Growth Performance of Rats Fed Jojoba Proteins. Possible Correlations with Trypsin Inhibitory Activity in Jojoba Proteins

Abstract

The effects of the water-soluble protein fraction of jojoba meal on growth and relative organ weight in rats were tested. Trypsin inhibitory activity (TIA) was measured in the untreated water-soluble jojoba proteins and in preparations after dry-heating (100 °C, 2 h) or methanol extraction (Soxhlet, 6 h). TIA was found in the jojoba protein fraction and could not be destroyed by dry-heating or methanol extraction of the jojoba proteins. In the first feeding experiment, growth performance and relative organ weight were compared of young rats fed ad libitum a diet containing either 18% soybean proteins (C), 6% soybean proteins (P6), or 6% soybean proteins supplemented with 12% jojoba proteins (JJ) or 12% toasted jojoba proteins (JJT). In a second 3 week experiment, growth and relative organ weight of young rats receiving a diet containing 6% soybean proteins supplemented with 12% methanol-extracted jojoba proteins (JJM) were compared for rats pair-fed with JJM with a diet containing 18% soybean proteins (PF). Although food intakes of C, JJ, and JJT rats were similar and P6 rats ate more than C rats, P6, JJ, and JJT rats showed growth retardation compared to C rats. JJM rats and PF rats showed a similar growth. The pancreas was hypertrophied in JJ and JJT rats, compared to C rats, and in JJM rats, compared to PF rats. Interscapular brown adipose tissue (BAT) was hypertrophied in P6, JJ, and JJT rats but normal in the JJM group. Jojoba proteins induce growth retardation. This is accompanied by pancreatic and BAT hypertrophy. As trypsin inhibition does not change but growth does ameliorate and BAT hypertrophy is abolished after methanol extraction, trypsin inhibition has no major influence on growth in the present experiments, while BAT hypertrophy is accompanied by growth reduction. Keywords: Simmondsia chinensis; jojoba meal; jojoba protein concentrate; rat