Monosodium glutamate msg

The combination of three tastants was infused in the duodenum, the ileum, or both the duodenum and the ileum. In order to prevent side effects from occurring, 75% of acceptable daily intake (ADI) of these tastants was infused. 540 mg Rebaudioside A (Reb A, Stevija Natuurlijk, Drachten, The Netherlands), 75 mg Quinine (Arnold Suhr, Hilversum, The Netherlands), and 2 g Monosodium Glutamate (MSG, Ajinomoto, Hamburg, Germany) were dissolved in 120 mL tap water and was used as tastant mixture for infusion, as was done by van Avesaat et al. [18 (link)]. All tastants used were non-caloric and yielded no nutritional value. The placebo infusion consisted of 120 mL of tap water. A magnetic stirrer was used to dissolve the tastants. The mixture was infused over a 60-min period with an infusion rate of 2 mL/min. This was consistent with the infusion rate of van Avesaat et al. mimicking the slow influx from the stomach to duodenum and slow transit through the gut in the ileum.

The objective was to obtain a gel flavour similar to that of the concentrate alone. A series of internal tastings enabled the formulation of xanthan gels made with protein concentrates which was adapted from [42 (link),43 (link)]. A total of 20 g of crude (P) or heated (HP) protein concentrate and 1.0 g of xanthan gum (Texturas, Barcelona, Spain) were mixed (Thermomix TM 5, Vorwerk, Cloyes-sur-le-Loire, France) with 79 g of water (Evian, France) to make a gel at ambient temperature (20 °C). Then, 0.6 g of monosodium glutamate (MSG, 99% pure; Ajinomoto, Tokyo, Japan) was added to the gel to make the flavour more similar to that of the protein concentrate (Figure S1, see Supplementary Materials). For some gels, 0.25% chloride sodium salt (NaCl, Saline Cerebos, Levallois-Perret, France) and/or 3% deodorised sunflower oil (Cœur de Tournesol, Lessieur, Asnière-sur-Seine, France) were added to the previous mix. For all gels, the mixing speed was 500 rpm for 10 min. The different formulations resulted in 12 different samples (Table 1). The samples were stored at −20 °C after formulation and defrosted at 4 °C one day before serving.

Commercially available food additive products were used in the human sensory test. Food-grade NaCl was purchased from Naikaisyoji (Tokyo, Japan), and monosodium glutamate (MSG) was purchased from Ajinomoto Co., Inc. (Tokyo, Japan). All flavor compounds (of food additive grade), including propionaldehyde, butanal, isobutylaldehyde, 2-methylbutylaldehyde, pentanal, IVA, hexanal, heptanal, octanal, propionic acid, 2-methylbutyric acid, isovaleric acid, hexanoic acid, heptanoic acid, propyl alcohol, 2-methyl-1-butanol, hexanol, heptanol, methional, methionol, and 3-(methiylthiol) propionic acid, were purchased from Sigma-Aldrich (St. Louis. MO, USA). Deionized water for test solutions and mouth rinsing was supplied by a Mill-Q water purification system (Millipore, Bedford, MA, USA). γ-Glu-Val-Gly was obtained from Ajinomoto Co., Inc. (Tokyo, Japan). NPS-2143, a CaSR inhibitor, was synthesized, as described by Rybczynska et al. [41 (link)]. Chemicals for cell based-assays, such as CaCl₂, ethylenediaminetetraacetic acid (EDTA), and probenecid, were purchased from Sigma-Aldrich (St. Louis. MO, USA).