Analysis of sweet potato (Ipomoea batatas) from the highlands of Papua New Guinea: relevance to the incidence of Enteritis necroticans

Abstract

Analyses have been made for crude protein, amino acids, and trypsin inhibitor content of 21 cultivars of sweet potato collected from two regions of the highlands of Papua New Guinea, one (Upper Mendi region) of high incidence of Enteritis necroticans (EN) and the other (Erave region) of low incidence of EN. The incidence of EN occurs in populations that are reported to be low in protein; hence, the analysis of the staple food (sweet potato) may give a clue to the difference between the two regions. No significant differences were found in the crude protein content, amino acid scores, or trypsin inhibitor contents between the sweet potatoes from the two regions. The range of crude protein content is 0.5-2 g of protein/100 g of fresh sweet potato; the S-containing amino acids (cystine plus methionine) are limiting in 65% of cases, followed by lysine (23%), leucine (6%), and other amino acids. The average chemical score is 0.6. The trypsin inhibitor content varies greatly over a 67-fold range. No significant correlation (r = 0.057) is found between trypsin inhibitor and crude protein.

Nutritional Quality of Sweetpotato Greens from Greenhouse Plants

“…Aliqouts (0.1-0.2 ml) were assayed by a spectrophometric method (AOAC 952.03) modified by reducing reagent volumes to 1/10 the original values. Trypsin and chymotrypsin inhibitors were extracted from the leaves (2.0 g per 15 ml buffer) and assayed by inhibition of the enzyme action on the synthetic substrates ptosyl-L-arginine methyl ester and N-benzoyl-L-tyrosine ethyl ester, respectively (Bradbury and Holloway, 1988;Bradbury et al, 1984 and.…”

Biomass yield and composition of sweetpotato grown in a nutrient film technique system

“…Aliqouts (0.1-0.2 ml) were assayed by a spectrophometric method (AOAC 952.03) [13] modified by reducing reagent volumes to 1/10 the original values. Trypsin and chymotrypsin inhibitors were extracted (2.0 g per 15 ml buffer) and assayed by inhibition of the enzyme action on the synthetic substrates p-tosyl-L-arginine methyl ester and N-benzoyl-Ltyrosine ethyl ester, respectively [16][17][18].…”

Distribution of proteinases and carbohydrases in the midgut of larvae of the sweetpotato weevil Cylas formicarius elegantulus and response of proteinases to inhibitors from sweet potato

“…Extraction of Ipomoea batatas. Lyophilized samples ofL batatas equivalent to 40.0 g(fresh wt) were extracted with 120 ml 50 mM tris-chloride pH 8.0 containing 10 mM CaC12 according to Bradbury et al (1984). Two samples of each following variety or cultivar were extracted: Jewel, Centennial, J5/485, I / 11-70, and 82 / 88.…”

“…A possible source of resistance in L batatas is the presence of trypsin inhibitors in roots (Sohonie & Bhandarkar, 1954;Sohonie & Honawar, 1956;Sugiura et al, 1973). The trypsin inhibitors have been studied in relation to human health (Bradbury et al, 1983(Bradbury et al, , 1984 but little is known of possible deleterious effects of the inhibitors on C. f elegantulus. Since naturally occurring proteinase an6 amylase inhibitors have been implicated as resistance factors against insects (Gatehouse et al, 1979;Yetter et al, 1979), the presence and distribution of selected digestive enzymes within the larval midgut were studied and effects of extracts prepared from several cultivars of L batatas on activity of both bovine pancreatic trypsin and midgut proteinases from C. f elegantulus were determined.…”