A glass of fermented grape juice is a beverage that people from omnivore to vegan ought to be able to enjoy, right?

During a discussion about winemaking techniques last week, my students were shocked to learn that animal products are often used in the production of their glass of grape juice.

We had a discussion so heated, I was afraid we would melt the wine glasses. Vegetarians and vegans can rejoice, as a number of today’s culinary students are interested, and personally invested, in a vegetarian/vegan lifestyle. I see many excellent restaurants serving plant-based cuisine in our future.

Animal products such as egg whites, casein (derived from milk), gelatin (from cows or pigs) or isinglass (from fish) may all be used to help make wine more stable or to remove particulate matter to make wine clear. These act as processing agents and are removed from the wine before bottling.

Since they do not remain in the wine, they are not ingredients and are not part of the finished wine. Many of these products have been used for hundreds of years.

The issue, though, is that people who choose not to consume animals or animal byproducts usually do so as a personal choice. Their intention not to harm animals means they are not willing to consume a product that has used any animal products. A vegetarian might be OK knowing that egg whites were used as a fining, or clarifying, agent, while a vegan may not.

The discussion about labeling for wine’s ingredients, nutritional information and processing agents is going on in every wine-producing country. A thorough discussion of the challenges and issues required by mandatory labeling would take up every inch of space in a Wednesday food section.

Ask any wine retailer how much time is spent trying to correct consumers’ misunderstanding about something as simple as sulfites in wine, and you’ll get an idea of the potential confusion caused by listing ingredients or processing agents on a bottle of wine.

And is there any demand for the information? Chris Woodrow, owner of The Vin Master, a wine shop in Atherton Mill with a focus on wines that are produced in an environmentally friendly way, says that he gets requests for vegan wines once every couple of months. It’s a challenge to find out from the producers what processing agents were used, so he steers shoppers toward “natural” wines that are unrefined and unfiltered.

And yet, if you care about this issue, don’t you have a right to know? While the information may not be on the label, there are resources available to the interested drinker. Start at PETA.org, where a list of resources and online vegan wine merchants is posted. There are wineries that have a reputation for wines that are vegetarian/vegan friendly. Australia’s Yalumba, for example, is well known for its animal-free production methods.

If the interest from my students is an indicator, growing interest in knowing how wine was made is likely to shape the way wineries communicate with their consumers.