Most studies have been carried out on the relative reactivities of free amino acids. For
example, Kroh & Westphal (1989) found that basic amino acids are more reactive than
neutral or acid amino acids. Ashor & Zent (1984) suggested a classification of amino
acids into three groups depending on the extent of browning when reacted with glucose
at different pH, and 121 oC for 10 minutes. The most reactive were lysine, glycine,
tryptophan and tyrosine. These results should be of applicability to candy because this
is a typical processing range. Other results show that comparisons can only be used if
the same pH and buffering conditions are used. For example, the effect of pH is
especially significant due to the different pKa values of the amino acids. Lysine appears
to be the most reactive amino acid (Ashor & Zent, 1984; O’Brien & Massey, 1989) due
to the fact that is has two available amino groups. However, the reactivity of lysine
would appear to be dependent on the conditions of the reaction being studied.
Most studies have been carried out on the relative reactivities of free amino acids. Forexample, Kroh & Westphal (1989) found that basic amino acids are more reactive thanneutral or acid amino acids. Ashor & Zent (1984) suggested a classification of aminoacids into three groups depending on the extent of browning when reacted with glucoseat different pH, and 121 oC for 10 minutes. The most reactive were lysine, glycine,tryptophan and tyrosine. These results should be of applicability to candy because thisis a typical processing range. Other results show that comparisons can only be used ifthe same pH and buffering conditions are used. For example, the effect of pH isespecially significant due to the different pKa values of the amino acids. Lysine appearsto be the most reactive amino acid (Ashor & Zent, 1984; O’Brien & Massey, 1989) dueto the fact that is has two available amino groups. However, the reactivity of lysinewould appear to be dependent on the conditions of the reaction being studied.
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