Flavor lexicon for sensory descriptive profiling of different rice types.

Rice flavor is a significant factor in determining quality and consumer acceptability as exemplified by scented rice, which is highly favored and commands a price premium. Sensory descriptive analysis has primarily been performed to assess rice flavor characteristics, but these studies feature only a limited lexicon for characterizing specific flavors or the range of flavor types is limited. This study was undertaken to establish a descriptive lexicon with reference standards for describing the flavor properties of a broad spectrum of rice types and use the developed lexicon to characterize which sensory attributes are most important in rice flavor quality. A rice flavor lexicon consisting of 24 descriptive notes was developed and expanded by 8 trained sensory panelists to characterize the flavor of cooked rice differing in terms of forms, types, and specialty (n = 36). Of these 24 descriptive terms, 19 were aromatic notes and 5 were fundamental tastes and oral feeling factors. Eighteen aromatic terms were significantly present in most rice samples whereas some descriptors exhibited unique characteristics of a specific-rice type. Subsequent multivariate analysis indicated that 18 descriptive terms were required to fully understand the characteristics of rice flavor in greater details. This lexicon covered a wider range of rice samples than in the previous studies and will facilitate targeting the characteristic notes important to rice processors as well as producers.

Relating sensory descriptors to volatile components in flavor of specialty rice types.

Flavor is a key factor contributing to consumer acceptance and repeat purchase of rice. Plant breeders focus on production yield and ignoring quality traits because there are no readily useable tools to evaluate quality. A systematic approach is needed for rice breeders to select rice with favorable flavor traits. Descriptive sensory analysis combined with chemical analysis provided an insight of sensory significance to interpret chemical data for a better understanding approach of rice flavor. This study was aimed to develop prediction models for sensory descriptors based on the volatile components derived from the gas chromatography-olfactometry (GC-O) that would be useful to help select rice cultivars containing a satisfactory flavor to produce improved quality in rice breeding programs. Thirteen Korean specialty rice samples were evaluated for their flavor components using descriptive analysis and GC-O. Nineteen aroma attributes in cooked specialty rice samples were evaluated by 8 trained panelists and statistically correlated to the concentration of aroma-active compounds derived from GC-O analysis. Prediction models were developed for most aroma descriptors including popcorn, cooked grain, starchy, woody, smoky, grain, corn, hay-like, barny, rancid, waxy, earthy, and sweet aroma using stepwise multiple linear regression. (E,E)-2, 4-decadienal, naphthalene, guaiacol, (E)-2-hexenal, 2-acetyl-1-pyrroline, 2-heptanone contributed most to these sensory attributes. These models help provide a quantitative link between sensory characteristics of commercial rice samples and aroma volatile components desirable in developing a rapid analytical method for use by rice breeders to screen progeny for superior flavor quality.

Home-style beef jerky: effect of four preparation methods on consumer acceptability and pathogen inactivation.

The safety of homemade jerky continues to be questioned. Producing a safe product that retains acceptable quality attributes is important. Lethality of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes as well as consumer acceptability and sensory attributes of jerky prepared by four methods were examined. Preparation methods were drying marinated strips at 60 degrees C (representing a traditional method), boiling strips in marinade or heating in an oven to 71 degrees C prior to drying, and heating strips in an oven after drying to 71 degrees C. A 60-member consumer panel rated overall acceptability. A 10-member descriptive panel evaluated quality attributes. Samples heated after drying and samples boiled in marinade prior to drying had slightly higher acceptability scores but were not statistically different from traditional samples. Although the four treatments were significantly different in color (P = 0.0001), saltiness (P = 0.0001), and texture (P = 0.0324), only texture appeared to influence overall consumer acceptability. Microbial challenge studies subjecting the pathogens to the four treatments showed a 5.8-, 3.9-, and 4.6-log reduction of E. coli O157:H7, L. monocytogenes, and Salmonella, respectively, even with traditional drying. Oven treatment of strips after drying was shown to have the potential to reduce pathogen populations further by approximately 2 logs. In conclusion, a safer, yet acceptable home-dried beef jerky product can be produced by oven-heating jerky strips after drying.

Detection of guaiacol produced by Alicyclobacillus acidoterrestris in apple juice by sensory and chromatographic analyses, and comparison with spore and vegetative cell populations.

Spoilage of fruit juice by Alicyclobacillus acidoterrestris is characterized by a distinct medicinal or antiseptic off odor attributed to guaiacol, a metabolic by product of the bacterium. Detection of low populations of A. acidoterrestris that would precede sensory detection of guaiacol would enable juice processors to select appropriate processing and storage conditions that would minimize or eliminate spoilage. The objective of this study was to determine the recognition threshold of guaiacol in apple juice by sensory analysis and the population of A. acidoterrestris and incubation time at 21 and 37 degrees C necessary for chemical detection of guaiacol. Commercially sterilized apple juice (pH 3.54 +/- 0.04, 11.3 +/- 0.3 degrees Brix) was inoculated with a five-strain mixture of A. acidoterrestris spores (2.98 log10 CFU/ml) and stored at 21 or 37 degrees C for up to 61 days. Using an experienced sensory panel and the forced-choice ascending concentration method of limits, the best estimate threshold (BET) for recognition of guaiacol added to uninoculated apple juice was 2.23 ppb. Numbers of A. acidoterrestris spores and cells in inoculated juice remained constant during the 61-day storage period; however, the panel detected (P < or = 0.01) guaiacol in juice stored at 37 degrees C within 8 days. At three of four sampling times ranging from 13 to 61 days at which the sensory panel detected (P < or = 0.001) guaiacol, concentrations of 8.1 to 11.4 ppb were detected by chromatographic analysis. The panel detected (P < or = 0.1 to P < or = 0.01) guaiacol in five samples stored at 21 to 37 degrees C for 8 to 61 days in which the compound was not detected by chromatographic analyses. It appears that guaiacol content in apple juice inoculated with A. acidoterrestris is not always correlated with numbers of cells, and the limit of sensitivity of chromatographic quantitation of the compound is higher than the BET.

Lipid oxidation in a chicken muscle model system: oxidative response of lipid classes to iron ascorbate or methemoglobin catalysis.

Catalysis by iron ascorbate and activated methemoglobin generated different oxidative responses in chicken muscle model systems. In iron ascorbate systems, large increases in hydroperoxides and thiobarbituric acid-reactive substances (TBARS) occurred during the initial stage of incubation. Thereafter, iron ascorbate catalysis led to a slow increase in the oxidation of triacylglcyerol (TG) and sarcoplasmic reticulum (SR) membrane lipids. By the end of incubation, 24, 36, and 32% of the initial content of n-3 fatty acids in free fatty acids, TG, and SR single-lipid model systems catalyzed by iron ascorbate had been lost. Reduced losses of n-3 fatty acids were observed in the SR and TG fractions (0 and 24%, respectively) when iron ascorbate model systems contained all three lipid fractions (mix). Hydroperoxides and TBARS in model systems catalyzed by activated methemoglobin were characterized by a lag phase during most of the incubation. Consistent with their role as antioxidants, losses of alpha-tocopherol (42-49%), gamma-tocopherol (36-42%), and protein sulfhydryls (41-52%) were observed in model systems catalyzed by activated methemoglobin. SR and mix model systems were 30-50% slower to oxidize than TG model systems when activated methemoglobin served as the catalytic agent.

Black hair follicular dysplasia, an autosomal recessive condition in dogs.

Using histology, a coat color abnormality and the subsequent hair loss were diagnosed as black hair follicular dysplasia. A pedigree analysis of an affected litter and literature review suggests that this is inherited as an autosomal recessive trait. The melanocyte stimulating hormone receptor gene is ruled out by using linkage analysis.

Inactivation of Salmonella montevideo on Tomatoes by Applying Cellulose-Based Edible Films.

The effect of applying edible coatings to mature-green tomatoes on the survival of Salmonella montevideo on the surface and in core tissue was investigated. A hydroxypropyl methylcellulose (HPMC) coating significantly (P ≤ 0.05) reduced the number of viable S. montevideo cells on the surface of tomatoes. However, only about a 2-log-unit reduction was achieved in core tissue. The addition of citric acid, acetic acid, or sorbic acid (0.2 to 0.4%) to HPMC did not substantially enhance bactericidal activity. Concentrations of 72 to 88% ethanol in HPMC were most effective in inactivating S. montevideo on the surface of tomatoes. Inactivation of S. montevideo in core tissue was similar when tomatoes were dipped in 55 to 88% ethanol solutions. Application of HPMC coating retarded the rate of loss of firmness and change in color of tomatoes stored at 20°C for up to 18 days.

The effects of postharvest treatment and chemical interactions on the bioavailability of ascorbic acid, thiamin, vitamin A, carotenoids, and minerals.

All recent health recommendations include admonitions to reduce calories, maintain desirable weight, reduce fat, increase complex carbohydrates, and ensure an adequate intake of nutrients. Such recommendations require that we know not only nutrient composition of foods, but also potential losses and decreased bioavailability due to postharvest treatment and chemical interactions. This article discusses in some detail the reactions of concern that cause such changes and their potential alleviation with several key nutrients. The nutrients discussed were chosen as a result of the conclusions of the Joint Nutrition Monitoring Report of the Department of Health and Human Services and the U.S. Department of Agriculture. Obviously other choices could have been made, but the authors felt that the nutrients chosen--ascorbic acid, thiamin, vitamin A, carotenoids, calcium, and iron--were representative of a key profile of nutrients whose reactivity makes them vulnerable to losses in bioavailability, as well as being noted in the Joint Nutrition Monitoring Report.

Sarcoplasmic reticulum from flounder muscle having improved lipid peroxidative activity.

A procedure for the isolation of sarcoplasmic reticulum from winter flounder (Pseudopleuronectes americanus) resulted in a fraction with a specific activity of lipid peroxidation two to three times that of previous preparations. In addition, good stability of the NADH-dependent lipid peroxidative activity was achieved. There appeared to be minimal contamination of the preparation with lysosomes and mitochondria. The flounder sarcoplasmic reticulum was highly active with respect to ATPase and calcium uptake. The membrane fraction contained 43% lipid and 57% protein; 60% of the lipids were phospholipids. Phosphatidylcholine was the major phospholipid present.

Inhibition of enzymic and non-enzymic lipid peroxidation of flounder muscle sarcoplasmic reticulum by pretreatment with phospholipase A2.

Sarcoplasmic reticulum, isolated from the muscle of winter flounder (Pseudopleuronectes americanus), was preincubated with phospholipase A2 to determine the effects of enzymic and non-enzymic lipid-peroxidation systems. Eicosapentaenoic acid (20:5) was preferentially released by phospholipase A2, but the percentage of docosahexaenoic acid (22:6) in the free fatty acids was similar to the percentage in membrane total fatty acids. A decrease in the production of both thiobarbituric acid-reactive substances and lipid hydroperoxides was observed in both the enzymic and non-enzymic peroxidation systems upon preincubation with phospholipase A2. Addition of palmitic acid or lysophosphatidylcholine did not inhibit either peroxidation system. Non-enzymic peroxidation was inhibited by the addition of beta-glycerophosphate, but enzymic peroxidation was apparently unaffected. A model is proposed to explain the inhibitory effect of phospholipid hydrolysis on lipid peroxidation in both systems, suggesting that fatty acids are structurally realigned upon hydrolysis, leading to decreased free-radical chain propagation. Additional factors appear to contribute to inhibition of enzymic peroxidation.