Boy, Peel Me a Grape!

(Originally published August 2006)

Wine is a pretty complicated topic. So, it’s easy to ignore one of the most fundamental questions regarding this miraculous, restorative elixir. That is, what is a grape? Just what are these things which grow on vines and eventually become something worthy of such attention (until you black out)? Let’s see!

Grapes are berries that grow on vines. So, technically we can call them members of the fruit food group. And, after all, this is a technical essay. Physically speaking, grapes are round or oval with smooth skin. They grow in bunches on the vine, in a variety of quantities, both within a bunch or among bunches. Grapes are the most commonly grown fruit in the world. Grapes more or less fall into five basic buckets as to how they will be consumed by humans: (1) Eaten fresh, soon after picking, as “table grapes.” These grapes are ripe, juicy and sweet. (2) Eaten dried, after the grapes have been picked for some time and become shriveled and the flavors concentrated along with perceptible sugary sweetness into “raisins” (the English word for shriveled grapes while in French the word “raisin” mean the basic “grape” itself). (3) Not eaten but instead pressed into grape juice which is then bottled and drunk. This concentrated juice is sweet but contains no alcoholic content. (4) Made into jams or jellies from the juice and pulp and eaten as a spread on other foods such as bread or crackers. (5) The only way that really matters, not eaten but instead pressed into grape juice which is then fermented into an alcoholic beverage called wine. Now we’re talking! This is why roughly 90% of grapes grown are used to make wine.

As Hanes has discussed ad nauseam elsewhere, there exists a vast number of grape types, not all suitable for (5) the production of wine. These grapes may be eaten as table grapes, raisins, drunk as grape juice or smeared all over bread or your body. What we would like to analyze now are the constituent parts of the grape berry typical of grapes made into wine. This might shed light on what wine is and why it possesses the flavors and textures it does. Or it might not.

At the outset of such discussion it’s interesting to consider the nutritional value of the grape before and after the fermentation process which creates wine. This is because lots of people eats table grapes to ingest their daily portion of fruits. While others (and maybe sometimes even the very same people) drink wine for health reasons. Science (surely not Hanes) is currently in the midst of plumbing what value table grapes and wine provides for human health, as well as, err, unhealth. This task remains ongoing. Fresh table grapes possess many vitamins and minerals which the human body likes. They can both add to general health and wellbeing or act to help prevent certain bodily ills, such as cancer or heart disease. Among the vitamins and minerals most commonly found in grapes are manganese, vitamin C, vitamin B1, potassium and vitamin B6 with additional phytonutrients such as resveratrol, quercetin, anthocyanin and catechin also present.

The latter phytonutrients are also known as compounds called flavonoids. Flavonoids are basically what not only contributes to the flavors of grapes and wine but also the textures and ability to change flavors and textures over time as wine ages. Now, to best understand how all these compounds and such exist and come into play, the various physical components of the grape need to be discussed.

Since this is about wine, hey, it’s not called The Hanes Grape Review, it gets tricky. Wine, she is never simple. With any discussion of wine and stuff like flavonoids one has to expand the topic to include parts of the grapevine such as the vine stems and leaves. This is because when grapes are fermented into wine these solids are often physically present in the fermentation vessel. The term for these things together with the non-juice parts of the grape itself is the pomace. Before getting into wine Hanes always thought that pomace was the thing you used to scrape dead skin off the bottom of your feet. Anyway. Taken as a whole, the pomace adds a lot of chemical properties to finished wine. And, unless you’re peculiar, you don’t eat the stems that table grapes are attached to when grape bunches are purchased in the grocery store, etc.

So, back to the grape berry we go. There’s three main parts of the grape berry, namely the flesh/pulp, the skin, and the seeds. We’ll start at the outside and work our way in. Witness, the skin. Or, rather, the parts of the skin. Again, never simple. The skin’s basic jobs are to protect the rest of the grape (to keep things out) and retain water (keep things in). It forms the entire surface area of the grape, save for the pedicel, or the part where the grape attaches to the stem. The skin is not one homogeneous thing, but rather is made up of layers. The outermost layer is called the bloom. It is made of waxes and the substance cutin and is really what any layperson would consider to be the “skin” of the grape. It does most of the work in retaining grape water content and resisting fungi and other bad things trying to get into the grape. Oddly, though, the composition of the bloom is beneficial to the growth of wild yeasts, something of major import to the fermentation of grape juice into wine. Below the bloom are layers of epidermis and hypodermis, the layers which contain most of the flavonoids and phenolics found in the grape’s skin. Notably among these are anthocyanins, which are responsible for the color of grapes, as well as tannins, which add structure and dryness to finished wine. To make things simple, let’s just say that the skin of the grape comprises about 10% of the weight of a fully ripened grape.

Unless you like sucking on seeds, the major and most important part of the grape is its flesh, or pulp. The technical term for it is the pericarp or mesocarp (the skin being the exocarp). Mmm, yummy pericarp! Basically, the flesh of the grape is an interconnected mass of cells called vacuoles. As with other living organisms, these cells are connected by tissues which share moisture, nutrients and all the other cool junk a grape needs to live and grow. The flesh of the grape is mostly juice, enmeshed by these thin tissues. A peripheral vascular “mesh” forms the outer part of the flesh, just beneath the skin. Note in passing that 99% of grapes’ flesh is colorless (being mostly water) and that the color in juice or wine only comes from the anthocyanins in the surrounding skins, released during the crushing of the grapes and ongoing fermentation process.

Hanes is going to get kind of controversial here. The above description of the grape flesh doesn’t really do justice to it. It’s technically accurate, sure, but this is also like the grape for the most part. Where the flavors come from, the flavors which differentiate grape types apart and (get ready) reveal the terroir of the grape’s place of origin. Pinot Noir is different from Grenache because of the physical composition of the grape. Some of this comes from the skins and seeds, in terms of tannins and color and such, but it’s the flesh which is the grape. So, while simple in physical composition the flesh is not simple. Just ask any priest. As important (especially to wine geeks), the flesh is also the part which holds the water and nutrients of the grape. These nutrients, minerals and such have flavor and come into the grape via the grapevine from the soil. That is, the soil’s composition effects the grape flesh’s composition. Which is one of the major factors in the concept of “terroir,” or, loosely put, a sense of place (factoring in soil, vineyard slope and drainage, sun exposure, wind, length of growing season, geez, so much…). The point being that what the grape is fed effects what the grape will taste like. The “food” gets located in the grape’s flesh. And the food differs from locale to locale.

OK, enough passion of the flesh. The last part of the grape are the seeds. The number, size and shape of grape seeds vary among varieties. The usual number of seeds is between one and four. With the exception of seedless varieties, which have zero. Duh. However, grapes used to make wine do have seeds and these are the ones we care about. The more seeds, usually the bigger the grape. Bigger grape means more flesh, means more juice, means more wine. This said, allowing for natural variances in normal grape berry sizes among grape varieties, some grape berries are naturally smaller while others naturally larger. Grape seeds consist of an embryo, endosperm, and coat. The coat is the outer, umm, coating of the seed. The embryo is, you guessed it, the part that could grow into a new plant. The endosperm does something important, Hanes is sure of that.

In the making of wine seeds are important because they will come into contact with the juice once the grape skins are broken and everything starts to get all mixed up. Seeds are harder to separate out from the juice than other larger solids such as stems or leaves or even skins. Seeds possess tannins. These tannins will effect the texture of the wine. If for some reason the seeds do not reach full maturity they will likely impart a sort of bitter or astringent texture to the wine called “greenness.” This is not good. They make a wine harsh and imbalanced. “Physiological ripeness” is the term for when all the grape’s parts are equally mature and ready for plucking. Immature seeds occur most often when hot weather causes the sugar levels in the grape flesh to spike, the flesh maturing faster than the seeds. Because sugars convert into alcohol in the fermentation process, if one wants a wine without too much alcohol the grapes must be picked before the sugar levels get too high. Even if the seeds have not yet matured fully. So, while seemingly innocuous, seeds actually can play a big role in what a finished wine is like.

Hanes is tempted to say that this is basically the grape in a nutshell. But then all the wisecrackers out there will ask Hanes to explain how the grape got in the nutshell. On the topic of nutshells, though, while not technically a part of the grape, it should be noted in passing that as the grape ripens and matures, external influences beyond the basic sun, wind and rain change the chemical and physical composition of the grape. So, this is still the grape we are talking about. Foremost among this is the gray mold called Botrytis cinerea. This fungus has a beneficial effect on grapes (beneficial, that is, if desired by the vineyard manager or winemaker) and is also known as “noble rot.” Through tiny filaments the fungus penetrates the grape berry’s skin and dehydrates it, in essence beneficially concentrating the sugars remaining within the berry. The result being a grape that when pressed produces honeyed flavors and ultra-concentrated sweetness. This is a naturally occurring phenomenon in many winegrowing areas around the world and is worth the mention as an example of how the physiognomy of the grape berry may be dramatically altered in its “natural” state. The basic components of the grape remain the same but phenomena such as Botrytis cinerea underscore that the grape can never be truly understood in isolation from its environment.

As with so much in life, the basic lesson is that not all grapes are born equal. They all have skin, flesh and seeds (ignoring Mr. Thompson and his ilk) but that’s where the similarities diverge. The types of skin, flesh and seeds will determine grapes’ future as quality wine or other less laudable ends. “Nature” then plays a role as a grapevine must be paired with a suitable terrain and environment while “nurture” in the vineyard allows the grape’s three components to all equally add their bit to a fully mature and healthy grape. These differences may seem important but one day, perhaps among a vineyard of Sultana or Concord grapes, will be born the Che Guevara of grapes who will lead grapes of any and all Vitis in raising their collective consciousness and overcoming the inequalities of birth, regardless of thickness of bloom, color of pulp, or number of seeds. All true wine lovers await this day of liberation.