KEEPING-QUALITY ASSESSMENT OF PASTEURIZED MILK BY MULTIVARIATE-ANALYSIS OF DYNAMIC HEADSPACE GAS-CHROMATOGRAPHIC DATA .1. SHELF-LIFE PREDICTION BY PRINCIPAL COMPONENT REGRESSION
B. Vallejocordoba et S. Nakai, KEEPING-QUALITY ASSESSMENT OF PASTEURIZED MILK BY MULTIVARIATE-ANALYSIS OF DYNAMIC HEADSPACE GAS-CHROMATOGRAPHIC DATA .1. SHELF-LIFE PREDICTION BY PRINCIPAL COMPONENT REGRESSION, Journal of agricultural and food chemistry, 42(4), 1994, pp. 989-993
An objective and rapid analytical system for milk shelf-life predictio
n was established. Volatiles as determined by dynamic headspace capill
ary gas chromatography (DH-GC), psychrotrophic bacterial counts, and s
ensory evaluation were monitored during refrigerated storage of pasteu
rized milk. High correlation between flavor-related shelf life and vol
atiles indicated that a good proportion of the total variation was exp
lained by the mathematical model obtained by principal component regre
ssion (PCR). The resulting standard error of the estimate of less than
2 days was an excellent approximation in shelf-life studies. Using DH
-GC, results are available in 20 h (18 h of preliminary incubation + 2
h of detection and data processing). Although other rapid instrumenta
l techniques have been proposed, they are indirectly related to flavor
-related shelf life. Milk quality deterioration and consequently the t
ermination of shelf life are caused by the appearance of off-flavors m
ainly determined by a composite effect of spoilage volatiles. Therefor
e, multivariate interpretation of headspace gas chromatographic data a
nd flavor-related shelf life as derived by PCR offers a direct and acc
urate approach to milk shelf-life prediction.