Quantities and qualities of leaf protein concentrates from wild species and crop species grown under controlled conditions

Abstract

The amount of protein produced per m2 by plants cultivated in soil in a greenhouse at three levels of fertilizer application, for c. 10 weeks, was estimated by Kjeldahl analysis of the TCA-insoluble fraction of freeze-dried material. The quantity of protein extractable for production of leaf protein concentrates was determined by Kjeldahl analysis of non-dried but frozen material after disintegration with a meat mincer and an Ultra-Turrax homogenizer, hydraulic pressing and filtration, and protein precipitation by heat (in two steps) or by TCA. The precipitability was also studied by Folin-Ciocalteu determination of protein. The quality of each protein concentrate was studied by determining nitrogen content (Kjeldahl), digestibility by pepsin and by pepsin+ pancreatin, nutritive value in Tetrahymena tests, and lysine and methionine content (analysed microbiologically).Twenty-nine species and varieties were investigated. Large differences between species were found in all the properties studied. Protein extractability varied between 5 and 80%, while the extractable protein produced per m2 ranged between I and 140 g. The highest digestibility was two to three times greater than the lowest one. In the most digestible species (Amaranthus caudatus), 82% of the N of the chloroplastic protein concentrate was digested by pepsin +pancreatin. The Tetrahymena value generally ranged between 40 and 98, whereas casein gave values of about 75. The lysine content always exceeded the FA0 minimum. The methionine content of most species varied between 2.0 and 2.2% of the hydrolyzed protein.Amaranthus caudatus and the Chenopodiaceae investigated were the most suitable species for large-scale production of leaf protein concentrates for human consumption because they gave high yield of extractable protein and high-quality protein concentrates.

Feed protein fractions in various solvents of ruminant feedstuffs

“…These data are in agreement with results by Wall et al (1975), Sozinov (1985) and Ganesh and Grieve (1990). McDonald (1982) reported that the content of NPN in red clover leaves and stems was 13É8 and 37É4% of total N, respectively, while Lexander et al (1970) found that the NPN was between 3É7 and 32É5% of the protein N over a wide range of forage plants. They concluded that nitrogenous fertilisers increased the NPN content of both grasses and legumes.…”

Seasonal respiration of foliage, fine roots, and woody tissues in relation to growth, tissue N, and photosynthesis

“…1998). N and respiration may be related because most of N is in protein (Lexander et al . 1970), which requires maintenance respiration for repair and replacement (Ryan 1991).…”

“…One hypothesis proposed to explain differences in maintenance respiration is that tissue N varies within and between tissues (Ryan 1991). In this model, N is used as an easily measured surrogate for protein concentration because most of the nitrogen in plant cells is associated with protein (Lexander et al . 1970).…”

“…One hypothesis proposed to explain differences in maintenance respiration is that tissue N varies within and between tissues (Ryan 1991). In this model, N is used as an easily measured surrogate for protein concentration because most of the nitrogen in plant cells is associated with protein (Lexander et al 1970). Maintenance respiration and protein are linked because maintenance respiration may support protein repair and replacement (Penning de Vries 1975; but see Bouma et al 1994), and because other maintenance processes such as ion transport may be correlated with protein content.…”

NUTRITIVE VALUE OF LEAF PROTEIN CONCENTRATES PREPARED FROM Amaranthus SPECIES

“…amounts of extractable protein (Lexander et al 1970 Pedersen and Wang (197 l), have been detected inAmaranthus foliage at high levels (Cheeke, unpubl. observ.).…”