Total Protein and Amino acid Compositions in the Acorns of Turkish Quercus L. Taxa

Abstract

Total protein content and level of 14 amino acid in mature acorns of 20 Quercus taxa from Turkey were studied. The range of total protein amounts between 2.75 and 8.44% were detected among taxa. Similar values in related species and variety level were observed. The amino acid profiles for each taxon were characteristically different and high variability of individual amino acid concentration was present at variety, subspecies and species levels. Different amino acid concentrations, relative percentages and critical values of some amino acids are thought to be additional considerable parameters for diagnosis of Quercus. Generally higher total quantity of amino acids in section Quercus and lower values in section Ilex were observed. When the essential and non-essential amino acids are expressed as a relative percent of total protein indicating quality of proteins, the ratios varied significantly among taxa (p < 0.05). But, no significant difference at section level were detected. Major amino acids were aspartic acid and glutamic acid showing the largest variations and the lowest levels were detected for methionine. Amino acid concentrations ranged from 1665 for aspartic acid to 13 mg/100 g dry wt. for methionine. All taxa had relatively higher amounts of leucin, lysin and valine than other essential amino acids. The highest quantity of protein and amino acids was recorded for Q. infectoria ssp. boissieri and the lowest for Q. pontica. The level of all essential amino acids in examined taxa was not sufficient compared to FAO scoring pattern for children (1985). But, threonine and valine in Q. infectoria ssp. boissieri and isoleucine in Q. petraea ssp. iberica show remarkable concentrations to the requirements. All examined essential amino acids among taxa generally provide adequate levels for adults according to FAO standard.

Characterization of Acorn Fruit Oils Extracted from Selected Mediterranean Quercus Species

“…This result agrees with the results reported by (Özcan, 2006 andLopes et al, 2005) who found that the oil content of some species of acorn ranged between 3.8 and 9.1%. This indicates that the oil content of these acorn species is low for commercial production as cooking or frying oils.…”

Epicuticular waxes and plant primary metabolites on the surfaces of juvenile Eucalyptus globulus and E. nitens (Myrtaceae) leaves

“…This is not to say that the internal and even leaf surface composition of plant primary metabolites cannot be genotype-specific (see Yeoh et al 1984;Soldaat et al 1996;Özcan 2006). Plant secondary metabolites are thought to determine host specificity through their tendencies to be perceived at distance from the source (cf.…”

The influence of acorn flour on rheological properties of gluten-free dough and physical characteristics of the bread

“…Due to high variability of genus, Quercus acorns differ in chemical composition, depending on the species. It could be generally said that 31-55 % of their mass is composed by starch, 2.75-8.44 % protein (with advantageous amino acid composition, and high content of essential amino acids, proper especially for adults), 0.7-9 % fat (although in some species of Quercus Erthrobalanus spp., i.e., black and red oak group, it may exceed 31 %) [11,[15][16][17]. Oil present in acorns has a taste comparable to olive oil and contains high levels of unsaturated fatty acids (even above 80 %), mostly oleic and linoleic acids, 10.2-65 % and 17.6-49.1 %, respectively [15,18].…”