Leo McCloskey

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Leo McCloskey co-authored algorithms which explain the traditional European classification (e.g. A.O.C and 1855 Classification) of wines, which were used to create the California luxury wine industry in the Napa Valley, California, U.S.. At the center of the algorithm is a mathematical model of a wine market containing quality measures of style, quality and aging potential (freshness). From the model one can deduce a formula, which gives a theoretical estimate of quality score recorded in the MAX- Preference Scorecard, U.S. wine critics' 100-point scores and business performance. The formula led to scaling wines' ratings, price and volume in the Napa Valley, California, U.S., and legitimized scientifically the consumer 100-point scores in USA and producer classification in France. The Arrhenius- McCloskey-Sylvan model for Terroir is published by American Chemical Society journal in 1995. McCloskey's models are now proprietary and Enologix’s products and software sold in California, U.S.

Leo McCloskey's qualifications are experience in agribusiness and high-technology with Doctor of Philosophy at University of California, Santa Cruz, Chemical Ecology. 1984 which he used to create the algorithms which are the products of Enologix, Inc., Sonoma, California, USA. Prior to this he was president of a wine company.
Address: Sonoma, California, United States

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Papers by Leo McCloskey

An Enzymatic Assay for Acetaldehyde in Grape Juice and Wine

American Journal of Enology and Viticulture, 1981

A rapid enzymatic method for the determination of acetaldehyde in juice and wine is presented. Th... more A rapid enzymatic method for the determination of acetaldehyde in juice and wine is presented. The assay measures both acetaldehyde and the bisulfite addition product, l-hydroxyethane sulfonic acid. The assay utilizes one enzyme and NADH. This assay essentially recovers 100% of the acetaldehyde and the statistical data are good. The standard deviation was less than 1 ppm at a mean of 120 ppm. The assay was applied to both red and white wines and any interferences due to red wine phenolics was overcome with PVP. When applied to table wines, the assay showed an average of 83 ppm for reds and 32 ppm for whites.

Analysis of Anthocyanins in<i>Vitis Vinifera</i>Wines and Red Color Versus Aging by HPLC and Spectrophotometry

American Journal of Enology and Viticulture, 1981

Chemical Markers for Aroma of Vitis vinifera Var. Chardonnay Regional Wines

Journal of Agricultural and Food Chemistry, 1996

Since objective measures of appellations are needed for wine, California Vitis vinifera Var. Char... more Since objective measures of appellations are needed for wine, California Vitis vinifera Var. Chardonnay wines (n) 48) were surveyed for several aroma compounds including esters, norisoprenoids, and terpenes. For the first time concentrations of volatile fragrances were directly correlated with descriptive analysis scores that statistical analysis of the sensory data showed were associated with regional uniqueness and distinctness. Sensory scores for 10 terms used by industry quality experts to describe wines from four regions were compared to the concentrations of over 30 wine chemical compounds. Frequency of use of individual grape-based aroma terms were significantly correlated (p < 0.05) with linalool, 1,1,6-trimethyldihydronaphthalene, 3-methylbutyl acetate, ethyl 2-hydroxypropanoate, and 2-phenylethanol. Linalool concentrations were also correlated with R-terpineol. Also, 4-terpineol, geraniol, nerol, and linalool oxide (furan) were found in Chardonnay wines from all of the regions of California.

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Analysis of Anthocyanins in Vitis Vinifera Wines and Red Color Versus Aging by HPLC and Spectrophotometry

American Journal of Enology and Viticulture, 1981

The red color of wines made from Vitis vinifera grapes in ten consecutive years between 1970 and ... more The red color of wines made from Vitis vinifera grapes in ten consecutive years between 1970 and 1979 was studied by measuring the anthocyanins. The anthocyanins were measured in Zinfandel and Cabernet Sauvignon using HPLC and spectrophotometry on newly fermented to very old wine. Also, anthocyanins were measured for three years in wines from the 1977 vintage. Information on Zinfandel anthocyanin composition is presented for the first time. Results show that anthocyanins are important in color for at least three years after fermentation and they continue to be present for up to five years. After 10 years of aging the anthocyanin levels are a few percent of new wine levels. The cinnamic acid acylated pigments disappear faster than the acetic acid acylated pigments. For unknown reasons it was also found that anthocyanin loss may be halted in some wines showing that they do not disappear linearly with time.

Enzymic assay for acetate ion

Biodynamically and Organically Managed Vineyards – 367 Soil and Winegrape Quality in Biodynamically and Organically Managed Vineyards

American Journal of Enology and Viticulture

367 Prior to the organic agricultural movement, biodynamic agriculture was developed in the 1920s... more 367 Prior to the organic agricultural movement, biodynamic agriculture was developed in the 1920s in response to concerns from farmers about the deteriorating soils and health of their farms (Steiner 1993). Similar to organic agri-culture, biodynamics eliminates synthetic chemical fertiliz-ers and pesticides. Biodynamics is a holistic approach that emphasizes soil building and high diversity of crops, animals, and wildlife habitat (Koepf et al. 1990); therefore, inputs from outside the farm are minimized and use of on-farm resources is optimized. In addition, biodynamic prac-titioners use a series of fermented manure, plant, and min-eral-based preparations on soil, crops, and compost (Table 1). These substances are not claimed to act as fertilizers but are said to stimulate soil nutrient cycling and promote photosynthesis and optimal compost development (Koepf et al. 1990). Organic and biodynamic farming practices are increasing worldwide. As of 2002, 1.5% of U.S. grape acreage was ...

Enzymatic Assay for Malic Acid and Malo-Lactic Fermentations

South African Journal for Enology and Viticulture

A rapid enzymatic method for the determination of malic acid in grape juice and wine is presented... more A rapid enzymatic method for the determination of malic acid in grape juice and wine is presented which is designed for monitoring malo-lactic fermentations in the said liquids. The results allow for the calculation of malate levels and therefore of malo-lactic fermentation rates. This particular enzymic assay for malic acid uses malate dehydrogenase and glutamate oxaloacetate transaminase for accelerating the main enzymic assay reaction catalyzed by malate dehydrogenase. The assay reactions utilize the photometric determination of NADH at 340 nm. In five minutes the analyst can detect up to 2000 mg/L malate and in seven minutes up to 4000 mg/L. Essentially 100% of the malic acid is recovered with a standard deviation of better than 35 ppm.

Gluconic Acid in California Wines

American Journal of Enology and Viticulture

Seventy red and white California table wines, produced primarily by Northern California wineries,... more Seventy red and white California table wines, produced primarily by Northern California wineries, were assayed for gluconic acid by an enzymatic procedure. The levels of gluconate ranged from none to 3.09 g/L, averaging 0.21 g/L for reds and 0.24 g/L for the whites. Eight white Bordeaux wines, labeled `Sauternes,' also assayed for gluconic acid, contained 1.28-5.89 g/L. Preliminary evidence suggests that gluconate was present in the assayed wines as a result of mold metabolism prior to vinification.

A New Enzymatic Assay for Glucose and Fructose

American Journal of Enology and Viticulture

Description d'une technique enzymatique rapide utilisant l'hexokinase, la phosphoglucose ... more Description d'une technique enzymatique rapide utilisant l'hexokinase, la phosphoglucose isomerase et la glucose-6-phosphate deshydrogenase pour le dosage des sucres reducteurs dans les vins et les jus. Les vins rouges, riches en tannins sont prealablement traites par la polyvinylpyrrolidone

Enzymatic Analysis for Glucose and Fructose

American Journal of Enology and Viticulture

United States Patent 4035239

An improved enzymic assay and assay composition for acetate ion in a biological fluid (e.g., bloo... more An improved enzymic assay and assay composition for acetate ion in a biological fluid (e.g., blood serum or tissue extract) or a solution of fruit juice origin (e.g., wine). The acetate ion is reacted with adenosine triphosphate in the presence of enzymic quantities of phosphotransacetylase to form adenosine diphosphate. The above procedure is accelerated by the presence of Coenzyme A and phosphotransacetylase enzyme during the formation of adenosine diphosphate. Thereafter, the quantity of adenosine diphosphate may be assayed by known enzymic techniques. The procedure may be employed for analysis of acetate esters (e.g., ethyl acetate) by hydrolysis to acetate ion in the presence of esterase.

An Improved Enzymic Assay for Acetate in Juice and Wine

American Journal of Enology and Viticulture

An enzymic method for determining acetic acid in grape juice and wine is described. A novel assay... more An enzymic method for determining acetic acid in grape juice and wine is described. A novel assay trapping reaction makes for faster assay times of 35 minutes by using an additional enzyme. The assay was also improved for red wine analysis by the use of gelatin and polyvinylpyrrolidone in the reagents to overcome phenolic interference. The assay yields results which show that the assay reactions are complete and this makes for a quantitative assay for acetate anion in wine and juice. The recovery of the acetic acid is essentially 100%. The assay presented has received official first action status for an AOAC procedure.

An Acetic Acid Assay for Wine Using Enzymes

American Journal of Enology and Viticulture

An enzymic method for determining acetic acid in grape juices and wines is described. The assay u... more An enzymic method for determining acetic acid in grape juices and wines is described. The assay uses the enzyme acetate kinase and coupled enzyme reactions to give a change in absorbance at 340 nm for the spectrophotometric determination of acetic acid. The method offers the advantages of a very precise analytical technique with a standard deviation of 0.73 mg/100 ml at 40 mg/100 ml acetic acid in wine. The recovery of acetic acid is essentially 100%. One operator can perform up to 300 assays manually per day with ease.

Will Napa Cabernet Become a Commodity?

As the clock ticks, Napa Valley’s Cabernet Sauvignon wines will become increasingly susceptible t... more As the clock ticks, Napa Valley’s Cabernet Sauvignon wines will become increasingly susceptible to commoditization. A commodity is a product for which there is demand, but it is bought and sold without qualitative differentiation. Napa Cabernet Sauvignon is to California wine what Yosemite is to our national parks. The Oakville district alone produces more cases of 90-plus point wines than any other Cabernet Sauvignon region in the New World. It is something of a state treasure that begs to be preserved. Napa’s Chardonnay and Cabernet Sauvignon wines were immortalized in the historic Judgment of Paris wine tasting in 1976. After that well-publicized event, many people thought that Napa Valley was “Burgundy in America.” They were mistaken. Though Napa was evolving to a luxury Chardonnay producer, it was an undifferentiated one that became a New World commodity. Diffusion of intellectual property such as rootstocks, scion wood and techniques from Napa led to plantings across Californi...

An enzymic assay for acetate fruit juices and wines

Journal of Agricultural and Food Chemistry, 1976

Evaluation of an Enzymatic Method for Estimating Ethanol in Wines Using an" Enzyme Kit

American Journal of Enology …, 1974

EVALUATION OF AN ENZYMATIC METHOD ESTIMATING ETHANOL IN WINES USING AN "ENZYME KIT'&quo... more

Adams-Harbertson Protein Precipitation-Based Wine Tannin Method Found Invalid

Journal of AOAC INTERNATIONAL, 2008

The poor precision of the Adams-Harbertson wine tannin assay which was proposed for commercial wi... more The poor precision of the Adams-Harbertson wine tannin assay which was proposed for commercial winemaking, thereby creating the real possibility of quality control problems, is documented. The method is a version of the Hagerman and Butler protein precipitation-based tannin method. An extensive invalidation of the assay results with luxury wine data shows that the assay cannot distinguish bottled wine with reasonable accuracy. Five laboratories used Adams-Harbertson to assay 9 replicates each, of 3 bottled wines (n 135) found in California supermarkets, with tannin concentrations of nominally 500 and 1000 ppm by high-performance liquid chromatography (HPLC). Reliability exceeded the 5 industry requirement by nominally 5 times (z-score based on 5 distribution). Coefficient of variation was 27, making the standard deviation range 54 for Pinot Noir, 34 for Merlot, and 44 for Cabernet Sauvignon. Validity exceeded the 100 requirement. Intralaboratory validity recovery was 5563. Interwine...

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Descriptive Analysis for Wine Quality Experts Determining Appellations by Chardonnay Wine Aroma

Journal of Sensory Studies, 1996

Since producer based sensory analysis of wine appellations remains in widespread use worldwide by... more Since producer based sensory analysis of wine appellations remains in widespread use worldwide by wineries, modem sensory methods were developed for industry judge panels. U. S. appellations were studied using modem sensory analysis processes which accommodated the industry professionals' biases for perceived quality and provincial sensory language. A panel was assembled comprised of wine industry quality experts (n = 26). First, judge quality biases were determined using a multi-wine preference-testing method (n = 48) in which judges freely record their aroma terms. Subsequently QDA@ type strategies were used to create the sensory language from analysis of 1100 wine x judge interactions in which free use of terms was used to describe the wines. Next, an experiment analyzed the wines using a new descriptive analysis scorecard which contained the ten most frequently used terms; and scores were computed from the number of times terms were selected by the judges Pequency of use). Groups of sixteen wines, for which the judges had no large negative bias, from the Cameros American Viticultural Areas (AVA), were compared to those from California wine growing regions (Central Coast, Napa and Sonoma). Replicate trials showed Cameros AVA and Central Coast wines clustered in the principal components

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Poor Interoperability of the Adams-Harbertson Method for Analysis of Anthocyanins: Comparison with AOAC pH Differential Method

Journal of AOAC International, 2013

The poor interoperability of anthocyanin glycosides measurements by two pH differential methods i... more The poor interoperability of anthocyanin glycosides measurements by two pH differential methods is documented. Adams-Harbertson, which was proposed for commercial winemaking, was compared to AOAC Official MethodSM 2005.02 for wine. California bottled wines (Pinot Noir, Merlot, and Cabernet Sauvignon) were assayed in a collaborative study (n = 105), which found mean precision of Adams- Harbertson winery versus reference measurements to be 77 ± 20%. Maximum error is expected to be 48% for Pinot Noir, 42% for Merlot, and 34% for Cabernet Sauvignon from reproducibility RSD. Range of measurements was actually 30 to 91% for Pinot Noir. An interoperability study (n = 30) found Adams-Harbertson produces measurements that are nominally 150% of the AOAC pH differential method. Large analytical chemistry differences are: AOAC method uses Beer-Lambert equation and measures absorbance at pH 1.0 and 4.5, proposed a priori by Flueki and Francis; whereas Adams-Harbertson uses “universal” standard c...

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Soil and Winegrape Quality in Biodynamically and Organically Managed Vineyards

American Journal of Enology and Viticulture

Prior to the organic agricultural movement, biodynamic agriculture was developed in the 1920s in ... more Prior to the organic agricultural movement, biodynamic agriculture was developed in the 1920s in response to concerns from farmers about the deteriorating soils and health of their farms (Steiner 1993). Similar to organic agriculture, biodynamics eliminates synthetic chemical fertilizers and pesticides. Biodynamics is a holistic approach that emphasizes soil building and high diversity of crops, animals, and wildlife habitat (Koepf et al. 1990); therefore, inputs from outside the farm are minimized and use of on-farm resources is optimized. In addition, biodynamic practitioners use a series of fermented manure, plant, and mineral-based preparations on soil, crops, and compost (Table 1). These substances are not claimed to act as fertilizers but are said to stimulate soil nutrient cycling and promote photosynthesis and optimal compost development (Koepf et al. 1990). Organic and biodynamic farming practices are increasing worldwide. As of 2002, 1.5% of U.S. grape acreage was certified organic (Green 2003) and organic methods continue to spread in both certified and noncertified acreage. Approximately 500 ha of winegrapes are certified biodynamic in the United States (H.G. Courtney 2003, Josephine Porter Institute, personal communication). Biodynamic wines have received growing attention in the past 10 years as some of the world's prestigious domaines have adopted the method. Growth in biodynamic viticulture has been particularly rapid in France, with 1000 ha of winegrapes cultivated biodynamically in 1993 and 15,000 ha in 1998 (Meunier 2001). Biodynamic farming, with its strong emphasis on soil building, holds many benefits in terms of sustainability and soil quality (Reganold et al. 1993, Mäder et al. 2002). Whether the unique biodynamic preparations themselves have any additional benefits is controversial, however. Research of the preparations suggests that they may benefit soil quality and crop quality (Koepf 1993, Reganold 1995), although results are mixed.

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An Enzymatic Assay for Acetaldehyde in Grape Juice and Wine

American Journal of Enology and Viticulture, 1981