All Quinnoa articles in one place.
Hard, aged cheeses are usually the lowest in lactose. Analytical reviews place Parmigiano Reggiano, Grana Padano and Pecorino Romano below 0.01 g/100 g, with Emmental, Gruyère and some blue cheeses below 0.1 g/100 g. Actual content varies by process and brand, and lactose intolerance is not the same as milk-protein allergy.
Opened shredded cheese should stay at 40 °F or below, and the package's after-opening direction is the most specific guide. FoodKeeper gives about 1 month as a broad refrigerated reference for shredded cheese, but some manufacturers recommend a much shorter period after opening. If mold appears in shredded cheese, discard the whole package.
Many aged cheeses naturally develop white or crunchy crystals. Two common types are calcium lactate and the amino acid tyrosine; they can form on the surface or inside the cheese and are not, by themselves, signs of spoilage.
There is no single storage time for every cheese. USDA gives about 3–4 weeks after opening for hard cheeses such as cheddar, Swiss and Parmesan, while soft cheeses such as cottage cheese, ricotta or Brie are generally around 1 week. A shorter package instruction should take priority.
Fresh cheese should stay refrigerated and the package's use-by and after-opening directions should come first. As a broad reference, USDA gives about 1 week in the refrigerator for several soft cheeses at 40 °F or below, but individual fresh cheeses may carry a shorter after-opening instruction.
A hard edge on refrigerated cheese is usually a moisture problem, not the refrigerator somehow cooking it. Exposed cheese loses water to the surrounding air, concentrating the protein-and-fat matrix at the surface. Protecting the cut face slows that drying.
The shiny oil on melted cheese is milk fat that has separated from the protein matrix. Melting is not simply turning a solid into a liquid: casein has to soften while still holding water and liquid fat. When that balance breaks, free oil collects on the surface.
Flaking is built into fish muscle structure. As fish cooks, its proteins coagulate and the collagen between muscle segments softens, allowing those segments to separate along natural lines. Overcooking and repeated handling then make an already delicate fillet much easier to break.
The problem is not that rice automatically becomes dangerous the next day. Bacillus cereus spores can survive cooking; if cooked rice spends too long at room temperature, they can germinate, multiply, and produce toxin that later reheating may not destroy.
Large, long-lived predators accumulate the most methylmercury. FDA/EPA's Choices to Avoid are king mackerel, marlin, orange roughy, shark, swordfish, Gulf of Mexico tilefish, and bigeye tuna for people who are pregnant or breastfeeding and for young children.
Cooking does not create fish odor from nothing: heat helps volatile molecules enter the air. Trimethylamine is one of the characteristic compounds that increases as many marine fish lose freshness, so a strong off-odor before cooking is more concerning than aroma that becomes obvious only once the pan is hot.
Freshness is a major reason one hard-cooked egg peels cleanly while another loses chunks of white. USDA says albumen rises from about pH 7.4 in a newly laid egg toward about pH 9 as it ages, reducing its attraction to the shell membrane.