, popcorn aroma/flavor, and water-like metallic mouthfeel showed significant differences in intensity between the premium–second best variety pairs. Slickness, roughness, and springiness were the major traits that distinguished the texture of varieties. Quality evaluation programs do not routinely measure these texture and flavor traits, but the fact that they distinguished the varieties in most pairs indicates that their measurement should be added to the suite of grain quality tests in the development of new higher-yielding, stress-tolerant varieties. The incorporation of premium quality will ensure that quality is no impediment to widespread adoption leading to enhanced productivity and food security.

Effects of Organic Fertility Management on Physicochemical Properties and Sensory Quality of Diverse Rice Cultivars

ABSTRACT The demand for organically grown rice has increased with consumer demand for organic foods. The objective of this research was to determine whether there are physicochemical differences in organically and conventionally grown rice that contribute to flavor and texture differences, as determined by descriptive sensory analysis, an objective tool. Five diverse cultivars (four nonwaxy and one waxy) were grown at Beaumont, TX, with 100 or 50% recommended nitrogen fertilizer using conventional management or with chicken litter using organic management. Mean protein content differed significantly (P < 0.05) with fertilizer input, whereas mean apparent amylose and mineral contents (with few exceptions) did not differ. The mean protein content of each cultivar grown with the 100% N rate typically used was significantly higher (P < 0.05) than that of the cultivar grown organically or at the 50% N rate. The mean protein contents of the cultivars grown organically and at the 50% N rate did not significantly...

Unraveling the Impact of Nitrogen Nutrition on Cooked Rice Flavor and Texture

ABSTRACT Understanding the influences of amylose and protein contents on rice sensory properties is key to maintaining quality and providing consumers with rice with desired flavor and textural attributes. This research focused on delineating the effects of nitrogen nutrition on cooked rice texture and flavor. The sensory properties of cultivars grown in adjoining fields with differing rates of nitrogen fertilizer (to yield grains with a large spread in protein contents) were measured by a panel trained in descriptive analysis. Second, rice sensory properties were modeled using apparent amylose and protein data. Fertilizer level affected protein and apparent amylose contents and, in turn, cooked rice texture. Protein contents were significantly higher (P < 0.0007) and apparent amylose contents were significantly lower (P < 0.0001) at the higher fertilizer level. Models revealed a negative correlation of protein content with initial starchy coating, slickness, and stickiness between grains—three attributes...

Effects of drain and harvest dates on rice sensory and physicochemical properties

ABSTRACT Timing of field draining and harvesting of rice with meteorological conditions can allow growers to foster conditions for high head rice yield (HRY). The effects of timing of draining and harvesting on rice sensory and physicochemical properties are not well understood. The objective of this study was to determine the effects of varying drain and harvest dates on the sensory and physicochemical properties of M-202 grown in California under controlled field conditions. Drain date had a significant (P 0.05) differences in texture were measured as a result of these parameters being low. Drain date did not affect the volatile composition or flavor of the rice. Harvest date had no effect (P > 0.05) on amylose content and a sig...

Impact of Storage of Freshly Harvested Paddy Rice on Milled White Rice Flavor

ABSTRACT Between harvest and the start of drying, paddy rice may be held for more than 24 hr at moisture contents ranging from 16% to >26%. Microbes found on the freshly harvested rice grow under these conditions and produce a wide variety of volatile compounds that impact the flavor/aroma of the white rice obtained after drying and milling of the paddy rice. The contents of 10 volatile microbial metabolites were compared in white rice obtained from paddy rice harvested at differing moisture contents and immediately dried (0 hr) or held for 48 hr before drying. No increases in volatile microbial metabolite levels were observed in white rice obtained from paddy rice that was stored at 17–21% moisture contents for 48 hr. In white rice from paddy rice stored at ≥24% moisture content, 3-methyl-butanol, 2-methyl-butanol, acetic acid, 2,3- butandiol, and ethyl hexadecanoate increased markedly with time. Also in these samples, as determined by a descriptive panel, sour/silage and alfalfa/grassy/green bean flavor...

Near-Infrared Reflectance Analysis for Prediction of Cooked Rice Texture

ABSTRACT The ability of near-infrared (NIR) spectroscopy to predict sensory texture attributes of diverse rice cultivars was examined. The sensory texture of 87 samples representing 77 different short-, medium-, and long-grain cultivars was evaluated by trained panelists using descriptive analysis. Correlations between sensory texture attributes and NIR reflectance data were examined using the multivariate method of partial least squares (PLS) regression. Texture attributes (hardness, initial starchy coating, cohesiveness of mass, slickness, and stickiness) measured by panelists in the early evaluation phases were successfully predicted (R2calibration 0.71–0.96). Cohesiveness of mass, the maximum degree to which the sample holds together in a mass while chewing, was best modeled with R2calibration = 0.96 and R2validation = 0.90. Key wavelengths contributing to the models describing the texture attributes were wavelengths also contributing to models for amylose, protein, and lipid contents.

Volatile, anthocyanidin, quality and sensory changes in rabbiteye blueberry from whole fruit through pilot plant juice processing

BACKGROUNDnHigh antioxidant content and keen marketing have increased blueberry demand and increased local production which in turn mandates new uses for abundant harvests. Pilot scale processes were employed to investigate the anthocyanidin profiles, qualitative volatile compositions, and sensorial attributes in not-from-concentrate (NFC) Tifblue rabbiteye blueberry juices.nnnRESULTSnProcessing prior to pasteurization generally resulted in increased L* and hue angle color, while a* , b* , and C* decreased. After 4 months pasteurized storage, non-clarified juice (NCP) lost 73.8% of total volatiles compared with 70.9% in clarified juice (CJP). There was a total anthocyanidin decrease of 84.5% and 85.5% after 4 months storage in NCP and CJP, respectively. Storage itself resulted in only 14.2% and 7.2% anthocyanidin loss after pasteurization in NCP and CJP. Storage significantly affected nine flavor properties in juices; however, there were no significant differences in the blueberry, strawberry, purple grape, floral, sweet aroma, or sweet tastes between processed and stored juices.nnnCONCLUSIONSnNFC pasteurized blueberry juices maintained desirable flavors even though highly significant volatile and anthocyanidin losses occurred through processing. Maintenance of color and flavor indicate that NFC juices could have an advantage over more abusive methods often used in commercial juice operations.

Flavor of Fresh Blueberry Juice and the Comparison to Amount of Sugars, Acids, Anthocyanidins, and Physicochemical Measurements

Six cultivars of southern highbush (SHB) and rabbiteye (RE) blueberry samples were harvested on 2 different dates. Each treatment combination was pressed 2 times for repeated measures. Fresh juice was characterized for 18 flavor/taste/feeling factor attributes by a descriptive flavor panel. Each sample was measured for sugars, acids, anthocyanidins, Folin-Ciocalteu, soluble solids (BRIX), titratable acidity (TA), and antioxidant capacity (ORACFL ). Flavors were correlated with the composition and physicochemical data. Blueberry flavor correlated with 3 parameters, and negatively correlated with 2. Strawberry correlated with oxalic acid and negatively correlated with sucrose and quinic acid. Sweet aroma correlated with oxalic and citric acid, but negatively correlated with sucrose, quinic, and total acids. Sweet taste correlated with 11 parameters, including the anthocyanidins; and negatively correlated with 3 parameters. Neither bitter nor astringent correlated with any of the antioxidant parameters, but both correlated with total acids. Sour correlated with total acids and TA, while negatively correlating with pH and BRIX:TA. Throat burn correlated with total acids and TA. Principal component analysis negatively related blueberry, sweet aroma, and sweet to sour, bitter, astringent, tongue tingle, and tongue numbness. The information in this component was related to pH, TA, and BRIX:TA ratio. Another principal component related the nonblueberry fruit flavors to BRIX. This PC, also divided the SHB berries from the RE. This work shows that the impact of juice composition on flavor is very complicated and that estimating flavor with physicochemical parameters is complicated by the composition of the juice.

Correlation of Sensory, Cooking, Physical, and Chemical Properties of Whole Grain Rice with Diverse Bran Color

ABSTRACT Whole grain rice is nutrient dense because of the intact bran layer. The literature indicates that there is genetic variability for compounds in the bran layer of whole grain rice with some compounds in high concentrations in varieties with pigmented bran. The purpose of this study was to compare factors that impact sensory characteristics between different classes of rice bran color. Ten varieties, two from each of five bran colors (white, light brown, brown, red, and purple), were evaluated for descriptive flavor and texture, physical characteristics, gelatinization temperature, apparent amylose content, and polyphenols. Rice that has red or purple pigmented bran has higher contents of phenols and flavonoids, and these varieties were strongly correlated with some flavor attributes. The bran/hay/straw attribute correlated with bran weight and bran thickness, and sweet taste negatively correlated with amylose content. The texture attribute of hardness was significantly different among bran colors...