Maillard reactions: do the properties of liquid matrices matter

The amounts of browning due to the interaction of lysine and xylose occurring when these reactants were in different liquids have been investigated. The reactants were suspended/solvated in water, corn oil, glycerol, different propylene gylcols and mixtures of these liquids. In water the amount of browning was found to equate to the concentration of the reactants to the third power. In glycerol and polypropylene glycol 76 ° the amount of browning was higher than that achieved for the same amount of reactants in water. In corn oil and polypropylene glycol 1200 no browning was observed. In all samples the addition of water to another liquid caused the level of browning to be increased, until a maximum was achieved. This maximum may have corresponded to the point where all the reactants were soluble in the matrix. Further addition of water decreased the amount of browning. In all cases the amount of browning seemed to relate to the concentration of the reactants if they were calculated as just occurring in the water portion of the matrix. Values calculated in this way were significantly, but constantly a little lower than the experimental results in all cases except for the corn oil, where the values directly corresponded. The predictability of these values was surprising considering that the matrices gave miscible and phase-separated systems.