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Fennema's Food Chemistry · Chapter 8 · Vitamins

Vitamins

Micro, essential — and the easiest to lose in processing

Fat- vs water-solubleStability matrixProcessing losses6 minigames inside

Three minutes of blanching…

Vitamin C can drop by more than half, folate almost vanishes.
Why do some vitamins collapse on contact with heat, light, oxygen or water, while others endure? The answer is in their chemistry.

8.1 Introduction

Vitamins: four functional roles

From a food-chemistry view we care most about maximizing retention — less leaching, less oxidation, fewer reactions with food constituents.

①

Coenzymes

B-group: thiamin, riboflavin, niacin, B6, B12, folate, biotin.

②

Antioxidant defense

Vitamin C, certain carotenoids, vitamin E.

③

Genetic regulation

Vitamins A and D (act hormone-like).

④

Specialized roles

A in vision, ascorbate in hydroxylation, K in carboxylation.

8.7 / 8.8

Two families: fat- vs water-soluble

Fat-soluble: A · D · E · K

Stored in body fat & liver → toxicity risk in excess (A, D)
Lost by oxidation along with fats; mostly light- & air-sensitive
Main losses via fat oxidation, frying, refining

Water-soluble: C · B-group

Poorly stored → need daily intake; excess excreted in urine
Biggest killer is leaching — into the cooking water
Many are heat- & alkali-sensitive (thiamin, folate, vitamin C)

🎮 MINIGAME · CLASSIFY#1

Is this vitamin fat- or water-soluble?

Click the category button on each row.

Vitamin A (retinol)

Vitamin C (ascorbic acid)

Vitamin D

Thiamin (B1)

Vitamin K

Riboflavin (B2)

🎉 Done! Mnemonic: fat-soluble = A·D·E·K (DEKA) — stored, oxidation-prone, toxic in excess; everything else is water-soluble (C + B-group) — leaches out, needed daily.

Table 8.1 · click headers to sort

Vitamin stability matrix (Fennema Table 8.1)

Vitamin	Neutral	Acid	Alkaline	Air/O₂	Light	Heat	Max cooking loss
Vitamin A	S	U	S	U	U	U	40%
Ascorbic acid (C)	U	S	U	U	U	U	100%
Biotin	S	S	S	S	S	U	60%
Carotenes	S	U	S	U	U	U	30%
Choline	S	S	S	U	S	S	5%
Vitamin B12	S	S	S	U	U	S	10%
Vitamin D	S	S	U	U	U	U	40%
Folate	U	U	U	U	U	U	100%
Vitamin K	S	U	U	S	U	S	5%
Niacin (B3)	S	S	S	S	S	S	75%
Pantothenic acid	S	U	U	S	S	U	50%
Vitamin B6	S	S	S	S	U	U	40%
Riboflavin (B2)	S	S	U	S	U	U	75%
Thiamin (B1)	U	S	U	U	S	U	80%
Tocopherols (E)	S	S	S	U	U	U	55%

S=stable, U=unstable (significant destruction). Note niacin is stable to heat/light/air yet still loses 75% in cooking — because it leaches into water. Stability ≠ retention.

🎮 MINIGAME · MCQ#2

By Table 8.1, which vitamin is stable (S) to almost everything — neutral, acid, alkali, air, light, heat?

✔ Correct: niacin — chemically very stable (all S). Yet it still loses ~75% in cooking because it is water-soluble and leaches out. 'Chemically stable' ≠ 'well retained'. By contrast C and folate are unstable to nearly everything (up to 100% loss).

🎮 MINIGAME · MATCH#3

Match each vitamin to its deficiency disease

Click a vitamin, then its deficiency.

Vitamin

Deficiency

🎉 All matched! These deficiencies — e.g. pellagra, once endemic in the U.S. South — drove the enrichment of cereal-grain products.

🎮 MINIGAME · SORT#4

Order these by maximum cooking loss, high → low

Drag rows to reorder, then press Check.

↑ most lostmost retained ↓

≡Vitamin C

100% — unstable to heat/air/light AND leaches

≡Riboflavin (B2)

75% — light-sensitive, leaches

≡Vitamin K

5% — very robust (fat-soluble, heat-stable)

≡Vitamin A

40% — air/light-sensitive (fat-soluble)

≡Vitamin B12

10% — relatively heat-stable

≡Thiamin (B1)

80% — heat- and alkali-sensitive

🎉 Correct order! Water-soluble + multi-sensitive (C, B1, B2) lose most; fat-soluble & stable (K, B12) endure best.

⚠ Not quite. Hint: check the 'max cooking loss' column of Table 8.1 — water-soluble and heat/air/light-sensitive lose the most.

8.6 Causes of loss

Where do vitamins go?

🌱

Inherent variation

Cultivar, maturity, site, climate (tomato vitamin C varies with ripeness).

✂️

Postharvest / prep

Enzymes (ascorbate oxidase, lipoxygenase), trimming & peeling.

💧

Leaching

Water-soluble vitamins dissolve into wash/blanch/cook water — the biggest route.

🌾

Milling

Bran & germ removed, taking much of the B-group (see chart).

🔥

Thermal

Blanching, sterilization: oxidation + leaching; HTST improves retention.

📦

Storage

Residual O₂, light, time — slow but significant.

Fig 8.1 (representative)

The finer the milling, the more B-vitamins are lost

Bran and germ are rich in B-vitamins. The whiter the flour (lower extraction), the lower the retention.

Lost most: thiamin (B1)
More robust: vitamin E, pantothenate
Hence → enrichment adds B1, B2, niacin, iron and folate back into refined flour.

Representative redraw: nutrient retention vs flour extraction rate (lower = more refined). Thiamin is lost most, vitamin E least — the very rationale for enriching cereals (adding back B1, B2, niacin, iron, folate).

8.6.4 Thermal processing

Thermal loss is first-order: hotter = faster decay

Two loss routes in blanching: oxidation and leaching (heat is secondary).

First-order: C = C₀·e^−kt; higher T → larger k (Arrhenius)

HTST: high temp, short time → less total heat exposure → better retention.
Steam blanching leaches less than hot-water blanching.

Schematic: first-order decay vs heating time; 121°C falls far faster than 100°C. HTST (high-temperature short-time) exploits the 'short time' to spare heat-labile vitamins.

🎮 MINIGAME · CALC#5

A vitamin degrades by first-order kinetics with half-life t½ = 30 min. After 60 min of heating, what is the retention?

Hint: 60 ÷ 30 = 2 half-lives.

✔ Correct: 60 min = 2 half-lives → 100% → 50% → 25%. Each half-life halves what remains — that's first-order.

✗ Rethink: it halves every 30 min. 60 min = two halvings → 100→50→? Answer in %.

8.2 Nutrient addition

Four words for adding nutrients

Since 1998 the U.S. mandates folic acid in enriched cereal grains, markedly cutting neural-tube defects (spina bifida, anencephaly).

↺

Restoration

Add back key nutrients lost in processing, to the original level.

↑

Fortification

Add to make the food a good/superior source — may include nutrients not naturally present.

✓

Enrichment

Add specified amounts per FDA standards of identity (e.g. flour: B1/B2/niacin/iron).

＋

Nutrification

A generic term for any addition of nutrients to food.

🎮 MINIGAME · MCQ#6

Since 1998 the U.S. has mandated which vitamin in enriched cereal grains to reduce neural-tube defects?

✔ Correct: folic acid. The synthetic form is far more stable than natural tetrahydrofolate; the dose is capped to avoid masking B12 deficiency. The policy sharply cut spina bifida and anencephaly.

8.5 / 8.1.3

Bioavailability & toxicity

Bioavailability (8.5)

The fraction actually absorbed + utilized after ingestion. Three factors:

Concentration at the time of consumption
Chemical form of the vitamin
Interactions with the food matrix (protein, fiber, lipid)

Toxicity (8.1.3)

Excess can harm too — especially A, D, B6.

Almost always from supplement overuse, not whole foods.
Also from over-fortification (a vitamin-D milk incident once occurred).
→ Needs ongoing regulatory & public-health monitoring.

8.10 Optimization

Three levers to keep vitamins in the food

You want to maximize retention — which lever first?

↓

① Beat the heat

Shorten hot time

Use HTST; avoid overcooking.

② Beat leaching

Less water, less cut

Steam not boil; cook whole; reuse the broth.

③ Beat O₂/light

Exclude O₂ & light

O₂-barrier & opaque packaging; add antioxidants.

Stable ≠ retained: chemistry decides

Every vitamin has its weakness — heat, light, oxygen, alkali, or simply water. Read Table 8.1 and you can predict what processing will do, and design the highest-retention process.

A·D·E·K

Fat-sol: stored·oxidize·toxic

C·B

Water-sol: leach·daily

100%

C/folate max cooking loss

HTST

high-temp short-time

Self-check: can I tell fat- from water-soluble, name 3 loss routes, and use Table 8.1 to predict which vitamin to worry about most?