Thermal Pre-Treatment of Non-Alcoholic “Wine-like” Beverages Create a Functional Food Without the Buzz

We’ve all read about the health benefits of red wine.  Antioxidants and polyphenols in wine have been shown to benefit many different health concerns, including (but not limited to) cancer, cardiovascular diseases, neurodegenerative diseases, and obesity.  Because of these vast health benefits, there has been a great interest in creating what is known as a “functional” beverage: wine fortified with antioxidants, polyphenols, or resveratrol, in order to further increase the health benefits of the beverage.  In fact, in North America between 2002 and 2007, the market for functional beverages increased by 73%.

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What about those that like the taste of wine, but for one reason or another cannot (or should not) be consuming alcohol and still would like the health benefits without having to take a pill?  Or maybe for those who want wine at 9am but feel too guilty about having alcohol that early in the morning?

One recent study aimed to address this by developing a non-alcoholic “wine-like” beverage from grape juice blends that possessed the same health benefitting compounds that red wine contains.  Another goal of this study was to examine heat application to the grape prior to processing, which studies have shown to result in an increase in health-benefitting anthocyanins and stilbenes, and also what the optimum time/temperature combination treatment is in order to maximize antioxidants/polyphenols without damaging the sensory characteristics of the beverage.

One final goal of this short study was to prepare blends that were “wine-like” in both appearance and flavor (astringency and tartness), and that were also high in antioxidants.

Methods

The grapes used for this study were the hybrids “Castel 19637”, “Lucie Kuhlman”, and “Sovereign Coronation”, from Nova Scotia, Canada.  For the optimization of heat portion of the study, only the “Sovereign Coronation” grapes were used.  For comparison, a commercial grape juice from a local market was purchased.

For the heat treatments, grapes were first cut into 2-4mm slices using a vegetable chopper and then heated in a convection oven.  The time/temperature treatments were set as follows: 1) 60oC for 30min; 2) 60oC for 60min; 85oC for 30min; and 85oC for 60min.  After heating, grapes were pressed using a stainless steel fruit squeezer, and then the juice was filtered through 4 layers of cheese cloth.  The juice then underwent physiochemical, biochemical, and antioxidant analysis to determine the optimum time/temperature combination.

To create the blends, a wine pressing ratchet was used to press 20kg of sliced, heat-treated grapes (heated at 65oC for 30 minutes, as was determined by studies to result in the highest level of bioactivity for these varieties of grapes).  The juice was then hot-filled into sterilized containers and stored at 4oC for less than 10 days before further analysis.  The four blends created were as follows: 1) “Castel 19637”: water (3:2); 2) “Castel 19637”:”Sovereign Coronation”:water (2:1:0.5); 3) “Castel 19637”:”Lucie Kuhlman”: water (2:1:1); and 4) “Castel 19637”:Lucie Kuhlman”: “Sovereign Coronation”: water (2:1:1:0.25).

The following chemical parameters were measured: total soluble solids (TSS, oBrix), titratable acidity, color, common sugars (sucrose, glucose, fructose), organic acids, phenols (flavonols, flavan-3-ols, anthocyanins, and stilbenes), antioxidant capacity, and anthocyanins.

Sensory analysis was performed using students and staff at the Nova Scotia Agricultural College who were pre-screened for their ability to detect sweetness, sourness, astringency, and texture.  There was a total of 18 panelists, 8 men and 10 women, aging from 19-50 years old.  The panelists were further trained on the characteristics of sweetness, sourness, astringency, viscosity, and color.  For color comparisons, a reference sample of Merlot (Donini Collection, Milano, Italy) was provided.  Descriptive analysis was performed by evaluating the wine characteristics in the following order: color, astringency, sourness, sweetness, and lastly, viscosity.

Results

Heat Treatment on Phenolics of Grape Juice

  •       Heat treatments increased the TSS and titratable acidity (TA) of the grape juice.
  •       The timing and the temperature of the treatments were directly proportional to increases in TSS and TA.
  •       There were no differences in the TSS:TA ratios of any of the heat treatment combinations.
  •       Heat treatments increased the concentrations of total anthocyanins in the grape juice.

o   The most intense heat treatment (85oC for 30min) increased anthocyanins 26x, relative to an unheated control.

o   Heating at 65oC for 30min or 85oC for 15min increased the concentrations of total flava-3-ols, flavonols, and stilbenes compared to an unheated control.

  •        The 65oC for 30min treatment before pressing the grapes resulted in the most palatable beverage with higher levels of total flava-3-ols, flavonols, and stilbenes.

o   Even though higher temperatures/times resulted in greater polyphenol concentrations, the taste was not acceptable due to very sour and caramelized flavors.

o   Based on these tests, the 65oC for 30min treatment was used to prepare the grapes for the blend and sensory portion of the experiment.

Grape Juice Blends

  •       The TSS ranged from 13.3 to 18.2 in the four blends.
  •       The TA ranged from 0.75 to 1.15 in the four blends.
  •       The “Castel 19637”: water blend had the lowest concentrations of sugars, TSS, and TA, though it did have the highest TSS:TA ratio.
  •       There were no significant differences in anthocyanin concentrations between any of the blends.

o   The commercial grape juice contained significantly lower anthocyanins then the “wine-like” blends.

  •       The color intensity of the “Castel 19637”:”Lucie Kuhlman”:water blend was greater than the “Castel 19637”:”Sovereign Coronation”:water blend.
  •       All blends had similar levels of flavonols, flavan-3-ols, and anthocyanins.
  •       All blends had significantly higher levels of flavonols and flavan-3-ols than the commercial grape juice.
  •        The antioxidant capacity was lowest with the “Castel 19637”:”Sovereign Coronation”:water blend, and similar among the other three blends.

Sensory Analysis

  •       There were no significant differences in the hue and color intensity between any of the blends.
  •       The two blends “Castel 19637”: water and “Castel 19637”:”Sovereign Coronation”:water were scored the lowest for sweetness, suggesting these were the most “wine-like”.
  •       The blend of “Castel 19637”: water had significantly lower sourness than the blend of “Castel 19637”:”Sovereign Coronation”:water.
  •       The astringency was higher in the blend of “Castel 19637”:Lucie Kuhlman”: “Sovereign Coronation”: water than the blend of “Castel 19637”: water.
  •       All four blends were rated similarly in taste acceptability.

Authors’ Conclusions

Overall, the most optimum time and temperature pretreatment of grapes (before pressing) in order to increase the polyphenol concentrations without harming the taste/flavor of the wine-like beverage was found to be 65oC for 30 minutes.  When considering all the factors together: phenolics, antioxidant capacity, sugar content, and sensory analysis, the blend that was found to be most suited as an acceptable wine-like beverage was the blend containing the hybrid grape “Castel 19637” and water at a 3:2 ratio.

Thoughts

One thing the authors did not do was compare the polyphenol levels, antioxidant capacity, etc, to “real” wine.  I’d be curious to see how the two compared, and if the “wine-like” beverage was actually comparable to a “real” wine, except without the presence of alcohol.  I’m also really curious to know what this type of beverage actually tastes like! From the sensory analysis results, it sounds as though it is an acceptable alternative to “real” wine.

Does anyone out there have any experience with this type of beverage?  I’d really love to hear your thoughts!

If you have any comments about this short and sweet study, please feel free to leave your comments below.

Source: Ratnasooriya, C.C., Rupasinghe, V., and Pitts, N.L. 2012. Physiochemical and Sensory Evaluation of Non-alcoholic Wine-like Beverages Prepared from Selected Grape Cultivars. Journal of Nutrition and Food Sciences 2(1).

DOI: 10.4172/2155-9600.1000119
I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!