Manufacturers add MSG (or free glutamates) to foods as an inexpensive way to impart a savoury / meaty flavour without having to actually put in any (or as much) meat or protein. To help identify this unsavoury additive, here is a comprehensive list of ingredients that contain MSG or free glutamates.
Anything with “glutamate” or “glutamic acid” in its name
Magnesium glutamate (E625, Magnesium diglutamate, Magnesium di-L-glutamate)
Monoammonium glutamate (E624, Monoammonium L-glutamate)
Monopotassium glutamate (E622)
Monosodium glutamate (E621, MSG, UNII-W81N5U6R6U) (Brand names: Aji-no-moto, Ve-tsin, Tasting Powder, Sazón, Accent)
Monosodium glutamate monohydrate (MSG monohydrate)
Monosodium L-glutamate monohydrate
Sodium glutamate monohydrate
Sodium cocoyl glutamate
Glutamic acid (E620, L-Glutamic acid, Glutamate)
Calcium glutamate (E623)
Natrium glutamate
Anything that is hydrolyzed or autolyzed
Autolyzed yeast
Autolyzed yeast extract
Autolyzed yeast protein
Autolyzed plant protein
Hydrolyzed beef stock
Hydrolyzed collagen
Hydrolyzed corn
Hydrolyzed corn gluten
Hydrolyzed corn protein concentrate
Hydrolyzed cornstarch
Hydrolyzed gelatin
Hydrolyzed guar gum
Hydrolyzed milk protein (Hydrolyzed casein)
Hydrolyzed oat flour
Hydrolyzed plant protein (HPP)
Hydrolyzed protein
Hydrolyzed soy protein
Hydrolyzed soybean
Hydrolyzed soybean oil
Hydrolyzed vegetable broth
Hydrolyzed vegetable protein (HVP)
Hydrolyzed wheat
Hydrolyzed wheat gluten
Hydrolyzed whey protein
Hydrolyzed whey protein concentrate
Hydrolyzed whey peptides
Hydrolyzed yeast (Hydrolyzed brewer’s yeast, Hydrolyzed torula)
Calcium caseinate
Sodium caseinate
Any protein isolate
Soy isolate
Soy protein isolate
Wheat protein isolate
Whey protein isolate
Protein isolate
MSG synergists and glutamate-creating enzymes
Disodium guanylate (E627, GMP)
Disodium inosinate (E631, IMP)
Disodium 5′-ribonucleotides (E635)
Glutaminase (enzyme that converts glutamine to glutamate)
Typically high in MSG or free glutamates
Ac’cent® Flavor Enhancer
Anchovy paste
Bouillon
Brewer’s yeast
Broth
Coconut aminos
Dashi (Seaweed stock, Kombu dashi)
Fish sauce
Fish extract
Hoisin sauce
Liquid aminos
Matured cheeses (e.g. Parmesan, Roquefort)
Meat extract
Miso (Miso paste)
Mushroom extract (Mushroom concentrate)
Natto
Nutritional yeast
Oyster sauce
Plant protein extract
Seaweed extract (Tangle extract, Kombu extract)
Shrimp paste
Soy extract (Soy sauce extract)
Soya sauce (Soy sauce)
Soybean paste (Doenjang)
Stock
Tomato concentrate
Torula yeast
Umami paste
Vegetable extract
Worcestershire sauce
Yeast extract (Vegemite, Marmite)
Yeast food
Yeast nutrient
May contain free glutamates
Carrageenan (E407)
Gelatin
Malt flavoring
Malt extract
Malted barley (Barley malt)
Natural beef flavoring (Beef flavor)
Natural chicken flavoring (Chicken flavor)
Natural flavoring (Natural flavor)
Natural pork flavoring (Pork flavor)
Soy protein
Soy protein concentrate
Textured protein
Textured vegetable protein (TVP)
Whey protein
Whey protein concentrate
Zinc proteinate
(The above list is based on dozens of sources. Please let me know if you notice any mistakes or omissions. Thank you!)