Onigiri Tuna

Succinic acid () is a dicarboxylic acid with the chemical formula (CH2)2(CO2H)2. The name derives from Latin succinum, meaning amber. In living organisms, succinic acid takes the form of an anion, succinate, which has multiple biological roles as a metabolic intermediate being converted into fumarate by the enzyme succinate dehydrogenase in complex 2 of the electron transport chain which is involved in making ATP, and as a signaling molecule reflecting the cellular metabolic state. Succinate is generated in mitochondria via the tricarboxylic acid cycle (TCA), an energy-yielding process shared by all organisms. Succinate can exit the mitochondrial matrix and function in the cytoplasm as well as the extracellular space, changing gene expression patterns, modulating epigenetic landscape or demonstrating hormone-like signaling. As such, succinate links cellular metabolism, especially ATP formation, to the regulation of cellular function. Dysregulation of succinate synthesis, and therefore ATP synthesis, happens in some genetic mitochondrial diseases, such as Leigh syndrome, and Melas syndrome, and degradation can lead to pathological conditions, such as malignant transformation, inflammation and tissue injury.

Monosodium glutamate (MSG), or E621, is the sodium salt of glutamic acid, an amino acid found naturally in many foods.

It is widely used as a flavor enhancer to provide an "umami" or savory taste to a variety of processed foods, including soups, snack chips, and frozen meals.

MSG is generally recognized as safe (GRAS) by food authorities. However, some people report sensitivity to MSG, experiencing short-term symptoms like headaches and flushing, though scientific studies have not shown a consistent link.

Disodium inosinate (E631) is the disodium salt of inosinic acid with the chemical formula C10H11N4Na2O8P. It is used as a food additive and often found in instant noodles, potato chips, and a variety of other snacks. Although it can be obtained from bacterial fermentation of sugars, it is often commercially prepared from animal sources.