How foods are produced, processed, fermented, cured and manufactured, and what those processes change.
Fermentation and pickling can both create sour foods, but they do it differently. Fermentation relies on microorganisms to convert sugars into acids. Quick pickling adds acid, usually vinegar, from the start. A fermented cucumber can be both pickled and fermented; a vinegar pickle may never ferment.
Kombucha is made by fermenting sweetened tea with a community of bacteria and yeasts, often associated with a cellulose pellicle called a SCOBY. Some sugar is converted into organic acids, carbon dioxide, and small amounts of alcohol, but the final composition varies widely.
Kimchi and sauerkraut share lactic-acid fermentation, but they are not the same food. Traditional sauerkraut is mainly cabbage and salt. Kimchi usually adds napa cabbage, radish, garlic, ginger, scallions, and chile, creating a different flavor and micronutrient profile.
Kefir is a fermented milk drink made with a mixed community of bacteria and yeasts traditionally housed in kefir grains. During fermentation some lactose is converted into lactic acid and other compounds, while milk protein, calcium, and many micronutrients remain.
Milk kefir and water kefir both rely on communities of bacteria and yeasts, but they are not nutritionally interchangeable. Milk kefir starts with milk and keeps much of its protein and calcium. Water kefir starts with sweetened water, so its final composition depends heavily on the recipe and how far fermentation proceeds.
Plain yogurt and milk kefir are nutritionally more alike than social media sometimes suggests. When made from similar milk, both provide comparable protein, calcium, and fat. The bigger difference is fermentation: yogurt uses defined bacterial cultures, while traditional kefir combines lactic-acid bacteria, other bacteria, and yeasts.
Sourdough fermentation creates real biochemical differences, including organic acids and phytate breakdown. Those effects can matter, but a white sourdough does not acquire the fiber of whole-grain bread simply because it was fermented longer.
Packaging matters because olive oil ages faster with light and oxygen. Dark glass gives an excellent oxygen barrier and reduces light exposure; a properly coated metal tin is opaque and also provides a strong oxygen barrier. PET is lightweight and convenient but generally allows more oxygen transmission and, when clear, little light protection. Storage location and bottle size still matter.
The maza is generally the most tender and juicy part of a whole Spanish ham. It contains the largest mass of meat and usually more intramuscular fat. The narrower contramaza and babilla tend to cure more intensely and feel firmer, while the punta is rich and fatty and the shank areas are more fibrous.
On EU-regulated olive-oil labels, “cold extraction” has a specific meaning: virgin or extra-virgin olive oil obtained by percolation or centrifugation of olive paste below 27°C (80.6°F). It does not mean the olives were never warmed, and it does not by itself guarantee better flavor. It describes extraction temperature and method.
Olive-oil acidity is a laboratory measure of free fatty acids, conventionally expressed as grams of oleic acid per 100 g of oil. It is not pH and it does not directly measure sourness. Under international and EU standards, extra-virgin olive oil has a maximum free acidity of 0.8 g/100 g; virgin olive oil can be up to 2 g/100 g.
Spain's Iberian-ham seal colors are legally defined. Black means acorn-fed 100% Iberian; red means acorn-fed Iberian; green means field-fed Iberian; white means feed-fed Iberian. Only black guarantees 100% Iberian genetics from the color alone. On red, green and white products, read the label for the Iberian breed percentage.