Impact of Multicolored Asian Lady Beetles on the Sensory Properties of Concord and Niagara Grape Juice

ABSTRACT: The presence of Multicolored Asian Lady Beetles (MALB) in grape juice is increasingly problematic. The overall objective of this study was to determine the specific sensory impacts of MALB on Concord and Niagara grape juice. The aroma threshold for MALB-taint in both juices was determined and expressed as the best estimate threshold (BET). The aroma BET for MALB-taint in Concord grape juice was 1.8 and 0.65 MALB/L Niagara grape juice. The specific sensory attributes of the grape juices influenced by the presence of MALB were then described. In Concord grape juice, trained panelists (n = 9) found significant increases in vegetal aroma and earthy flavor as MALB concentration increased from 0.45 to 7.2 MALB/L. In Niagara grape juice, with increasing MALB concentration, trained panelists (n = 8) indicated significant decreases in honey and sweetness with corresponding increases in sourness, astringency, and vegetal and earthy aromas and flavors (P < 0.05). For both aroma and flavor, consumer rejection studies were performed using paired preference comparisons of control juice to MALB-tainted grape juice. For Concord grape juice, consumers (n = 60) rejected the aroma of MALB-tainted juice at 1.8 MALB/L and the taste/flavor of the MALB-tainted juice at 3.6 MALB/L. For Niagara juice, consumers rejected the aroma of the juice at 3.6 MALB/L. This study demonstrated the presence of MALB negatively impacts the sensory properties of Concord and Niagara grape juice. Grape juice processors may use this research for quality control measures and for establishing tolerance limits. Practical Application: The Multicolored Asian Ladybeetle (MALB), initially used for biocontrol, has been shown in previous literature to impact the sensory properties of wines. The presence of MALB in grape juice is now becoming problematic; however, there is little research describing the specific sensory impacts of MALB on grape juice. This study examined the sensory impact of MALB on both Concord and Niagara grape juice. While the threshold and trained panel evaluations from this study provide valuable sensory profile information, grape juice processors may be particularly interested in the consumer rejection of MALB-tainted grape juice as they can use this research for quality control measures and for establishing tolerance limits.     

Aroma profile of Niagara grape juice contaminated with multicoloured Asian lady beetle taint using gas chromatography/mass spectrometry/olfactometry

The objective of this study was to determine the odour‐active compounds present in Niagara grape juice tainted with multicoloured Asian lady beetle (MALB: Harmonia axyridis: Coleoptera: coccinellidae). Niagara grape juice was made with (2.5 MALB/L) and without MALB and evaluated using solid‐phase microextraction coupled with gas chromatography/mass spectrometry/olfactometry (GC/MS/O) to tentatively identify compounds. Compared to the control juice, phenol, described as musty/mouldy, was found to be unique to the MALB‐tainted grape juice. The four odourants significantly higher in the MALB‐tainted grape juice were described as fruity, asparagus, stagnant water/chemical and musty/mouldy, tentatively corresponding to octanal, 3‐sec‐butyl‐2‐methoxypyrazine (SBMP), 2‐methoxy‐4‐methylphenol and decanal, respectively. Three of the five compounds found in the MALB‐tainted juice have been reported to be produced by live MALB. While past literature has focused on the contribution of 3‐alkyl‐2‐methoxypyrazines to MALB‐taint, the present study suggests other compounds, in addition to SBMP, may contribute to the aroma profile of MALB‐tainted grape juice.     

Occurrence and contribution of alkyl methoxypyrazines in wine tainted by Harmonia axyridis and Coccinella septempunctata

BACKGROUND: Ladybug taint (LBT) is a wine fault caused by the inadvertent incorporation of ladybeetles to the wine during the winemaking process. Harmonia axyridis, also known as the multicolored Asian lady‐beetle (MALB), was the only species considered responsible for causing the taint. A second species, Coccinella septempunctata (7 Spot), has recently also been implicated. The main objectives of this study were to identify and quantify the compounds associated with ladybug taint of white and red wine from these two Coccinellidae species (Harmonia axyridis and Coccinella septempunctata), and determine the most odor‐active compounds in LBT‐affected wines. RESULTS: Results show that Coccinellidae can contribute dimethyl, isopropyl, secbutyl and isobutyl methoxypyrazine to wine when they are processed with grapes, and that the methoxypyrazine composition varies between MALB and 7 Spot. Isopropyl methoxypyrazine is the major contributor to LBT in wines produced with these ladybeetle species, although secbutyl and isobutyl methoxypyrazine may contribute in MALB‐ and 7 Spot‐affected wines, respectively. Finally, dimethyl methoxypyrazine is reported for the first time in wines not affected by Coccinellidae; the global significance and prevalence of this compound in wine remains to be determined. CONCLUSION: Both Harmonia axyridis and Coccinella septempunctata can contribute alkyl methoxypyrazines, and particularly isopropyl methoxypyrazine, to wine at concentrations that can have a negative impact on wine quality. These findings will allow grape growers and winemakers to be more aware of the risks posed by 7 Spot beetles, and to take the appropriate preventative and remedial actions. Furthermore, this is the first time dimethyl methoxypyrazine is reported in wine, either as an endogenous or Coccinellidae‐derived odorant. © 2012 Society of Chemical Industry     

Detection Thresholds for 2-Isopropyl-3-Methoxypyrazine in Concord and Niagara Grape Juice

ABSTRACT:  2-Isopropyl-3-methoxypyrazine (IPMP) is the compound responsible for the off-flavor known as ladybug taint, which occurs when Harmonia axyridis beetles become incorporated with the grapes during juice processing. It is also an important grape-derived component of juice flavor in some varieties. The main objective of this study was to determine the orthonasal (ON) and retronasal (RN) detection thresholds for IPMP in juice. The ASTM E679 ascending forced choice method of limits was used to determine detection thresholds for 26 individuals in Concord and Niagara juices. Group best estimate thresholds (BETs) averaged 0.93 ng/L and were 50% and 21% higher in Concord than in Niagara juices for ON and RN evaluation, respectively. Group BETs for IPMP (ng/L) for Concord were ON: 1.11; RN: 1.02 and for Niagara were ON: 0.74; RN: 0.84. Variation in individual detection thresholds was observed, although familiarity with ladybug taint was not associated with individual threshold values. We conclude that humans are very sensitive to IPMP in juice, and that detection thresholds are more strongly influenced by grape variety than evaluation mode. These results may assist juice producers in establishing tolerance levels for IPMP in juice affected by ladybug taint or derived from grapes of suboptimal ripeness.     

Impact of Harvesting and Processing Conditions on Green Leaf Volatile Development and Phenolics in Concord Grape Juice

ABSTRACT: The disruption of plant cell walls during fruit juice processing results in the enzymatic formation of herbaceous-smelling green leaf volatiles (GLVs). Our objective was to assess the impact of thermal processing conditions on resulting levels of GLVs (hexanal, trans-2-hexenal, hexanol, cis-3-hexenol, and trans-2-hexenol), total phenols, monomeric anthocyanins, and percent polymeric color in Concord grape juice. The effects of fruit maturity and stage of juice processing on juice GLV content was also assessed. Of the GLVs studied, only trans-2-hexenal routinely exceeded its published sensory threshold in finished juice. We observed an inverse linear correlation between berry maturity (total soluble solids) and trans-2-hexenal levels in finished juice (P < 0.05, R ²= 0.91). Trans-2-hexenal was at a maximum immediately following crushing (569 μg/kg, >30-fold over detection threshold [DT]), decreased to 100 μg/kg following depectinization, pressing, and pasteurization, and to 32 μg/kg following cold-stabilization. The loss of trans-2-hexenal could be explained primarily by its reduction to trans-2-hexenol, which increased from 53 μg/kg after crushing to 500 μg/kg after cold-stabilization. High temperature pretreatment of must immediately following crushing (“hot break”) resulted in 5- to 6-fold higher concentrations of trans-2-hexenal in the final bottled juice as compared to conventional hot press. Contrary to expectations, no significant increase in phenolics and anthocyanins were observed in hot break conditions. These results indicate that hot break procedures may thermally inactivate enzymes responsible for transforming trans-2-hexenal under normal processing conditions and potentially alter the flavor qualities of the finished Concord juice. Different equivalent pasteurization regimes (82 to 93 °C) prior to bottling had no significant effect on GLV content of the finished Concord juices (P > 0.05). Practical Application: Introducing new processing techniques to fruit juice production can potentially result in undesirable changes to organoleptic properties. We have observed significantly higher levels of trans-2-hexenal, a potent herbaceous off-flavor, in Concord grape juice prepared with an initial high temperature heat treatment (“hot break”). Concord juice producers should be cautious in using hot break processing, especially with immature fruit, as it may result in persistence of green aromas in juice.     

Assessment of the validity of maturity metrics for predicting the volatile composition of Concord grape juice

Total soluble solids (TSS) are typically used as the sole metric for maturity of Concord grapes. However, the reliability of TSS in predicting the aroma composition of finished juice for grapes sourced from multiple sites has not been investigated. This study sought to determine the validity of TSS in predicting the aroma composition of the juice while also investigating other potentially useful indicators, including pH, titratable acidity (TA), and TSS:TA ratio. Grapes were harvested from 9 sites in the Lake Erie Concord Grape Belt and stratified from north to south and east to west. The key aroma compounds methyl anthranilate ("grapey") and trans-2-hexenal ("herbaceous") were quantified along with several other odorants. It was observed that while TSS was a robust predictor of monomeric anthocyanin content across sites, it was a poor predictor of aroma compounds in the finished juice. Conversely, pH, TA, and TSS:TA ratio were all significantly correlated with methyl anthranilate and trans-2-hexenal concentrations (P < 0.05) in samples equal to or exceeding 15 Brix, the industry minimum for grape maturity. These results indicate that parameters related to acidity are better predictors of aroma composition than TSS, which may aid in efforts to minimize herbaceous off-aromas and optimize the aroma composition of the finished juice.     

Consumer Acceptability of Fresh‐Market Muscadine Grapes

The objective of this research was to investigate the acceptability of muscadine grape (Vitis rotundifolia) genotypes (cultivars and selections) and to correlate overall liking to other quality measurements to determine the main drivers of liking. Twenty‐two genotypes grown at the Univ. of Georgia–Tifton Campus were evaluated. Four retail commercial grape genotypes (Vitis vinifera and “Concord”) were also evaluated for comparison. Panelists familiar with muscadine grapes used the hedonic general labeled magnitude scale (HgLMS, –100 = strongest disliking of any kind ever experienced, +100 = strongest liking of any kind ever experienced) to rate overall liking and the liking of appearance, flavor, pulp texture, and skin texture. Puncture testing was done to assess grape berry texture, and compositional attributes soluble solids and pH were also measured. The sensory results indicated that the grapes were variable with overall liking scores from 12.2 to 39.6. The factors highly correlated with overall liking scores were muscadine flavor, pulp and skin liking, while a significant negative correlation was found between skin liking and skin texture and mechanical texture measures. The muscadine grapes with the highest overall liking scores were Ga. 5‐1‐34 and Ga. 2‐8‐21. Principal component analysis confirmed that grapes with a thinner skin and a higher pH tended to group around overall liking and flavor points. These results indicate that even among panelists familiar with muscadine grapes, skin thickness is a negative characteristic. Breeding for thinner skins may be a positive step in muscadines gaining a more widespread appeal in the fresh fruit market.     

Sugars and Acid Analysis and Effect of Heating on Color Stability of Northwest Concord Grape Juice

Changes during storage in color of Concord grape juice extracted after heating to different temperatures and the carbohydrate and nonvolatile acid composition of Concord grapes were studied. Heating crushed Concord grapes under pilot plant conditions to 88° and 99°C inactivated nearly all of the polyphenoloxidase, increased the extraction of anthocyanins (ACN) and reduced polymeric color in the grape juice. During storage of the juice for 8 months, the rate of ACN degradation and color density decrease was the same in all samples. Glucose, fructose and sucrose were the only sugars found in Northwest Concord grapes, while malic and tartaric acids were the major nonvolatile acids. Lesser amounts of phosphoric, citric and coumaric acids were present.     

Identification of Predominant Aroma Compounds in Muscadine Grape Juice

The aroma components of muscadine (Vitis rotundifolia Michx) grape juice were analyzed by gas chromatography (GC)/mass spectrometry and GC/olfactometry (aroma extract dilution analysis). 2,5-Dimethyl-4-hydroxy-3(2H)-furanone (furaneol), with a burnt sugar-like aroma, was the most intense aroma in the juice. Other predominant compounds included 2,3-butanedione, ethyl butanoate, ethyl 2-methylbutanoate, 2-phenylethanol, and o-aminoacetophenone. These compounds were described as buttery/cream cheese, bubble gum/fruity, green apple/fruity, rosy, and foxy, respectively. Furaneol and o-aminoacetophenone were thought to be responsible for characteristic candy and foxy-like aroma notes of muscadine grape juice. Flavor dilution chromatograms were similar for juices prepared from grapes harvested on different dates and from different locations.     

DETERMINATION AND PREDICTION OF ODOR THRESHOLDS FOR ODOR ACTIVE VOLATILES IN A NEUTRAL APPLE JUICE MATRIX

ABSTRACT

Odor thresholds were determined for 10 odor active compounds (OAC) in apple juice, using three‐alternate forced choice methodology. Thresholds were determined in a neutral juice matrix by 25–30 panelists in duplicate at 22C. Individual thresholds were calculated using the best estimate threshold method. Group thresholds were determined using the geometric mean of the individual thresholds. OAC differed substantially in their concentration ranges, aroma thresholds (0.06–5.49 µL/L) and response rates (1.5–234.5% correct response/[µL/L]). Juice thresholds exceeded water thresholds by ～5–600 times. Multiple linear regressions were used to develop models to predict juice thresholds from water thresholds and physical constants, for apple juice (AJ) and published orange juice (OJ) values. The simplest most practical models utilized just one variable, the logarithm of the water threshold. Coefficients of correlation (R²) for the AJ and OJ models were 71.7 and 72.8%, respectively, and provided satisfactory estimates of juice thresholds.

PRACTICAL APPLICATIONS

This research established aroma thresholds in a juice matrix for 10 prevalent esters in apples and related them to water thresholds using log models. These thresholds allow industry to calculate more realistic odor activity values for quality control and research purposes in the apple juice industry.     

Improved Diet Quality and Increased Nutrient Intakes Associated with Grape Product Consumption by U.S. Children and Adults: National Health and Nutrition Examination Survey 2003 to 2008

Fruit contributes to dietary nutrient density and consumption of fruit in several forms (whole, dried, or 100% juice) has been reported to be associated with a healthier dietary pattern. The goal of this study was to examine the associations of the consumption of grapes (including fresh grapes, raisins, and 100% grape juice) with diet quality and food group/nutrient intake. A secondary analysis of Natl. Health and Nutrition Examination Survey (NHANES) 2003 to 2008 data was conducted to compare grape consumers (GC) with nongrape consumers (NGC) among children aged 2 to 19 y (n = 9622) and adults 20+ y (n = 12251). GC were defined as those who mentioned the consumption of fresh grapes, raisins, or 100% grape juice during 1 or both 24‐h recall interviews. Compared to NGC, GC had higher Healthy Eating Index 2005 (HEI‐2005) scores and higher intakes of total and whole fruit along with lower intakes of solid fat, added sugars, and calories from solid fats, alcohol, and added sugars (SoFAAS). Among adults, GC also had higher intakes than NGC of total and dark green/orange vegetables. Among both age groups, GC had higher intake than NGC of several key nutrients including dietary fiber, vitamin A, vitamin C, calcium, magnesium, and potassium. Consumption of grape products is associated with a healthier dietary pattern and higher intake of key nutrients by both children and adults.     

FLAVOR AND AROMA ATTRIBUTES OF RIESLING WINES PRODUCED BY FREEZE CONCENTRATION AND MICROWAVE VACUUM DEHYDRATION

This article describes the production of sweet dessert wines produced using late‐harvest freeze concentration, wine produced from fresh grapes frozen using refrigeration and wine produced from grapes partially dried using microwave vacuum dehydration. The objective was to compare the aroma and flavor attributes of the wines to determine the effect of each method of juice concentration. The replicated wine samples were evaluated by 12 experienced judges, and the wines were analyzed using solid‐phase microextraction. The microextraction detected 28 compounds; however, levels of concentration of these compounds were below published aroma thresholds. Although all the wines were judged as acceptable sweet dessert wines, the judges detected significant differences. The wine made from the dehydrated grapes exhibited lower fresh fruit aroma, higher fusel oils and oxidation, and flavor notes including citrus/grapefruit and acidity were lower.     

QUALITY AND STABILITY OF BLUEBERRY JUICE BLENDED WITH APPLE,GRAPE AND CRANBERRY JUICE1

Sensory quality and storage stability of blueberry juice blends were investigated with the goal of maintaining dominant blueberry flavor, aroma and color. Apple juice, Concord and Venus grape juices and cranberry juice cocktail were blended at 75, 50 and 25% with blueberry juice. As the percent of blueberry juice decreased, the intensity of blueberry‐related sensory attributes decreased. The 25% Concord and Venus blends were the only blends that resulted in blueberry flavor similar to the reference. Apple and cranberry juice cocktail blended with blueberry juice produced several blends with good flavor and aroma, but they were not readily characterized as blueberry juice. All blends at the 25% level produced blueberry color equal to or greater than the reference. The juice samples were evaluated initially and after three months of storage at 37C. After storage, all blends had decreased red color.     

GRAPE JUICE AS AN EXTENDER AND SWEETENER FOR BLUEBERRY DRINKS1

Blueberry juice has a strong flavor and low sugar content, but does not make an affordable, palatable drink unless mixed with water or another juice. This study investigated characteristics of blueberry juice blended with Concord, Reliance, Sunbelt, and Venus grape juices, and Thompson Seedless concentrate (TSC), The blends were evaluated by a trained sensory panel for the attributes of blueberry flavor, color, and aroma, and for astringency, body, and sweetness. Intensity of blueberry-related sensory attributes increased with increased concentration of blueberry juice for all two-way juice beverage blends. Blends sweetened with high fructose corn syrup (HFCS) as opposed to TSC were perceived as significantly different in triangle testing. In three-way blends of blueberry, Concord, and water, replacing HFCS with TSC as a sweetener, and increasing the percentage of blueberry and Concord juice increased intensity ratings for blueberry aroma, and the effects were additive. For the attributes of body, color, flavor, and sweetness, changing sweeteners had no effect, but increasing the percentage of blueberry and Concord grape juice increased the intensity ratings for these characteristics.     

CHEMICAL AND SENSORY PROPERTIES OF VERJUICE, A TRADITIONAL TURKISH NON-FERMENTED BEVERAGE FROM KABARCIK AND YEDIVEREN GRAPES

Verjuice is an unfermented green grape juice obtained by pressing green grapes. It has a unique flavor and sour taste. In the present study, parameters on the quality properties of verjuice made from Kabarcık and Yediveren grape varieties were studied; turbidity of fresh verjuice samples were 57.3 and 59.57 (625 nm %T), respectively. Phenolic matter contents ranged between 626.27 and 753.80 (mg/100 mL). In the samples treated with heat, clarified with gelatin and stored at 4C, the turbidity values were 81.20 and 93.10 (625 %T), and the total phenolic matter contents were 270.21 and 227.48 mg/100 mL in Kabarcık and Yediveren varieties, respectively. In addition, according to sensory evaluation, verjuice samples clarified with gelatin were preferred most by the panelists.

PRACTICAL APPLICATIONS

Verjuice is an unfermented green grape juice obtained by pressing unripe grapes with a unique flavor and sour taste. It is traditionally produced by pressing grapes and sieving the juice obtained through a nonmetal. It is preserved in bottles, adding olive oil to prevent contact with air, at cool condition. It is consumed locally, especially in the Mediterranean and southeastern regions of Turkey, to enhance the flavor of traditional meals, salads and appetizers, and as an ingredient in the production of various drinks, and several sausages such as mustard sausage. The natural verjuice that is neither clarified nor heated was more flavored, but it is turbid and has rather short shelf life. The present study revealed that clarification with gelatin followed by heat treatment of bottled verjuice at 85C for 15 min result in a favorable product with respect to quality properties during shelf life at ambient temperature.     

Volatile aroma compounds in wines from Chinese wild/hybrid species

The volatile aroma compounds in wines produced from Chinese wild/hybrid species were investigated in comparison to wines from European grapes. Volatiles were extracted by headspace solid‐phase micro‐extraction and identified by gas‐chromatography/mass‐spectrometry. The identification of analyte was performed by a combination of the linear retention index approach with the comparison of the obtained mass spectra. A total of 98 peaks were tentatively assigned as wine aroma components, and 15 odorants can be found at concentrations above their odor threshold among the odor activity values (OAVs) of 46 compounds evaluated in all of the wines. The “OAVs’ aroma wheels” showed that the classes of aromatic series are first fruity, next herbaceous and roasty and no spicy and caramelized notes. Via principal component analysis, all the grape germplasm studied could be divided into four groups: “Jingsheng‐1,” “Cabernet Gernischt,” “Beibinghong,” and others, which exhibited distinctive aroma features, respectively. Practical applications Chinese wild grape species have many desirable properties for wine grape breeding such as possessing strong resistant genes to fungal diseases and cold condition, especially after hybridization with European grapes. As an emerging wine country, wines from Chinese wild/hybrid species have achieved much success in the last few years. The chemical content and biological properties have been studied extensively in many but there are a few studies in our knowledge about the wine tastes of these species. In this paper, the key odorants in wines produced from the Chinese grape species of V. amurensis Rupr., V. davidii Foex., and V. quinquangularis Rehd. and its hybrids were characterized in comparison to wines produced from European grapes (V. vinifera). The findings will help to the further understanding of the key aroma components in the different Chinese grapevine germplasm, and make further efforts to enrich the wine types in the marketplace.     

Relationship between pectin methylesterase activity and the formation of methanol in Concord grape juice and wine

Pectin methylesterase (PME) activity in grapes was studied. Concord grape PME has optimum activity at pH 7·5 and the activity was the highest among several grape varieties tested. PME activity in Concord grapes increased continuously throughout the maturation period and reached a maximum at harvest. Consequently, this reflected the large amount of methanol formation during wine fermentation.     

Stereodifferentiation of geosmin in wine

Geosmin (trans-1,10-dimethyl-trans-9-decalol), a well-known, highly odorous compound, has recently been identified and quantified in red and sweet white wines, as well as in grape juice before alcoholic fermentation. Geosmin is a chiral compound and the (-) form is much more odoriferous than the (+) form. Enantioselective multidimensional gas chromatography analysis of a purified Cabernet Sauvignon wine extract revealed the presence of only one enantiomer: (-) geosmin. In grape juices obtained from rotten grapes and in wines this compound can be found at concentrations much higher than its olfactory perception threshold, indicating that it contributes to their earthy aroma. (-) Geosmin is also the only enantiomer to have been identified in pure cultures of Streptomyces sp. and Penicillium sp. strains isolated from rotten grapes.     

低温处理葡萄对爱格丽干白葡萄酒香气成分的影响

目的：以不同温度处理爱格丽葡萄原料,寻找增加爱格丽干白葡萄酒香气的最适温度。方法：以白色酿酒葡萄品种爱格丽为原料,16 ℃处理为对照,分别在4、－8、－20、－32 ℃条件下进行低温处理,采用小容器酿酒规范酿制葡萄酒并测定葡萄酒的理化指标,搅拌棒吸附萃取（stir bar sorptive extraction,SBSE）提取葡萄酒中的香气成分,再通过热脱附-气相色谱-质谱联用仪来定性和定量分析葡萄酒的香气成分,用SPSS 19.0软件进行香气成分的主成分分析（principal component analysis,PCA）,8 名经过培训的感官品尝小组成员对酒样进行感官评价。结果：低温处理能促使葡萄酒中香气成分种类的增加和含量的提高。结论：－8、－20 ℃低温处理葡萄可以显著提高爱格丽干白葡萄酒的香气质量,可在一定程度上使葡萄酒的香气更加浓郁。