Know Your Ingredients: Raspberries

You can make good raspberry wine without knowing much about raspberries. Lots of people, including me, have done it by following a recipe. But if you want to know why your favorite recipe does things the way it does, or if you want to create your wine from scratch, then you need to know more about the fruit. I tried to collect information about raspberries that’s relevant to making wine and put it in a convenient place you can bookmark.

First some basics: One cup (240 ml) of raspberries weigh about 4.3 oz (123 grams).1 Fresh raspberries keep best when stored cold, just above 32F (0C).2 If you’re making wine and you have the space, then I recommend freezing – they not only keep well frozen, but the freeze/thaw process aids in extraction. One more thing: unlike grapes, the acid in raspberries is almost all citric.

What’s in raspberries?


Raspberry and grape composition1
Component Raspberries Grapes
Water 85.75 80.54
Protein 1.2 0.72
Fat 0.65 0.16
Ash 0.46 0.48
Fiber 6.5 0.9
Total Sugar 4.42 15.48
Starch 0 0


The amounts are g/100 g, and do not add up to 100 because the test for each component is subject to experimental error. The USDA presents this data a little differently, by including a carbohydrate line item. They don’t actually test for carbohydrates, though, they just report the difference between 100 and the sum of water, protein, fat, and ash3. Ideally, it would equal the sum of total dietary fiber, total sugar, and starch. They do measure those three quantities, so I include them in place of the carbohydrate line item.

Sugar content is hard to measure

The amount of fiber is interesting because it might explain why you can’t rely on your hydrometer to gauge sugar content in raspberries. Almost all the soluble solids in wine grapes are sugar, but they are only about 30% sugar in raspberries. Adding acid content to total sugar only gets us to 50%, on average4. So what’s the rest? Take another look at that fiber line. Some of that fiber, the USDA doesn’t say how much, is soluble fiber and would make up part of the soluble solids.

Average Stats
Brix: 10.04,5,6
Sugar (g/100 g): 4.31,4,5
TA (% citric): 1.64
pH: 3.35,6

Making raspberry wine

What does all this mean? That raspberries are different from wine grapes in some important ways. Since most knowledge about wine making comes from making grape wine, we should start with those differences and how they might change our usual practices.

Because sugar is harder to measure in raspberries than grapes, you’re better off using an average value of 4.3 g/100g rather than a hydrometer or refractometer reading. Another big difference from grape wine is the high pectin content, so you should plan on a higher dosage of pectic enzyme – maybe 6x as much for the same weight. Finally, because each raspberry is a collection of many tiny berries, raspberries have a lot more skin and seed surface area than grapes. This means phenolic extraction will be very high, so I recommend juicing the raspberries and making the wine like a white or rose instead of fermenting on the skin.

So start with your juice. Measure the volume and titratable acidity (I’d expect around 16 g/L) and use 4.3 Brix (1.017 SG) as an approximate sugar content. Choose target values for alcohol and TA based on the style of wine your trying to make and your personal taste. Then determine the amount of sugar, water, and acid to add to your juice. I created the Wine Recipe Wizard just for this purpose.

If you’re making a dry wine, then all you have to do is make these additions and ferment to dryness. For a sweet wine stabilize and sweeten after your wine has cleared.

Sources

1) USDA National Nutrient Database Great information on the composition of many foods. I used the keyword “raspberries” and the food group “fruit & fruit juices,” and selected raw raspberries to find information for this post.

2) On Food and Cooking – Haraold McGee
An excellent book on the science of cooking. No recipes, but lots of information on ingredients, like raspberries and other fruits, and food chemistry. That makes it a great reference for the home winemaker as well as the home cook.

3) Documentation for USDA National Nutrient Database When you really want to know how the USDA determined the amount of fat in raspberries – or how and why they did anything in the nutrient database – look here.

4) Volatile Composition in Raspberry Cultivars Grown in the Pacific Northwest Determined by Stir Bar Sorptive Extraction-Gas Chromatography-Mass Spectrometry – Sarah M. M. Malowicki, Robert Martin, and Michael C. Qian
Measures the composition of raspberries grown in Washington in 2005. Includes good data on sugar, acid, and soluble solids.

5) Raspberries And Related Fruit – Dr. Marvin Pritts
Does not report direct measurments, but indicates that “typical” raspberries will weigh in at 9 Brix, which agrees with Malowicki et al, have a pH between 3.0 – 3.5, and will contain 5-6% sugar. That’s a higher sugar content than Malowicki but significantly less than if the soluble solids were 100% sugar.

6) Raspberry Wine Recipe – One of my own raspberry wines.

Notes and Further Reading

The Average Stats table is just me with a calculator trying to boil down the tables, ranges, and approximate values of my sources into a simple useful number. Here are sources that I wanted to track down, but couldn’t for one reason or another:

  • Boland, F.E., V. Blomquist, and B. Estrin. 1968. Chemical composition of fruits. J.A.O.A.C. 51: 1203.
    Chemical composition of strawberries, red raspberries, blackberries, black raspberries, boysenberries and cranberries is presented. Analysis included total soluble solids, ash, K2O, P2O5, invert sugar, protein, citric acid and amino acid.
  • Leinback, L. R.; Seegmiller, C. G.; Wilbur, J. S. 1951. Composition Of Red Raspberries Including Pectin Characterization. Food Technology 5:51
  • Spanos, G.A. and R.E. Wrolstad. 1987. Anthocyanin pigment, nonvolatile acid, and sugar composition of red raspberry juice. J. Assoc. Off. Anal Chem. 70(6): 1036.


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