A simple, reliable, rapid and accurate method for the determination of L-glutamate (MSG) in foodstuffs.
INTRODUCTION:
L-Glutamic acid (L-glutamate), one of the 20 common amino acids,
occurs naturally in foods such as cheese, milk, meat, fish, corn,
tomatoes, mushrooms, soybean and sugar beet. In its free form,
L-glutamic acid is the major flavour enhancing component of foods
with a meaty/savoury taste. The role played by L-glutamic acid in
the palatability of foods is exploited by either traditional cooking
methods that release free L-glutamic acid, or by supplementation
with monosodium glutamate (MSG). Excessive use of MSG as a
food additive (E621) in processed foods results in the symptoms of
“Chinese Restaurant Syndrome” (CRS), where palpitations, severe
headaches, nausea, wheezing and increased body temperature are
thought to result from the neuro-excitory properties of free
L-glutamic acid. Onset of CRS is fast, only 30-60 min after ingestion,
and symptoms generally subside after approximately 2-3 hours.
Around 15% of Americans are sensitive to MSG.
KITS:
Kits suitable for performing 60 assays in manual format (or 700 assays
in auto-analyser format or 600 assays in microplate format) are available
from Megazyme. The kits contain the full assay method plus:
Bottle 1: Buffer (35 mL, pH 8.6) plus sodium azide (0.02% w/v)
as a preservative.
Stable for > 2 years at 4°C.
Bottle 2: (x2) NAD+ plus INT.
Stable for > 2 years at 4°C.
Bottle 3: Diaphorase suspension (3.1 mL).
Stable for > 2 years at 4°C.
Bottle 4: Glutamate dehydrogenase solution (3.1 mL).
Stable for > 2 years at -20°C.
Bottle 5: L-Glutamic acid standard solution
(5 mL, 0.10 mg/mL) in 0.02% (w/v) sodium azide.
Stable for > 2 years at 4°C.