Week 2: Vegetables

Storage as the first decision a vegetable meets after the market: what belongs in the refrigerator and at what temperature, which producers of ethylene gas must be kept from which sensitive produce, and what the fat, protein and calorie content of a handful of common vegetables actually is.

1 March 2027

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A vegetable’s life after purchase is mostly decided by where it goes next, not by anything done to it at the stove — this week’s material sits entirely inside weeks 1 through 10’s preparation-only remit. Two mistakes are common and opposite: refrigerating something that does not tolerate cold, and leaving out something that spoils quickly at room temperature.

Families, briefly#

Vegetables are grouped here by what they have in common rather than by species: roots and tubers (potato, carrot), alliums (onion, already touched on in outline only — week 5 covers what cutting does to them), leafy greens (spinach, lettuce) and brassicas (broccoli, cauliflower, Brussels sprouts). The grouping matters because storage behaviour tracks the family more reliably than it tracks any single vegetable’s popularity. Cuts are noted only as they affect keeping quality this week — the knife has its own week, week 7, and this lecture does not pre-empt it.

Storage: shelf, drawer, cold or not#

Potatoes, sweet potatoes, whole winter squash and dry onions keep best somewhere cool and dark but not refrigerated — cold temperatures convert starch to sugar in a potato and shorten rather than extend its useful life. Leafy greens, most brassicas, carrots and herbs go into the refrigerator, ideally in the crisper drawer. The FDA advises keeping the refrigerator at or below 4 °C (40 °F) and the freezer at or below −18 °C (0 °F), checked with an appliance thermometer rather than assumed from the dial setting.

Within the refrigerator, a high-humidity crisper setting (vent closed) slows moisture loss and suits leafy greens; a low-humidity setting (vent open) lets moisture and ethylene gas escape, and suits produce that would otherwise soften faster in a damp, sealed drawer. The University of Arkansas Cooperative Extension Service’s consumer guidance puts leafy greens, broccoli and asparagus in the high-humidity drawer.

Ethylene: producers and the sensitive#

Ethylene is a plant hormone that accelerates ripening — and, past a point, decay — in whatever produce sits near it. The USDA Agricultural Marketing Service’s technical report on ethylene describes apples, bananas, avocados, pears, stone fruit and tomatoes as high producers; leafy greens, broccoli, carrots and cucumbers are sensitive to it rather than producing it. Separating the two groups — different drawers, or at minimum not sealed together in the same bag — is the single highest-value habit this week teaches. Week 9 returns to this same chemistry from the fruit side of the exchange.

Choosing well at market#

Firmness, colour and smell are the three checks worth making before anything goes in a bag: produce that is already soft, discoloured at cut edges, or smelling faintly fermented has already started a decline that storage can only slow, not reverse.

Common vegetables: calories, fat, protein and fibre per 100 g#

Nutritional composition is not a storage question, but this course’s invent-a-recipe assessment asks a student to reason about a dish’s composition before it is cooked, and vegetables are frequently the largest component by weight in a prepared recipe. Figures below are per 100 g of the raw, edible portion, drawn from USDA FoodData Central, the same database the assessment brief names, and grouped by the family groupings this week already uses.

None of the eight is a meaningful source of fat; the calorie content across this group tracks carbohydrate and water content rather than protein or fat — garlic’s comparatively low water content is why it is the outlier at 149 kcal, worth stating plainly rather than leaving a student to assume vegetables are interchangeable on this measure. The tutorial session’s macro calculator draws on five of these — onion, carrot, potato, spinach and broccoli — using the same per-100 g figures shown here, scaled to whatever quantity a recipe calls for; garlic, lettuce and cauliflower are not yet selectable in the calculator.

Outline#

• families and what they have in common, rather than species by species
• storage: shelf, drawer, humidity, and the fixed 4 °C reference point
• ethylene producers and the sensitive, and why they are kept apart
• choosing well at market
• calorie, fat, protein and fibre content per 100 g for eight vegetables spanning roots and tubers, alliums, leafy greens and brassicas, sourced to USDA FoodData Central