ISG Sommelier flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Veraison

The stage in the vine cycle when grapes change color, soften, and begin accumulating sugar while acidity declines; it marks the start of ripening and guides harvest timing.

Potential alcohol conversion

Estimated by dividing grape sugar in grams per liter by about 16.83, or roughly 0.55 to 0.6 percent alcohol per degree Brix; used to plan picking and style.

Malolactic fermentation

Bacterial conversion of sharper malic acid to softer lactic acid by Oenococcus oeni, reducing acidity and adding buttery diacetyl notes, typical in red and some white wines.

Carbonic maceration

Whole-cluster fermentation under carbon dioxide without crushing, producing fruity, low-tannin wines such as Beaujolais; intracellular enzymes drive the initial fermentation inside intact berries.

Brettanomyces fault

Yeast contamination producing volatile phenols such as 4-ethylphenol and 4-ethylguaiacol, perceived as barnyard, leather, or medicinal aromas at higher concentrations.

Free versus bound SO2

Free sulfur dioxide is the active antimicrobial and antioxidant fraction; bound SO2 is chemically attached and inactive, and higher wine pH requires more free SO2 for the same protection.

Cabernet Sauvignon parentage

A spontaneous cross of Cabernet Franc and Sauvignon Blanc first identified in Bordeaux, combining structure and color from one parent with aromatic lift from the other.

Pinot family mutations

Pinot Noir is genetically unstable and mutates into Pinot Blanc, Pinot Gris, and Pinot Meunier, which explains the family's shared aroma profile and clonal diversity.

Traditional method sparkling

Second fermentation occurs in the bottle, followed by lees aging, riddling, and disgorging; this creates fine bubbles and yeasty autolytic complexity found in Champagne.

Tannin sources

Red wine tannin comes from grape skins, seeds, and stems plus oak barrels; it provides astringency, bitterness, and antioxidant protection that supports aging.

Fortified wine definition

Wine strengthened with grape spirit; Port stops fermentation to retain sugar, Sherry uses flor or oxidative aging, and Madeira relies on heat and oxidation.

Noble grape varieties

Vitis vinifera varieties such as Riesling, Chardonnay, Sauvignon Blanc, Pinot Noir, Cabernet Sauvignon, Merlot, Syrah, Nebbiolo, and Sangiovese, widely regarded as producing the finest wines.

TCA fault

2,4,6-trichloroanisole contamination from cork or winery surfaces, perceived as musty, damp cardboard, or wet newspaper at very low detection thresholds.

Volatile acidity

Elevated acetic acid and ethyl acetate produce vinegar or nail polish aromas; small amounts add complexity, but high levels indicate spoilage or oxidation.

Blind tasting logic

Deduction from structure: high acid with low alcohol suggests cool climate, while high tannin with high alcohol suggests warm-climate Cabernet, Syrah, or Nebbiolo.

Aroma threshold

The lowest concentration at which a compound is detected; recognition threshold is the higher level at which it can be identified, and both vary widely between individuals.

Decanting purposes

Separating sediment from older wines and aerating young tannic wines; prolonged aeration can flatten fragile older wines, so timing depends on age and structure.

Serving temperature bands

Sparkling 6-8 C, crisp whites 8-10 C, rich whites 10-13 C, light reds 13-16 C, full reds 16-18 C, and fortified wines 14-18 C.

Opening sparkling wine

Chill the bottle, hold at 45 degrees, keep a thumb over the cork while loosening the cage, then turn the bottle rather than the cork to control pressure release.

Classic service sequence

Present the list, take the order, show the bottle to the host, open and check, pour a taste for approval, then serve around the table in a defined order.

Standard pour sizes

Typical servings are 125-150 mL for still wine, 100-125 mL for sparkling, 50-75 mL for dessert wine, and 25-50 mL for spirits.

Food pairing principles

Acid cuts fat, sweetness balances heat and bitterness, tannin clashes with oily fish and salt, and umami amplifies bitterness and metallic notes.

Wine service order

Serve lighter before heavier, dry before sweet, white before red, young before old, and sparkling first unless a specific pairing dictates otherwise.

Beverage cost percentage

Cost of goods sold divided by beverage sales, multiplied by 100; wine programs commonly target 18-24 percent depending on concept and price tier.

Pour cost

The cost of one serving divided by its selling price; a 750 mL bottle yields five 150 mL pours, so bottle cost divided by five approximates pour cost.

Menu engineering matrix

Classifies items by popularity and contribution margin into stars, plowhorses, puzzles, and dogs, guiding pricing, placement, and menu changes.

Inventory turnover

Cost of goods sold divided by average inventory value; low turnover ties up capital and raises spoilage risk, especially for by-the-glass wines.

Ethanol calorie yield

Ethanol provides about 7 kcal per gram; a 150 mL glass at 13 percent alcohol contains roughly 14 g ethanol, or about 100 kcal from alcohol alone.

Standard drink definition

A standard drink contains about 10-14 g of pure alcohol depending on country; moderate drinking is generally defined as up to one or two drinks per day.

Sulfite labeling threshold

Wines above a set concentration, commonly 10 mg/L in many jurisdictions, must declare sulfites; sensitivity mainly affects a small subset of asthmatics.

PDO versus PGI

EU protected designation of origin requires all grapes from a defined area with strict rules; protected geographical indication allows more flexibility and at least part of production in the area.

US AVA labeling rule

An American Viticultural Area label requires at least 85 percent of the wine from that area; a varietal label requires at least 75 percent of that grape.