01
Glutamates
Glutamic acid, monosodium glutamate and other glutamate salts form one cluster in the directory. The shared root does not make the entries identical.
E-number field guide
Flavour enhancers, properly explained.
A researched guide to what this category means on a UK label, the important subtypes, and all 20 entries in NutraSafe’s published library.
Example UK ingredients-list format
Flavour enhancer: E621
Monosodium glutamate20library entries
3key distinctions
4primary sources
The plain-English answer
What flavour enhancers actually do
Flavour enhancers strengthen or round out tastes already present in a food. They are different from flavourings, which add a flavour of their own, although the distinction is easy to miss in a long ingredients list.
This directory covers the flavour-enhancer records in our published database. Each code links to a full page with its own research, regulatory notes and source list.
Know the differences
One category. Several very different jobs.
The exact code matters more than the category headline. These are the distinctions that make the list easier to read without turning every additive into the same story.
02
Guanylates and inosinates
These nucleotide-related enhancers appear as acids, individual salts and combined ribonucleotides. Products may use them alongside glutamates, but the exact code identifies which form is present.
03
Function is not the same as flavour
A flavour enhancer strengthens taste or odour already present; a flavouring adds or modifies flavour. That distinction explains why a label may use one term rather than the other.
A better way to read the packet
Function first, then the exact name
1
Find the function
UK guidance says the ingredients list identifies what the additive does, such as “preservative” or “antioxidant”.
2
Read the name or E-number
The specific substance can follow as a name or code. Both routes identify the additive; neither is a safety score.
3
Open the individual entry
That is where NutraSafe separates source, uses, current regulatory detail, research notes and citations for that code.
Current GB context: since 1 April 2025, the FSA’s electronic register has been the official public list of authorised food additives in Great Britain. An authorisation can include food-category limits and notes, so appearing in a directory does not mean unrestricted use in every food. Read the register guidance.
All flavour enhancers
Showing all 20
Free glutamate activates taste receptors on the tongue that register umami, the fifth basic taste alongside sweet, sour, salty and bitter.
Read the full entryAdds umami, the savoury 'fifth taste'.
Read the full entryIt releases glutamate ions in the mouth, stimulating umami taste receptors (the same receptors activated by MSG).
Read the full entryGlutamate activates umami taste receptors on the tongue (the T1R1/T1R3 receptor complex and metabotropic glutamate receptors), producing the savoury, mouth-filling quality described as umami, the fifth basic taste alongside sweet, sour, salty and bitter.
Read the full entryFree glutamate activates taste receptors on the tongue that respond to umami, the fifth basic taste associated with savoury, meat-like depth.
Read the full entryGlutamate activates umami taste receptors on the tongue, amplifying the perception of savoury, meaty, or brothy flavour.
Read the full entryGMP binds to umami taste receptors on the tongue and dramatically amplifies the savoury signal, particularly when combined with glutamates such as monosodium glutamate (E621).
Read the full entryGuanylate acts on the same umami taste receptors as glutamates, binding to the T1R1/T1R3 receptor complex on the tongue.
Read the full entryGMP is a nucleotide that binds to umami taste receptors (the T1R1/T1R3 heterodimer on the tongue) and dramatically amplifies the umami signal produced by glutamates such as monosodium glutamate (MSG, E621).
Read the full entryGuanylates bind to umami taste receptors on the tongue and dramatically amplify the perceived savoury intensity of food, particularly when combined with glutamates such as E621 (MSG).
Read the full entryInosinic acid activates umami taste receptors (specifically the T1R1/T1R3 heterodimer) on the tongue.
Read the full entryInosinate enhances and prolongs the perception of umami (savoury depth) by binding to taste receptors on the tongue that are already activated by glutamate.
Read the full entryIMP is a potent umami synergist.
Read the full entryInosinate salts act as flavour synergists rather than flavours in their own right.
Read the full entryNucleotides like inosinate and guanylate bind to the same taste receptors on the tongue that glutamate activates.
Read the full entryE635 enhances the perception of umami, the savoury fifth taste.
Read the full entryGlycine acts as a flavour enhancer by contributing a mild, slightly sweet taste with a subtle savoury note.
Read the full entryAs a flavour enhancer, L-leucine contributes a mildly bitter taste characteristic that can round out or intensify savoury profiles in combination with other flavour compounds.
Read the full entryAs a flavour enhancer, it intensifies savoury and umami taste notes in a similar manner to monosodium glutamate, though it is less potent.
Read the full entryIt dissolves flavouring compounds and helps distribute them evenly throughout a food product.
Read the full entryNo matching additive in this category.
Questions, answered
What people usually want to know
Is a flavour enhancer the same as a flavouring?
No. The legal class covers substances that enhance an existing taste or odour. Flavourings are regulated separately and are used to give or modify flavour.
Is MSG the only flavour enhancer?
No. MSG is E621, but the directory also includes other glutamates, guanylates, inosinates and combined ribonucleotides.
Why do some products use more than one enhancer?
Different enhancers can be used together for a particular recipe effect. The ingredients list should identify each additive used.
How this guide was checked
Primary sources, not filler
The category explanation and label rules above were checked against official UK guidance, the GB authorisations register, legislation and EFSA background material. Individual additive pages carry the sources for their additive-specific claims.
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Directory updated: 16 September 2026