I am an old man in search of a mechanism for perception and how it creates bliss. I may not see answers to these questions in my brief future but I know that I will be looking for them until ...
SUMMARY —The conversion of glutamine to the bitter compound, 2‐pyrrolidone‐5‐carboxylic acid (PCA... more SUMMARY —The conversion of glutamine to the bitter compound, 2‐pyrrolidone‐5‐carboxylic acid (PCA), in table beets was studied. Glutamine was analyzed by a phosphate‐buffer hydrolysis and distillation method. PCA was extracted with ethyl acetate and the ditrimethylsilyl derivative prepared and measured quantitatively by gas‐liquid chromatography. The accumulation of glutamine in fresh beets with excessive amounts of nitrogen fertilization caused a substantial increase in PCA content of processed beets. Conversion of glutamine to PCA in beets was proportional to the heating time during processing. Glutamine content did not alter during raw beet storage periods at 35°F; PCA content increased gradually.
Proteins are the servants of life. They occur in all component parts of living organisms and are ... more Proteins are the servants of life. They occur in all component parts of living organisms and are staggering in their functional variety, despite their chemical similarity. Even the simplest single-cell organism contains a thousand different proteins, fulfilling a wide range of life-supporting roles. Their production is controlled by the cell's genetic machinery, and a malfunction of even one protein in the cell will give rise to pathological symptoms. Additions to the total number of known proteins are constantly being made on an increasing scale through the discovery of mutant strains or their production by genetic manipulation; this latter technology has become known as protein engineering. The in vivo functioning of proteins depends critically on the chemical structure of individual peptide chains, but also on the detailed folding of the chains themselves and on their assembly into larger supramolecular structures. The molecules and their functional assemblies possess a limited in vitro stability. Special methods are required for their intact isolation from the source material and for their analysis, both qualitatively and quantitatively. Proteins are also increasingly used as "industrial components," e.g., in biosensors and immobilized enzymes, because of their specificity, selectivity, and sensitivity. This requires novel and refined processing methods by which the protein isolate can be converted into a form in which it can be utilized. This book provides a unified approach to several essential aspects of protein technology: classifications of protein function, both in situ and in the form of isolates, criteria that govern in vitro protein stability limits, methods of detection, isolation and separation from nanogram to tonne quantities, analysis in situ and in the isolated state, and the technology of protein processing for the production of stable preparations for clinical, agricultural, or industrial use. This book is based on material initially prepared for several postexperience courses: "Characterization of Proteins-Their Analysis and Isolation," taught by the authors on behalf of the Center for Professional Advancement in the US and Europe. It is intended for academic, medical, and a wide range of industrial vi Preface research and development scientists who are actively involved in protein isolation, purification, characterization, and the setting and measuring of protein standards of performance. A general survey of the chemical and functional properties of proteins and the economics of protein isolation and processing is followed by a survey of the parameters that circumscribe protein stability in vitro. The next section deals with in vivo characterization, detection, and localization of several important groups of proteins (e.g., peptide hormones and receptors). This is followed by several chapters describing chromatographic, electrophoretic, and immunological methods employed in the analytical and preparative scale separation, isolation, and characterization of proteinaceous materials, from amino acids through peptide fragments and intact proteins. The final section is devoted to aspects of large-scale processing and quality control methods. This volume differs from most monographs on proteins in that it treats these molecules as valuable but labile chemical raw materials that are easily inactivated by conventional processing techniques. Assuming some previous knowledge of protein analytical, physical, and biochemistry, the book combines these disci P lines to produce a synthesis of the parameters that are essential or the successful isolation, separation, characterization, and stabilization of proteins.
The fatty acid profile from the retronasal aroma of Cheddar cheese was determined using the retro... more The fatty acid profile from the retronasal aroma of Cheddar cheese was determined using the retronasal aroma simulator (RAS). Seven odor potent fatty acids identified in Cheddar cheese were placed in model systems and sampled in the RAS. Volatile acids were trapped by solid phase microextraction and identified by GC/MS. The six released fatty acids were added to a model cheese system and subjected to a descriptive analysis sensory test, using omission testing (N-1). Six cheese models, each omitting one fatty acid, were tested in triplicate against a complete model by a trained panel, under a randomized complete block design. Panelists rated the intensity of six descriptors. In one additional test session, the complete model was tested against a model omitting all fatty acids. Results indicated that the omission of propionic acid from the cheese model led to a significant increase (a=0.10) in the ratings for the 'cream' descriptor (P=0.08). The omission of all fatty acids resulted in a significant decrease in the ratings for the 'sweaty' descriptor (P=0.07). Surprisingly, the ratings for the 'Cheddar' descriptor did not change under any circumstances. This suggests that although some compounds contribute heavily to the aroma of a food based on their odor potency, the removal of such compounds does not necessarily alter the sensory perception of the overall food concept.
Diacetyl, an important wine flavorant synthesized during alcoholic and malolactic fermentation, h... more Diacetyl, an important wine flavorant synthesized during alcoholic and malolactic fermentation, has been reported to have a sensory threshold of 2-3 mg/l. A comparative study of threshold for diacetyl in wines was undertaken to determine the effect of wine type on that value. Sensory threshold was determined according to the forced-choice ascending concentration series of limits method described by ASTM (E 679-79), using trained panelists. Panel detection thresholds and standard deviation from the geometric mean were found to be 0.2 mg/l and 0.32 in Chardonnay, 0.9 rngfl and 0.21 in Pinot noir, and 2.8 mgfl and 0.38 in Cabernet Sauvignon. These results demonstrate the important effect of wine type on diacetyl threshold, invalidating the use of a single threshold value for all wines.
Growth of the yeast Brettanomyces/Dekkera in wine can drastically alter the aroma characteristics... more Growth of the yeast Brettanomyces/Dekkera in wine can drastically alter the aroma characteristics to the point where all varietal and regional flavor characteristics are overwhelmed by the flavors produced by these yeasts. To avoid spoilage it is important to know more about the aromas formed by these yeasts and be able to detect the changes in aroma early so that further growth of the yeast and further aroma modification can be avoided. Two groups of commercial wines with suspected "Brett" character were evaluated by two trained panels of judges. The first group included four Cabernet Sauvignon and two Pinot Noir wines; the second included four Cabernet Sauvignon wines. All were evaluated by sensory descriptive analysis and GC/MS 4-ethyl phenol analysis. Characteristic "Brett" aromas such as plastic, burnt plastic, Band-aid (TM), cow manure, barnyard, and horse sweat were summarized by the first group of tasters as 'plastic.' For the second group 'plastic' included only pastic, burnt plastic, and Band-aid (TM) odors. Dry manure and sweaty/animal were separate descriptors. In both groups, the wines were differentiated by univariate analysis of variance (ANOVA) and multivariate discriminant analysis (DA) by two descriptors: plastic and fruity. The greatest fruit character and lowest plastic scores defined the younger Cabernets, and the opposite was true for the older wines. There was little difference between the two Pinot Noirs for either descriptor. The a priori "Brett" observations from the winemakers proved to be a consistent predictor of Brett character for all wines. The observations also agreed with the 4-ethyl phenol concentrations and the post-hoc plastic mean scores from the ANOVA analyses. The "strong Brett" wines were the older vintage wines with higher 4-ethyl phenol concentrations, higher plastic and lower fruity mean scores. Wines with "maybe some" and "no Brett" had the lower 4-ethyl phenol concentrations and more fruit with less plastic scores. This investigation shows that aroma modifications by Brettanomyces yeasts can be reliably detected and quantified with trained tasters. Further investigations into the chemical basis of the 'Brett' aromas will allow us to use chemical indicators to detect activity of these yeasts early.
The Brettanomyces / Dekkera yeasts can be found in fermenting must and in wine. Typically they gr... more The Brettanomyces / Dekkera yeasts can be found in fermenting must and in wine. Typically they grow after alcoholic and malolactic fermentation during storage of wine in tank, barrel, or bottle. They contribute characteristic bretty flavors which are described as smoky, barnyard, plastic, burnt plastic, vinyl, Bandaid, and creosote. They can also contribute a metallic bitterness. Compounds which are responsible for brett flavor in wine include 4-ethyl phenol, 4-ethyl guaiacol, isovaleric acid, and unidentified burnt plastic compound. Descriptive sensory evaluations show an inverse relationship between fruity and bretty flavor perception. The brett aromas in some wines are considered a positive attribute, especially when present at low concentration. Often these flavors are considered a defect. The wine's varietal and regional flavor characteristics might be completely masked by these flavors and the wine can be unpleasantly bitter. 4-ethyl phenol is used by some wineries as an indicator compound for the activity of Brettanomyces. Yet some wines having a strong brett flavors do contain none or very little 4-ethyl phenol. Preliminary studies show that 4-ethyl phenol is formed all through growth of Brettanomyces. Thus this compound can be used to confirm the presence of bretty flavors. The search for indicator compounds formed during early stages of growth of B. continues. The Brettanomyces yeasts can produce the characteristic brett flavors when growing at low cell density of several hundred to several thousand cells per mL. The fact that these yeasts are often present at low cell numbers and that they are slow growing makes detection difficult. Genetic analyses of wine isolates have shown that only strains of B. bruxellensis grow in wine. Semi-selective plating is performed prior to genetic analysis on media including cycloheximide. The development of DNA based probes has made it possible to reliably identify the yeast once it is plated on a nutrient agar plate. Further developments of specific probes and of probe application techniques will improve the specificity and speed of detection.
In presenting the material in this chapter, four fundamental propositions are made. These are: (1... more In presenting the material in this chapter, four fundamental propositions are made. These are: (1) Sucrose (sugar) tastes sweet. (2) Quinine tastes bitter. (3) Sodium chloride tastes salty 1. (4) Hydrochloric acid tastes sour.
... IN RELATION TO PROCESSING AND VARIETY CY Lee, WB Robinson, JP Van Buren, TE Acree, and GS Sto... more ... IN RELATION TO PROCESSING AND VARIETY CY Lee, WB Robinson, JP Van Buren, TE Acree, and GS Stoewsand ... Wines prepared from the vinifera grapes 'Pinot noir' or 'Riesling' contained low amounts of methanol and were more uniform year to year. ... 'Vincent' 19 141 ...
Page 1. CONCORD WINE COMPOSITION AS AFFECTED AND PROCESSING TECHNIQUE BY MATURITY Richard R. Nels... more Page 1. CONCORD WINE COMPOSITION AS AFFECTED AND PROCESSING TECHNIQUE BY MATURITY Richard R. Nelson and Terry E. Acree Respectively Graduate Research Assistant and Associate Professor of Biochemistry ...
... IN RELATION TO PROCESSING AND VARIETY CY Lee, WB Robinson, JP Van Buren, TE Acree, and GS Sto... more ... IN RELATION TO PROCESSING AND VARIETY CY Lee, WB Robinson, JP Van Buren, TE Acree, and GS Stoewsand ... Wines prepared from the vinifera grapes 'Pinot noir' or 'Riesling' contained low amounts of methanol and were more uniform year to year. ... 'Vincent' 19 141 ...
Diacetyl, a flavor compound having a distinct buttery character, accumulates during alcoholic and... more Diacetyl, a flavor compound having a distinct buttery character, accumulates during alcoholic and malolactic fermentation (MLF) of wine. In an effort to investigate the occurrence of this compound in US Chardonnay wines, 41 wines from 36 wineries were analyzed for their diacetyl ...
Masking unpleasant odors with high levels of pleasant-smelling odorants is an ancient practice th... more Masking unpleasant odors with high levels of pleasant-smelling odorants is an ancient practice that has evolved into many enterprises, from perfumery to consumer products. However, effective odor masking turns out to be idiosyncratic and impermanent. Here, we used Sniff Olfactometry (SO)(Rochelle et al., 2017; Wyckoff & Acree, 2017) to investigate the psychophysics of masking during 70ms-stimulations with mixtures of the mal-odorantiso-valeric Acid (IVA) and different masking agents. IVA is a component of human sweat that can dominate its smell, and is often described in unpleasant terms, e.g., “gym locker”, “smelly feet”, “dirty clothes”, etc. Conventionally, high concentrations of positive smelling odorants are used to reduce the unpleasantness of IVA in clothing or environments contaminated with IVA. To investigate the masking effects of sub-threshold levels of masking agents (neohivernal, geraniol, florhydral, decanal,iso-longifolanone, methyliso-eugenol, ands-limonene) on IVA, ...
Research Note Incubation of plant material with potassium metabisulfite was found to inhibit fung... more Research Note Incubation of plant material with potassium metabisulfite was found to inhibit fungal infections of explants from grapevines. Grapevine tissue of Vitis labruscana cv. Concord was incubated with sulfite pads containing 0.4 g of potassium metabilsufite for one and two days prior to culturing and evaluated against a control that had been surface sterilized with 0.5 % NaOCI and 70 % ethanol after one week for losses due to microbial contamination. Sulfite fumigation of plant material reduced the incidence of mold infection, particularly in tissue cultures developed from fruit explants which had reductions in contamination as high as 10 fold. Continued attempts to isolate contaminants from cultures intitiated from these explants showed no signs of infection.
Growth of the yeast Brettanomyces/Dekkera in wine can drastically alter the aroma characteristics... more Growth of the yeast Brettanomyces/Dekkera in wine can drastically alter the aroma characteristics to the point where all varietal and regional flavor characteristics are overwhelmed by the flavors produced by these yeasts. To avoid spoilage it is important to know more about the aromas formed by these yeasts and be able to detect the changes in aroma early so that further growth of the yeast and further aroma modification can be avoided. Two groups of commercial wines with suspected "Brett" character were evaluated by two trained panels of judges. The first group included four Cabernet Sauvignon and two Pinot Noir wines; the second included four Cabernet Sauvignon wines. All were evaluated by sensory descriptive analysis and GC/MS 4-ethyl phenol analysis. Characteristic "Brett" aromas such as plastic, burnt plastic, Band-aid (TM), cow manure, barnyard, and horse sweat were summarized by the first group of tasters as 'plastic.' For the second group 'pl...
Red tart cherries, diced green bell peppers, and diced apple were dried in various ways with and ... more Red tart cherries, diced green bell peppers, and diced apple were dried in various ways with and without sulfite treatment. Drying alternatives inc uded short exposure to circulating hot air (air-drying), intermediate exposure at reduced temperature and pressure (vacuum-drying) and long exposure to high vacuum in the frozen state (freezedrying), Sulfite treatment of these materials waa accomplished by dipping in an aqueous solution of NaHS03 (1000-10,000 ppm) or by tumbling in a mixture of S0 2 (2-4%) in air. The dried products were hermetically packaged, in some cases under nitrogen or with desiccant, and stored for six months at-35 or +100°F, Product quality was then evaluated in terms of moisture, residual SO2, color, odor or flavor, and rehydration characteristics. The most important consideration in keeping quality was moisture content. In-package desiccation was required to reduce two-stage, air/vacuum-dried cherries or peppers to a moisture level, low enough (1-2%) that quality recna~ned acceptable in stora e at 100°Ej Sulfite treatment and packing under nitrogen were insufficient separately or together, to provide the necessary protection against browning reactions at higher moisture. And only a slight improvement in quality was noted in sulfited products dried to the lower moisture, in i.'ilch condition even untreated controls were usually just about acceptable. In-package desiccation was not sufficient to provide final drying for higher moisture products prepared only by air-drying and was mainly unnecessary for chose properly treeze-dried, (See continua'ion she O REPLACE« OO FORM l«TS. 1 JAN 14. WHICH If »%f% POftM * A "*J^ REPLACE« OO FORM l«TS. UU ,HOV»l47»5 O.tOLtT« FOR AHMT Ulf It' UNCLASSIFIED Security Ct«««ific«iior. I UNCLASSIFIED "Ucurity ClatilUcatLon 14. KEY WORD» LINK * kINW •
... Megazyme Total Starch Assay (Amyloglucosidase/a-Amylase Method) Alternate Protocol: Enzymatic... more ... Megazyme Total Starch Assay (Amyloglucosidase/a-Amylase Method) Alternate Protocol: Enzymatic Quantitation of Total Starch (Holm Method) Reagents ... Acree, Eric A. Decker, Michael H. Penner, David S. Reid, Steven J. Schwartz, Charles F. Shoemaker, Denise Smith, Peter ...
Proteins are the servants of life. They occur in all component parts of living organisms and are ... more Proteins are the servants of life. They occur in all component parts of living organisms and are staggering in their functional variety, despite their chemical similarity. Even the simplest single-cell organism contains a thousand different proteins, fulfilling a wide range of life-supporting roles. Their production is controlled by the cell's genetic machinery, and a malfunction of even one protein in the cell will give rise to pathological symptoms. Additions to the total number of known proteins are constantly being made on an increasing scale through the discovery of mutant strains or their production by genetic manipulation; this latter technology has become known as protein engineering. The in vivo functioning of proteins depends critically on the chemical structure of individual peptide chains, but also on the detailed folding of the chains themselves and on their assembly into larger supramolecular structures. The molecules and their functional assemblies possess a limited in vitro stability. Special methods are required for their intact isolation from the source material and for their analysis, both qualitatively and quantitatively. Proteins are also increasingly used as "industrial components," e.g., in biosensors and immobilized enzymes, because of their specificity, selectivity, and sensitivity. This requires novel and refined processing methods by which the protein isolate can be converted into a form in which it can be utilized. This book provides a unified approach to several essential aspects of protein technology: classifications of protein function, both in situ and in the form of isolates, criteria that govern in vitro protein stability limits, methods of detection, isolation and separation from nanogram to tonne quantities, analysis in situ and in the isolated state, and the technology of protein processing for the production of stable preparations for clinical, agricultural, or industrial use. This book is based on material initially prepared for several postexperience courses: "Characterization of Proteins-Their Analysis and Isolation," taught by the authors on behalf of the Center for Professional Advancement in the US and Europe. It is intended for academic, medical, and a wide range of industrial vi Preface research and development scientists who are actively involved in protein isolation, purification, characterization, and the setting and measuring of protein standards of performance. A general survey of the chemical and functional properties of proteins and the economics of protein isolation and processing is followed by a survey of the parameters that circumscribe protein stability in vitro. The next section deals with in vivo characterization, detection, and localization of several important groups of proteins (e.g., peptide hormones and receptors). This is followed by several chapters describing chromatographic, electrophoretic, and immunological methods employed in the analytical and preparative scale separation, isolation, and characterization of proteinaceous materials, from amino acids through peptide fragments and intact proteins. The final section is devoted to aspects of large-scale processing and quality control methods. This volume differs from most monographs on proteins in that it treats these molecules as valuable but labile chemical raw materials that are easily inactivated by conventional processing techniques. Assuming some previous knowledge of protein analytical, physical, and biochemistry, the book combines these disci P lines to produce a synthesis of the parameters that are essential or the successful isolation, separation, characterization, and stabilization of proteins.
SUMMARY —The conversion of glutamine to the bitter compound, 2‐pyrrolidone‐5‐carboxylic acid (PCA... more SUMMARY —The conversion of glutamine to the bitter compound, 2‐pyrrolidone‐5‐carboxylic acid (PCA), in table beets was studied. Glutamine was analyzed by a phosphate‐buffer hydrolysis and distillation method. PCA was extracted with ethyl acetate and the ditrimethylsilyl derivative prepared and measured quantitatively by gas‐liquid chromatography. The accumulation of glutamine in fresh beets with excessive amounts of nitrogen fertilization caused a substantial increase in PCA content of processed beets. Conversion of glutamine to PCA in beets was proportional to the heating time during processing. Glutamine content did not alter during raw beet storage periods at 35°F; PCA content increased gradually.
Proteins are the servants of life. They occur in all component parts of living organisms and are ... more Proteins are the servants of life. They occur in all component parts of living organisms and are staggering in their functional variety, despite their chemical similarity. Even the simplest single-cell organism contains a thousand different proteins, fulfilling a wide range of life-supporting roles. Their production is controlled by the cell's genetic machinery, and a malfunction of even one protein in the cell will give rise to pathological symptoms. Additions to the total number of known proteins are constantly being made on an increasing scale through the discovery of mutant strains or their production by genetic manipulation; this latter technology has become known as protein engineering. The in vivo functioning of proteins depends critically on the chemical structure of individual peptide chains, but also on the detailed folding of the chains themselves and on their assembly into larger supramolecular structures. The molecules and their functional assemblies possess a limited in vitro stability. Special methods are required for their intact isolation from the source material and for their analysis, both qualitatively and quantitatively. Proteins are also increasingly used as "industrial components," e.g., in biosensors and immobilized enzymes, because of their specificity, selectivity, and sensitivity. This requires novel and refined processing methods by which the protein isolate can be converted into a form in which it can be utilized. This book provides a unified approach to several essential aspects of protein technology: classifications of protein function, both in situ and in the form of isolates, criteria that govern in vitro protein stability limits, methods of detection, isolation and separation from nanogram to tonne quantities, analysis in situ and in the isolated state, and the technology of protein processing for the production of stable preparations for clinical, agricultural, or industrial use. This book is based on material initially prepared for several postexperience courses: "Characterization of Proteins-Their Analysis and Isolation," taught by the authors on behalf of the Center for Professional Advancement in the US and Europe. It is intended for academic, medical, and a wide range of industrial vi Preface research and development scientists who are actively involved in protein isolation, purification, characterization, and the setting and measuring of protein standards of performance. A general survey of the chemical and functional properties of proteins and the economics of protein isolation and processing is followed by a survey of the parameters that circumscribe protein stability in vitro. The next section deals with in vivo characterization, detection, and localization of several important groups of proteins (e.g., peptide hormones and receptors). This is followed by several chapters describing chromatographic, electrophoretic, and immunological methods employed in the analytical and preparative scale separation, isolation, and characterization of proteinaceous materials, from amino acids through peptide fragments and intact proteins. The final section is devoted to aspects of large-scale processing and quality control methods. This volume differs from most monographs on proteins in that it treats these molecules as valuable but labile chemical raw materials that are easily inactivated by conventional processing techniques. Assuming some previous knowledge of protein analytical, physical, and biochemistry, the book combines these disci P lines to produce a synthesis of the parameters that are essential or the successful isolation, separation, characterization, and stabilization of proteins.
The fatty acid profile from the retronasal aroma of Cheddar cheese was determined using the retro... more The fatty acid profile from the retronasal aroma of Cheddar cheese was determined using the retronasal aroma simulator (RAS). Seven odor potent fatty acids identified in Cheddar cheese were placed in model systems and sampled in the RAS. Volatile acids were trapped by solid phase microextraction and identified by GC/MS. The six released fatty acids were added to a model cheese system and subjected to a descriptive analysis sensory test, using omission testing (N-1). Six cheese models, each omitting one fatty acid, were tested in triplicate against a complete model by a trained panel, under a randomized complete block design. Panelists rated the intensity of six descriptors. In one additional test session, the complete model was tested against a model omitting all fatty acids. Results indicated that the omission of propionic acid from the cheese model led to a significant increase (a=0.10) in the ratings for the 'cream' descriptor (P=0.08). The omission of all fatty acids resulted in a significant decrease in the ratings for the 'sweaty' descriptor (P=0.07). Surprisingly, the ratings for the 'Cheddar' descriptor did not change under any circumstances. This suggests that although some compounds contribute heavily to the aroma of a food based on their odor potency, the removal of such compounds does not necessarily alter the sensory perception of the overall food concept.
Diacetyl, an important wine flavorant synthesized during alcoholic and malolactic fermentation, h... more Diacetyl, an important wine flavorant synthesized during alcoholic and malolactic fermentation, has been reported to have a sensory threshold of 2-3 mg/l. A comparative study of threshold for diacetyl in wines was undertaken to determine the effect of wine type on that value. Sensory threshold was determined according to the forced-choice ascending concentration series of limits method described by ASTM (E 679-79), using trained panelists. Panel detection thresholds and standard deviation from the geometric mean were found to be 0.2 mg/l and 0.32 in Chardonnay, 0.9 rngfl and 0.21 in Pinot noir, and 2.8 mgfl and 0.38 in Cabernet Sauvignon. These results demonstrate the important effect of wine type on diacetyl threshold, invalidating the use of a single threshold value for all wines.
Growth of the yeast Brettanomyces/Dekkera in wine can drastically alter the aroma characteristics... more Growth of the yeast Brettanomyces/Dekkera in wine can drastically alter the aroma characteristics to the point where all varietal and regional flavor characteristics are overwhelmed by the flavors produced by these yeasts. To avoid spoilage it is important to know more about the aromas formed by these yeasts and be able to detect the changes in aroma early so that further growth of the yeast and further aroma modification can be avoided. Two groups of commercial wines with suspected "Brett" character were evaluated by two trained panels of judges. The first group included four Cabernet Sauvignon and two Pinot Noir wines; the second included four Cabernet Sauvignon wines. All were evaluated by sensory descriptive analysis and GC/MS 4-ethyl phenol analysis. Characteristic "Brett" aromas such as plastic, burnt plastic, Band-aid (TM), cow manure, barnyard, and horse sweat were summarized by the first group of tasters as 'plastic.' For the second group 'plastic' included only pastic, burnt plastic, and Band-aid (TM) odors. Dry manure and sweaty/animal were separate descriptors. In both groups, the wines were differentiated by univariate analysis of variance (ANOVA) and multivariate discriminant analysis (DA) by two descriptors: plastic and fruity. The greatest fruit character and lowest plastic scores defined the younger Cabernets, and the opposite was true for the older wines. There was little difference between the two Pinot Noirs for either descriptor. The a priori "Brett" observations from the winemakers proved to be a consistent predictor of Brett character for all wines. The observations also agreed with the 4-ethyl phenol concentrations and the post-hoc plastic mean scores from the ANOVA analyses. The "strong Brett" wines were the older vintage wines with higher 4-ethyl phenol concentrations, higher plastic and lower fruity mean scores. Wines with "maybe some" and "no Brett" had the lower 4-ethyl phenol concentrations and more fruit with less plastic scores. This investigation shows that aroma modifications by Brettanomyces yeasts can be reliably detected and quantified with trained tasters. Further investigations into the chemical basis of the 'Brett' aromas will allow us to use chemical indicators to detect activity of these yeasts early.
The Brettanomyces / Dekkera yeasts can be found in fermenting must and in wine. Typically they gr... more The Brettanomyces / Dekkera yeasts can be found in fermenting must and in wine. Typically they grow after alcoholic and malolactic fermentation during storage of wine in tank, barrel, or bottle. They contribute characteristic bretty flavors which are described as smoky, barnyard, plastic, burnt plastic, vinyl, Bandaid, and creosote. They can also contribute a metallic bitterness. Compounds which are responsible for brett flavor in wine include 4-ethyl phenol, 4-ethyl guaiacol, isovaleric acid, and unidentified burnt plastic compound. Descriptive sensory evaluations show an inverse relationship between fruity and bretty flavor perception. The brett aromas in some wines are considered a positive attribute, especially when present at low concentration. Often these flavors are considered a defect. The wine's varietal and regional flavor characteristics might be completely masked by these flavors and the wine can be unpleasantly bitter. 4-ethyl phenol is used by some wineries as an indicator compound for the activity of Brettanomyces. Yet some wines having a strong brett flavors do contain none or very little 4-ethyl phenol. Preliminary studies show that 4-ethyl phenol is formed all through growth of Brettanomyces. Thus this compound can be used to confirm the presence of bretty flavors. The search for indicator compounds formed during early stages of growth of B. continues. The Brettanomyces yeasts can produce the characteristic brett flavors when growing at low cell density of several hundred to several thousand cells per mL. The fact that these yeasts are often present at low cell numbers and that they are slow growing makes detection difficult. Genetic analyses of wine isolates have shown that only strains of B. bruxellensis grow in wine. Semi-selective plating is performed prior to genetic analysis on media including cycloheximide. The development of DNA based probes has made it possible to reliably identify the yeast once it is plated on a nutrient agar plate. Further developments of specific probes and of probe application techniques will improve the specificity and speed of detection.
In presenting the material in this chapter, four fundamental propositions are made. These are: (1... more In presenting the material in this chapter, four fundamental propositions are made. These are: (1) Sucrose (sugar) tastes sweet. (2) Quinine tastes bitter. (3) Sodium chloride tastes salty 1. (4) Hydrochloric acid tastes sour.
... IN RELATION TO PROCESSING AND VARIETY CY Lee, WB Robinson, JP Van Buren, TE Acree, and GS Sto... more ... IN RELATION TO PROCESSING AND VARIETY CY Lee, WB Robinson, JP Van Buren, TE Acree, and GS Stoewsand ... Wines prepared from the vinifera grapes 'Pinot noir' or 'Riesling' contained low amounts of methanol and were more uniform year to year. ... 'Vincent' 19 141 ...
Page 1. CONCORD WINE COMPOSITION AS AFFECTED AND PROCESSING TECHNIQUE BY MATURITY Richard R. Nels... more Page 1. CONCORD WINE COMPOSITION AS AFFECTED AND PROCESSING TECHNIQUE BY MATURITY Richard R. Nelson and Terry E. Acree Respectively Graduate Research Assistant and Associate Professor of Biochemistry ...
... IN RELATION TO PROCESSING AND VARIETY CY Lee, WB Robinson, JP Van Buren, TE Acree, and GS Sto... more ... IN RELATION TO PROCESSING AND VARIETY CY Lee, WB Robinson, JP Van Buren, TE Acree, and GS Stoewsand ... Wines prepared from the vinifera grapes 'Pinot noir' or 'Riesling' contained low amounts of methanol and were more uniform year to year. ... 'Vincent' 19 141 ...
Diacetyl, a flavor compound having a distinct buttery character, accumulates during alcoholic and... more Diacetyl, a flavor compound having a distinct buttery character, accumulates during alcoholic and malolactic fermentation (MLF) of wine. In an effort to investigate the occurrence of this compound in US Chardonnay wines, 41 wines from 36 wineries were analyzed for their diacetyl ...
Masking unpleasant odors with high levels of pleasant-smelling odorants is an ancient practice th... more Masking unpleasant odors with high levels of pleasant-smelling odorants is an ancient practice that has evolved into many enterprises, from perfumery to consumer products. However, effective odor masking turns out to be idiosyncratic and impermanent. Here, we used Sniff Olfactometry (SO)(Rochelle et al., 2017; Wyckoff & Acree, 2017) to investigate the psychophysics of masking during 70ms-stimulations with mixtures of the mal-odorantiso-valeric Acid (IVA) and different masking agents. IVA is a component of human sweat that can dominate its smell, and is often described in unpleasant terms, e.g., “gym locker”, “smelly feet”, “dirty clothes”, etc. Conventionally, high concentrations of positive smelling odorants are used to reduce the unpleasantness of IVA in clothing or environments contaminated with IVA. To investigate the masking effects of sub-threshold levels of masking agents (neohivernal, geraniol, florhydral, decanal,iso-longifolanone, methyliso-eugenol, ands-limonene) on IVA, ...
Research Note Incubation of plant material with potassium metabisulfite was found to inhibit fung... more Research Note Incubation of plant material with potassium metabisulfite was found to inhibit fungal infections of explants from grapevines. Grapevine tissue of Vitis labruscana cv. Concord was incubated with sulfite pads containing 0.4 g of potassium metabilsufite for one and two days prior to culturing and evaluated against a control that had been surface sterilized with 0.5 % NaOCI and 70 % ethanol after one week for losses due to microbial contamination. Sulfite fumigation of plant material reduced the incidence of mold infection, particularly in tissue cultures developed from fruit explants which had reductions in contamination as high as 10 fold. Continued attempts to isolate contaminants from cultures intitiated from these explants showed no signs of infection.
Growth of the yeast Brettanomyces/Dekkera in wine can drastically alter the aroma characteristics... more Growth of the yeast Brettanomyces/Dekkera in wine can drastically alter the aroma characteristics to the point where all varietal and regional flavor characteristics are overwhelmed by the flavors produced by these yeasts. To avoid spoilage it is important to know more about the aromas formed by these yeasts and be able to detect the changes in aroma early so that further growth of the yeast and further aroma modification can be avoided. Two groups of commercial wines with suspected "Brett" character were evaluated by two trained panels of judges. The first group included four Cabernet Sauvignon and two Pinot Noir wines; the second included four Cabernet Sauvignon wines. All were evaluated by sensory descriptive analysis and GC/MS 4-ethyl phenol analysis. Characteristic "Brett" aromas such as plastic, burnt plastic, Band-aid (TM), cow manure, barnyard, and horse sweat were summarized by the first group of tasters as 'plastic.' For the second group 'pl...
Red tart cherries, diced green bell peppers, and diced apple were dried in various ways with and ... more Red tart cherries, diced green bell peppers, and diced apple were dried in various ways with and without sulfite treatment. Drying alternatives inc uded short exposure to circulating hot air (air-drying), intermediate exposure at reduced temperature and pressure (vacuum-drying) and long exposure to high vacuum in the frozen state (freezedrying), Sulfite treatment of these materials waa accomplished by dipping in an aqueous solution of NaHS03 (1000-10,000 ppm) or by tumbling in a mixture of S0 2 (2-4%) in air. The dried products were hermetically packaged, in some cases under nitrogen or with desiccant, and stored for six months at-35 or +100°F, Product quality was then evaluated in terms of moisture, residual SO2, color, odor or flavor, and rehydration characteristics. The most important consideration in keeping quality was moisture content. In-package desiccation was required to reduce two-stage, air/vacuum-dried cherries or peppers to a moisture level, low enough (1-2%) that quality recna~ned acceptable in stora e at 100°Ej Sulfite treatment and packing under nitrogen were insufficient separately or together, to provide the necessary protection against browning reactions at higher moisture. And only a slight improvement in quality was noted in sulfited products dried to the lower moisture, in i.'ilch condition even untreated controls were usually just about acceptable. In-package desiccation was not sufficient to provide final drying for higher moisture products prepared only by air-drying and was mainly unnecessary for chose properly treeze-dried, (See continua'ion she O REPLACE« OO FORM l«TS. 1 JAN 14. WHICH If »%f% POftM * A "*J^ REPLACE« OO FORM l«TS. UU ,HOV»l47»5 O.tOLtT« FOR AHMT Ulf It' UNCLASSIFIED Security Ct«««ific«iior. I UNCLASSIFIED "Ucurity ClatilUcatLon 14. KEY WORD» LINK * kINW •
... Megazyme Total Starch Assay (Amyloglucosidase/a-Amylase Method) Alternate Protocol: Enzymatic... more ... Megazyme Total Starch Assay (Amyloglucosidase/a-Amylase Method) Alternate Protocol: Enzymatic Quantitation of Total Starch (Holm Method) Reagents ... Acree, Eric A. Decker, Michael H. Penner, David S. Reid, Steven J. Schwartz, Charles F. Shoemaker, Denise Smith, Peter ...
Proteins are the servants of life. They occur in all component parts of living organisms and are ... more Proteins are the servants of life. They occur in all component parts of living organisms and are staggering in their functional variety, despite their chemical similarity. Even the simplest single-cell organism contains a thousand different proteins, fulfilling a wide range of life-supporting roles. Their production is controlled by the cell's genetic machinery, and a malfunction of even one protein in the cell will give rise to pathological symptoms. Additions to the total number of known proteins are constantly being made on an increasing scale through the discovery of mutant strains or their production by genetic manipulation; this latter technology has become known as protein engineering. The in vivo functioning of proteins depends critically on the chemical structure of individual peptide chains, but also on the detailed folding of the chains themselves and on their assembly into larger supramolecular structures. The molecules and their functional assemblies possess a limited in vitro stability. Special methods are required for their intact isolation from the source material and for their analysis, both qualitatively and quantitatively. Proteins are also increasingly used as "industrial components," e.g., in biosensors and immobilized enzymes, because of their specificity, selectivity, and sensitivity. This requires novel and refined processing methods by which the protein isolate can be converted into a form in which it can be utilized. This book provides a unified approach to several essential aspects of protein technology: classifications of protein function, both in situ and in the form of isolates, criteria that govern in vitro protein stability limits, methods of detection, isolation and separation from nanogram to tonne quantities, analysis in situ and in the isolated state, and the technology of protein processing for the production of stable preparations for clinical, agricultural, or industrial use. This book is based on material initially prepared for several postexperience courses: "Characterization of Proteins-Their Analysis and Isolation," taught by the authors on behalf of the Center for Professional Advancement in the US and Europe. It is intended for academic, medical, and a wide range of industrial vi Preface research and development scientists who are actively involved in protein isolation, purification, characterization, and the setting and measuring of protein standards of performance. A general survey of the chemical and functional properties of proteins and the economics of protein isolation and processing is followed by a survey of the parameters that circumscribe protein stability in vitro. The next section deals with in vivo characterization, detection, and localization of several important groups of proteins (e.g., peptide hormones and receptors). This is followed by several chapters describing chromatographic, electrophoretic, and immunological methods employed in the analytical and preparative scale separation, isolation, and characterization of proteinaceous materials, from amino acids through peptide fragments and intact proteins. The final section is devoted to aspects of large-scale processing and quality control methods. This volume differs from most monographs on proteins in that it treats these molecules as valuable but labile chemical raw materials that are easily inactivated by conventional processing techniques. Assuming some previous knowledge of protein analytical, physical, and biochemistry, the book combines these disci P lines to produce a synthesis of the parameters that are essential or the successful isolation, separation, characterization, and stabilization of proteins.
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