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?

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.

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. I have more ambition than time, and 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.
• A link of sources

Sugar and acidity of rhubarb juice

So what does a winemaker need to know about rhubarb? The short answer is sugar and acid. Getting that right is the biggest part of any successful recipe. It turns out that rhubarb has a lot of acid and not much sugar. I juice the rhubarb and normally see measurments like this (these figure are from my most recent batch):

specific gravity (SG): 1.020, titratable acidity (TA): 14 g/L as tartaric, pH: 3.19

This agrees with Ben Rotter’s data:

SG: 1.020, TA: not enough data, pH: 3.17

Most of that acid, 70% or more, is malic.

Juice yield

A lot of people make rhubarb wine by fermenting on the fruit, and most recipes specify the amount of rhubarb by weight. To make sense of these recipes, or make wine with whole fruit, or to compare notes with other wine makers, you’ll need to know how much juice a given weight of rhubarb will yield. I got 515 ml (17.4 fl oz) of juice from 1.115 kg (2.5 lb) of fruit, or a yield of 462 ml/kg (7 fl oz/lb).

I froze the rhubarb, thawed it in a strainer and got 225 ml (7.6 fl oz) of “free run” juice. Then I lightly pressed, just squeezing with my hands, to get another 290 ml (9.8 fl oz). This is low compared to Mr. Rotter’s data (470 – 830 ml/kg). The pulp I discarded was wet, so I could have gotten more with a small press.

You know your own procedures better than I do. Do you efficiently squeeze the fruit leaving bone-dry pulp? Expect over 600 ml/kg (9.2 fl oz/lb). If you press lightly and leave wet pulp, then you’re more likely to get 500 ml/kg (7.7 fl oz/lb), give or take. Now we have some information on yield, sugar, and acidity. What can we do with these data?

The possibilities are endless

I normally make my rhubarb wine dry, and I can tell you it’s terrific that way. I’ve tasted sweet rhubarb wine that was fabulous. I’ve aged rhubarb wine over two years and noticed improvement. I’ve tasted 5+ year old rhubarb wine from the Montana Hutterites that was superb. I’ve heard that the Hutterites successfully age their wine for decades, and Ben Rotter aged a sweet rhubarb wine for 30 years, and it hadn’t past it’s peak. Many wine makers have found rhubarb to be an excellent blending wine.

This is what I mean when I say that rhubarb is versatile. That’s why no recipe can show you “what rhubarb wine tastes like”. To find out, you need to go beyond any one recipe and try different variations. Honey instead of sugar, sweet instead of dry, dry instead of sweet, high acid like a Riesling – and do set some bottles aside for extended ageing! While we’re on the subject of ageing, I wouldn’t recommend rhubarb as an early drinker. Even if you decide against extended ageing, you’ll want to give it at least a year.

Further reading

The Rhubarb Compendium - a good collection of rhubarb information
Improved Winemaking - Ben Rotter’s website – From his fruit data to ideas on wine styles, there’s a lot here for any winemaker

Weight and volume of table sugar

For other ingredients, I’m usually very interested in composition. How much sugar in 100 g of blueberries or how much, and what kind, of acid in 100 g of bananas. Table sugar is a component, so weight and volume conversions are a lot more useful than knowing that its a disaccharide of glucose and fructose. So here’s how to convert pounds of table sugar to cups (or kilograms to liters) and back again:

How to make a sugar syryp

It’s best to add sugar to wine or must by making a sugar syrup. In fact, it’s best to dissolve any solid additives in a little water before adding them to wine. It isn’t just that it’s a lot easier to fully incorporate the additive this way; it also keeps dissolved CO2 from quickly coming out of solution. Sanitizing is as easy as boiling & cooling (for small amounts use a pyrex measuring cup in a microwave oven).

You normally want to add only as much water as necessary, but how much is that? At room temperature, you can theoretically dissolve about 212 g/100 ml. That works out to a 1.122 lb/cup or about 2.5 cups sugar to 1 cup water (2.12 kg/liter which gives us the same ratio 2.5 liters of sugar to 1 liter water). That’s close to, but a bit more than, the standard recipe for a sugar syrup:

2 parts, by volume, of sugar to 1 part water will yield 2 parts of a 63º Brix solution (1.310 specific gravity)

Comparing sugar syrup to honey

You would combine sugar syrup and wine (or mead or must) the same way you would honey. In particular, you would use the same calculations to decide how much syrup or honey to add. You just need to know the specific gravity of each:

This is a post I should have written a long time ago. I don’t know about you, but I’ve looked up these details countless times – now we won’t have to.

Update 7/12/2010 – My own measurements

I measured the volume of sugar syrup made this way and it is very close to 2 parts.  I also wanted to measure the specific gravity. My hydrometer doesn’t go up that high, so I had to mix equal parts syrup and water. That weighed in at 1.160, which implies an SG for the syrup of 1.320 – very close to the predicted value.

Chocolate is available in different forms, like solid chocolate and cocoa, but they all have one thing in common: chocolate liquor. This is what cocoa beans become after modern processing gives them the flavor we’ve come to associate with chocolate. Add cocoa butter (fat from the cocoa bean) and you can make unsweetened solid chocolate. Add sugar to that, and you’ve got dark chocolate. Cut in some milk, or milk solids, and vanilla to get milk chocolate. I think it’s best to stay as close to chocolate liquor as possible and extract what we want from that to make our wine. I’m not saying that you should never add vanilla to you wine, just that we stay on topic. And when was the last time you felt your wine was really good, but it just needed a little milk?

Unsweetened dark chocolate or cocoa powder?

So, we might want to use unsweetened dark chocolate. We should also consider cocoa powder, which is chocolate liquor with much of the cocoa butter removed. The choice between the two probably comes down to how easy they are to work with and what we think of cocoa butter. Let’s take cocoa butter first. It’s the fat of the cocoa bean and it contributes the texture that we all love about chocolate bars. It doesn’t contribute any chocolate flavor though, so I don’t think the extra cocoa butter in solid chocolate does us any good in making wine. What would working with dark chocolate be like and how would that compare to working with cocoa? I find cocoa pretty hard to dissolve, and that’s how I’d want to incorporate it into wine. Dissolving dark chocolate would take some work too, though. It might be enough to break the dark chocolate into small pieces and add them to the fermented or fermenting wine, like oak chips. Done that way, dark chocolate might be easier to work with, but cocoa has less of the cocoa butter that we don’t want and all of the things that give chocolate it’s rich flavor.


Raw unprocessed chocolate sounds perfect, doesn’t it? But unless you’ve got a thing for bland and bitter, it really isn’t. The fermenting, drying, roasting, and grinding that is modern processing gives chocolate it’s rich flavors and aromas.Both are worth a try, but extract might be best
I haven’t mentioned chocolate extract yet, because its the form of chocolate that I know the least about. What I do know is that its got two things going for it: first, it has no cocoa butter at all. Second, it dissolves readily into most liquids. Those are two big advantages that set it apart from unsweetened dark chocolate and cocoa powder, but is there a catch? There might be and it revolves around the question of what exactly chocolate extract is extracted from. Some of my reading indicates that it is derived from dry fermented cocoa beans (which is how growers deliver cocoa to manufacturers) or even raw, unfermented cocoa beans. The label on my bottle of Star Kay White brand of chocolate extract is reassuring and says its made from “fresh roasted cocoa beans.” I take that to mean that the cocoa beans are fully processed, though possibly not yet finely ground into chocolate liquor. What I’m looking for is something as close to chocolate liquor as possible, without the cocoa butter, and while we’re at it, in a form that’s easily dissolved. This just might be it.


Phenolics?

Phenols are important components in wine that are responsible for color, bitterness, and astringency. They contribute some flavor and aroma and provide antioxidant activity. Even so, they are a tiny (0.05% – 0.35%) part of a wine’s makeup. Phenolic compounds are a bigger part of chocolate – 6% of chocolate liquor. Cocoa powder, because it is made by expelling much of the cocoa butter from chocolate liquor, has an even higher concentration – about 8%. Solid chocolate would have less than 6% because its made by adding cocoa butter and sugar to chocolate liquor. It’ll be important to keep the phenolic content in mind when deciding how much chocolate to use in the wine.

For some perspective, I’ll do a back of the envelope calculation of the phenolics in hot chocolate. The recipe on my can of Hershey’s Cocoa calls for two tablespoons of cocoa powder (10 g) in one cup (240 ml) of milk. Cocoa powder is 8% phenols by weight, and 8% of 10g is 0.8g. So we have a concentration of 0.8g/240ml, which is 3.33 g/L or 0.333% – what you might get from a tannic red wine. That’s why the recipe also calls for two tablespoons (about 25 g) sugar. That’s more than 10% residual sugar!

Stick around, we’re just getting started!

I’m going to put this information to use and start thinking about how to make a wine with chocolate. That’ll be the subject of my next article on chocolate wine. To make sure you don’t miss it, subscribe to this blog. Its the free and easy way to get each article as it’s published without having to check back all the time.

If you noticed something in the article that didn’t seem quite right, well maybe it wasn’t! Nobody’s perfect, and if I made a mistake in one of my calculations please let me know by leaving a comment. I’m planning to make this wine, and I want it to be a winner.

A better approach to a familiar problem

I’ve been trying to get a handle on the acidity in honey and mead. The problem, as I explain here, is that the normal tests, like titration, overstate acidity in mead because they include both the total amount of acid and the total amount of lactone. The last time I posted on the subject, I explained that those results can still be useful as an upper limit and outlined a procedure for managing the acidity in mead. What I really wanted to do was pin down the acidity accurately, and I had two ideas about how to do that. I’m going to use information from USDA 1261 to follow up on one of them today, and that is to use typical amounts of lactone in honey to correct measured titratable acidity values.

Dr White’s very useful data

Dr White determined the pH, amount of acid, which he called “free acidity”, the amount of gluconolactone, “lactone”, and titratable acidity, “total acid”, for 490 samples of honey.

Using the Lactone/Free Acid ratio to correct TA values

You might be wondering what the heck “meq/Kg” means. Well, rather than assume all the acid in any sample is tartaric, like most winemakers do, chemists express acidity as milliequivalents/Kg. This is a consistent, formal way of doing it that we’re not going to worry about because we’re not chemists and this article is getting technical enough. Besides, the really interesting part of the table is the ratio of lactone/free acid. This is exactly the information I was looking for and we can use it in two ways:

The average value of lactone/free acid is 0.335, and since total acid = lactone + free acid, free acid = total acid / 1.335. Now we can titrate a sample of mead, get a TA value that we know is overstated, and divide by 1.335 to get a corrected value.

Since the lactone/free Acid ratio varies, our correction will not be exact. We can use the average value and the standard deviation to get a range. The standard deviation is 0.135, which means, if these values are normally distributed, that almost 70% of the samples will have a lactone/free acid ratio between 0.200 and 0.470. From that we can corral the free acid in a range of total acid/1.200 and total acid/1.470.

An example

Let’s say you titrate a sample of mead and get a value of 7.5 g/L. You can use the simple correction of dividing by 1.335 to get 5.6 g/L or you can get a one standard deviation range by dividing by 1.200 and 1.470. That would give you a range of 5.1 – 6.3 g/L. I used 7.5 g/L in my example to tie it in with my earlier procedure of aiming for the high end of your target range. I illustrated this by looking at adjusting a mead’s acidity to match that of white wine. Since white wine can range from 5.0 – 7.5 g/L, I suggested aiming for 7.5, knowing that it would be less. Now we have a better idea of how well that would work because the one standard deviation range (5.1 – 6.3 g/L) puts it within the range of white wine.

Free acid has a huge impact on taste, and now that we know how to measure it, or at least estimate it well, we are well on our way to making better meads more consistently. I intend to continue this series on honey. To make sure you don’t miss these and other postings, subscribe to this blog. It’s easy, it’s free, and you’ll see every post without having to constantly check back.

What are cranberries like?

One cup (240 ml) of whole cranberries weigh about 3.5 oz (100 grams). Chop them up and they take up less space, so you can fit 3.9 oz (110 grams) into a cup. Fresh cranberries keep best when stored cold, just above 32F (0C). Phenolic content is high, up to 200 mg/100 g. Some of these phenolic compounds act as antioxidants, others, like benzoic acid, as antimicrobials. Total acid content is about 3 g/100 g, most of which is citric and malic, and they’re rich in pectin.

What’s in cranberries?

100 g of cranberries contain:

87.13 g water
12.2 g carbohydrates
0.39 g protein
0.13 g fat
0.15 g ash

Of the 12.2 g of carbohydrates, 4.04 g are sugar:

3.28 g glucose
0.63 g fructose
0.13 g sucrose

What does this mean for winemakers?

It means we’ve got some work to do in the sugar and acid department. Let’s assume that the juice yield will be equal to the water content of cranberries – call it 87 ml/100 g – and that all the sugar and acid will be in the juice. In that case, we’d get 87 ml of juice, containing 4 g of sugar and 3 g of acid. That puts the acidity of the juice at 34.5 g/L, as citric, and it means we’ve about 46 g/L of sugar. Converting it to more familiar units, we have a specific gravity (SG) of 1.015 (5 Brix) and a titratable acidity of 37 g/L, as tartaric.

I would approach this by diluting the juice, with sugar-water, until the acid is closer to normal – I might target 9 g/L in the must, which is still a little high but within the norm for a dry white wine. Combining one part cranberry juice with three parts sugar-water gets us to 9.25 g/L. How much sugar in the sugar-water? An SG of 1.090 implies about 240 g/L of sugar. We started with 4 g in 87 ml, which is 46 g/L, and diluted it to 25%. It turns out that three parts of 305 g/L sugar water to one part 46 g/L cranberry juice gets us 240.25 g/L.

That would be a good starting point. A larger than normal dose of pectic enzyme and a yeast that consumes malic acid, like Lavlin’s 71-B, would also be good ideas. I’ll think about this some more and pull it all together in a recipe soon.

Further Reading

Haraold McGee’s On Food and Cooking is a great book on the science of cooking. No recipes, but lots of information on ingredients, like cranberries and other fruits, and food chemistry. That makes it a great reference for the home winemaker as well as the home cook.

The USDA nutrient database is a great place to look up the composition of all sorts of common foods. They don’t have much to say about acidity, but still very valuable.