TANNIN CONTENT OF KERNELS OF THE BITTER PECAN

F. R. BRISON and R. F. CAIN Respectively, Professor and formerly Associate Professor of A&M College of Texas The so-called bitter pecan (Hicoria aquatica) grows native in the valleys of many of the rivers and small streams of several of the pecan growing states. In Texas, great numbers of the trees grow along the Sulphur, Sabine, San Jacinto, Trinity, Navasota, and parts of the lower Brazos. It has long been known that standard varieties of pecan (H. pecan), such as Success and Stuart, can be topworked on this species-with good results in some cases and poor results in others. The kernels of bitter pecan have a positive bitter taste, and they are also astringent. The bitterness and astringency render them un-appetizing. Corsa (Nut Culture in the U. S., Special Report, U.S.D.A., 1896) wrote that the kernel of the bitter pecan“. . . is bitterer than that of H. minima." There seems to be no record of previous investigation that reports organic compounds that might be associated with the poor taste of the kernels. Analysis for tannin have recently been made in the Department of Horticulture of two samples of bitter pecans that grew in widely separated localities-one from Camp County in northeast Texas, and the other from the Navasota River in Brazos County. Kernels of the Moore variety of pecan were also analyzed for tannin for comparison. All kernels were mature and normally dry. Data presented is an average of duplicate analyses on dry weight basis. The tannin content of shells of both bitter and common pecans was also determined. Results of these analyses are presented in Table 1. TABLE 1 Kind of Sample Where Grown Percent of tannin (Dry weight basis) Bitter Kernels Camp County 17. 5 Bitter Kernels Brazos County 17. 7 Moore Kernels Bell County 0. 68 Bitter Shells Brazos County 8. 6 Evans Shells Bell County 11. 8 These results show that bitter pecan kernels contain roughly 25 times as much tannin as kernels of the Moore variety of ordinary pecans. They also show that tannin content of shells of bitter pecans closely approaches the tannin content of shells of ordinary pecans.