The Potential Health Benefits of Phenolic Wine

Our progress is as follows:

  1. Establish the levels of resveratrol and other phenolics are present in commercial wines (where specific data is not available). Over 180 wines have been analyzed for both resveratrol and other phenolics by HPLC and this data is being compiled into a manuscript. The resveratrol levels were described in the mid-year report.
  2. Investigate plant levels of resveratrol where specific data is not available, (in collaboration with Andrew Walker) After a frustrating initial effort we have now developed a procedure to carry out this analysis. However, interest in resveratrol has waned due to the lack of any data demonstrating that is has much health impact, and we may not proceed with characterizing the levels in many grape samples. We have found a resveratrol derivative, piceid, previously unknown in grapes, and will look at a few wine samples for this compound to see if it is also present there.
  3. Assess the translocation of resveratrol in the grapevine and the prospect of controlling the levels of resveratrol in grapes, (in collaboration with Doug Adams) This goal was not met, and given the waning interest in resveratrol, will not now be attempted.
  4. Determine how the levels of resveratrol and other specific phenolics are affected by wine making treatments. This goal was partly met in a preliminary study and another project to be completed this summer will show how efficiently resveratrol is transferred from grape to wine in the fermentation process.
  5. Screen all phenolics in wine for potential anti-oxidative capacity. Determine how these materials could be isolated from grape waste material/pomace.(in collaboration with Frankel and Kinsella) The first part of this project is now nearly complete, and the second part, a rather significant undertaking, will be investigated next year in collaboration with an industry partner.
  6. Test the specific anti-oxidative potential of promising components from the screening using other tests that would be directly related to a health impact, (in collaboration with Frankel and others) This work is still in progress, but has been partly completed by analyzing the potency of known compounds from wine. That study is will be complete after one or two more compounds are tested after isolation from grape juice.

Spiders in Vineyard Agro-Ecosystems

The overall goal of this research project is to continue to elucidate the ecological roles, along with the potential economic value, of spiders in vineyard agro-ecosystems. Key objectives include determining which spider species in the grapevine canopy are also associated with vineyard cover crops, and further delineating the patterns of abundance and distribution of important vineyard spider species compared with population patterns of key insect pests upon which they may feed. One clear pattern beginning to emerge is an inverse relationship between spider and leafhopper densities in vineyards. Our findings demonstrate that when spiders are abundant, leafhoppers generally tend to stay below economically damaging levels. Another noteworthy discovery involves an apparent correlation between western grapeleaf skeletonizer (WGLS) mortality and occurrence of the clubionid spider Trachelas pacificus. Corrugated cardboard bands wrapped around vine trunks are very attractive to WGLS larvae seeking pupation sites. These bands also harbor large numbers of Trachelas. especially juveniles. Data suggest an inverse correlation between WGLS and Trachelas numbers in the cardboard bands (high spiders / low WGLS, and vice versa). The most abundant spiders sampled in the grapevine canopy from early June through October belonged to the family Clubionidae (two-clawed hunting spiders): Trachelas pacificus and Chiracanthium inclusum. along with the thendiid spider Thendion. It should be noted that the most abundant spiders commonly detected in both cover crops (pitfall trap samples) and the grapevine canopy (shakecloth samples) were Trachelas and the much smaller micryphantid spiders. Sampling trials conducted “around-the-clock” (6A, 12N, 6P, 12M) during both 1992 and 1993 revealed no clear pattern of differential spider activity or variable likelihood of collecting particular spider species at different times of the day.

The Effect of Application and Timing of Kryocide on Fluoride Levels in Wines

The main purpose of this experiment was to investigate the relationship between various rates and timings of Kryocide applications on a red and a white winegrape variety and possible fluoride levels in finished red and white wines made from those treated grapes. In addition, the efficacy of Kryocide under these new treatment regimes and recommendations following the outcome of the experiment were other objectives. The presence of fluoride in wines has been specifically identified as a problem to the wine industry in the past three years. Preliminary research at CSU Fresno in 1990 and 1991 has shown that there is a correlation between Kryocide applications at bloom and fluoride levels in wines made from Kryocide-treated grapes. However, due to O.I.V. stipulations, further research has been requested to see if lower rates and/or timings would be effective in: (1) keeping fluoride levels below the 3 ppm limit, and (2) controlling Western Grapeleaf Skeletonizer and Omnivorous Leafroller, the two major insect pests controlled by Kryocide. The results indicated that applications of Kryocide made later than at bloom, and multiple applications of Kryocide, contribute to increased levels of fluoride in wines made from those treated grapes. Particularly, a triple application of Kryocide, which put on a total of 19 pounds of Kryocide per acre (T5), had significantly higher amounts of fluoride in the wine than any other treatment.

Reducing Bitterness In Wines. The effect of wine composition, sample evaluation method and salivary flow on sourness, bitterness and astringency

The effect of method of sample evaluation on sourness, bitterness and astringency was explored in water and in wine. The temporal responses using “sip and spit” procedure (the normal lab protocol) were compared to the TI responses when samples were sipped and swallowed, more similar to actual consumption method. With the exception of astringency in wine, no differences between the two methods were found. When samples were swallowed, astringency intensity was slightly lower and the total duration of astringency was slightly shorter, than when the samples were expectorated. However, considerable variation among judges occurred in this very small number of judges, thus this effect is not be concluded to significantly affect perception based on this preliminary study. To explore the effect of rate of salivary flow on TI perception of these three attributes, sourness, bitterness, and astringency were evaluated using expectoration. No significant differences were seen among flow groups, in contrast to a previous study in which high flow judges tended to have a shorter persistence of bitterness or astringency than low flow judges. To determine if any real effects of salivary flow occur, a larger number of subjects needs to be examined and a method for standardizing their sensory ratings over times must be found. Bitterness and astringency of epicatechin and catechin, the monomeric isomers (flavan-3-ols) of the phenols found in wine, were evaluated by both scalar and temporal methods (TI). By both, epicatechin was shown to be more intensely bitter than catechin, and by TI, bitterness lasted longer for epicatechin than catechin. While no difference in astringency was found by scalar tests, by TI, at higher concentrations, epicatechin had higher maximum astringency and longer duration of astringency than catechin. Both compounds were more bitter in 5%ethanol than in water, although the astringency did not vary significantly. The implications of these results for predicting wine flavor are unknown. On-going research in our lab is addressing differences in the tastes and intensities of different polymers of these two compounds in wine.

An Appraisal of Liquid Chromatography-Mass Spectrometry for the Analysis and Tracking of Wine and Grape Components-Extension

The consumption of wine may explain the unaccountably low rate of heart disease in parts of France. This suggests a cardioprotective effect for wine. One theory to explain this phenomenon is that the phenolic antioxidants found in wine inhibit LDL lipid oxidation, the initial stage of atherosclerosis. Wine antioxidants are more potent than vitamin E (known to reduce heart disease) in preventing LDL lipid oxidation, supporting this theory. The amount of these phenolic antioxidants in two glasses of wine could significantly increase the total levels of these compounds in the American diet. Phenolic antioxidants like those in wine have also been shown to reduce cancer rates and, in-vitro, inhibit many basic mechanisms of carcinogenesis. Further studies are needed to establish a causal link between wine consumption and disease prevention. Analyses of Wine Components that May Reduce Disease Our results this year were quite satisfactory. Our first success was developing an analytical procedure for the analysis of resveratrol by HPLC. This procedure was accepted for publication in the Journal of Agricultural and Food Chemistry Resveratrol is one wine component which has been implicated as a anti-atherosclerosis compound. As part of the study to develop a procedure we analyzed for resveratrol in a dozen California wines and found higher levels in Pinot noir than Cabernet Sauvignon and Zinfandel. Our large scale analysis now underway will tell whether or not this is a real trend. A study that is directly relevant to the health effect was carried out by studying the anti-oxidant capacity of wine phenolics. As mentioned above, it is the property of being an antioxidant, that is most likely to be the key to any health benefit from wine. In the experiment we carried out, we tested the ability of these wine antioxidants to prevent the oxidation of human LDL lipids. It is this event, the oxidation of LDL lipids, that is supposed to lead to atherosclerosis, the cause of most heart disease mortality. Thus, anything that prevents the oxidation from occurring is a candidate for preventing heart disease.

Interaction of commercial wine yeasts and malolacric bacteria

Twenty-nine strains of malolacric bacteria and forty-three strains of wine yeasts have been obtained and placed in the departmental culture collection as source material for this project. Nine diffusion type assays for screening yeast/bacterial interactions have been examined using various media preparations. For yeast strain influences on lactic acid bacteria, the Circular Surface Inoculation using a dilute grape juice medium has already shown some antagonistic relationships with the few strains tested. Unfortunately, the Circular Surface Inoculation Assay may not prove to be satisfactory for determining the influence of LAB producer strains on yeast target strains as the yeast grow too rapidly and develop a lawn before LAB growth occurs.