Improving the Mould and Blue-Stain-Resistance of Bamboo through Acidic Hydrolysis

Bamboo is much more easily attacked by fungus compared with wood, resulting in shorter service life and higher loss in storage and transportation. It has been long accepted that the high content of starch and sugars in bamboo is mainly responsible for its low mould resistance. In this paper, acetic acid, propionic acid, oxalic acid, citric acid, and hydrochloric acid were adopted to hydrothermally hydrolyze the starch in bamboo, with the aims to investigate their respective effect on the mould and blue-stain resistance of bamboo, and the optimized citric acid in different concentrations were studied. The starch content, glucose yields, weight loss, and colour changes of solid bamboo caused by the different acidic hydrolysis were also compared. The results indicated that weak acidic hydrolysis treatment was capable of improving mould-resistant of bamboo. The mould resistance increased with the increased concentration of citric acid. Bamboo treated with citric acid in the concentration of 10% could reduce the infected area ranging to 10–17%, the growth rating of which could reach 1 resistance. The content of soluble sugar and starch remained in bamboo decreased significantly from 43 mg/g to 31 mg/g and 46 mg/g to 23 mg/g, respectively, when the citric acid concentration varied from 4% to 10%. Citric acid treatments of 10% also caused a greatest surface colour change and weight loss. The results in this study demonstrated citric acid treatment can effectively reduce the starch grain and soluble sugars content and improve mould resistance of bamboo, which can be attributed to the reduction of starch grain and soluble carbohydrates (such as glucose, fructose, and sucrose, etc.) in bamboo.

Endosperm starch grains of Andropogon, Arthraxon hispidus, and Hyparrhenia rufa (Andropogoneae, Panicoideae, Poaceae)

Background and Aims: Grasses have five different types of endosperm starch grain morphology. Even though there is high diversity within the family, the morphology of the starch grains is generally represented by one or two species. Some genera, such as Andropogon (Andropogoneae), were reported to have at least three types of starch grains. However, most of the reviewed species were transferred to other genera. Therefore, the question whether the genus has one or more types of starch grain morphology remains unanswered. Methods: Between four and eight mature caryopses were removed from specimens deposited in the herbarium IEB for most species, as well as from plants monitored in the field until they had mature caryopses. The caryopses were attached on a plate with a drop of white adhesive Resistol® or resin and then sectioned with a razor blade. Sections were stained with a drop of diluted Lugol´s solution, microscopically observed and photographed at several magnifications. Key results: All Andropogon species observed have only one type of starch grain morphology, the Andropogon-type. In all species the simple starch grains are much more abundant than the compound ones, except in A. tenuispatheus where the ratio is inverted. The other two reviewed species, Arthraxon hispidus and Hyparrhenia rufa have Andropogon-type and Panicum-type starch grains, respectively. Conclusions: It is confirmed that, so far, all Andropogon species observed have one type (Andropogon-type) of endosperm starch grain morphology. There is variation in the size, size distribution and shape of the starch grains among the species. Andropogon gayanus is the only reviewed species with large starch grains reaching 28 µm, whereas those in the other species measure up to 15 µm in diameter.

Developing a Reference Collection for Starch Grain Analysis in Early Neolithic Western Temperate Europe

While we know that cereals played an important role in the diet of Linearbandkeramik (LBK) and Blicquy/Villeneuve-Saint-Germain (BVSG) populations in the Paris Basin, many questions remain to be answered as to the real contribution of other plants. To assess this topic, the recovery of other lines of data beyond macrobotanicals is crucial: starch grains have the potential to reveal additional information regarding past plant use. However, in Western Europe, in particular, for the Neolithic period, there is a significant lag in the development of the discipline. We, therefore, present how our current reference collection (composed of nearly 100 taxa spread across 35 families) was established, the reasoning behind our plant selections, and where the material comes from. Overall, our work shows that even though not all the selected plant organs produce diagnostic starch grains, it may be possible to broaden the spectrum of plants likely consumed by Early Neolithic (and beyond) populations in the Paris Basin, in particular concerning the use of wild plants and specific plant parts, especially underground storage organs (tubers, rhizomes, roots, bulbs, etc.). We believe our research will help guide future scholars in the creation of their own starch grain reference collection and to carry out such analyses on archaeological material from this region by consulting our image database. We conclude by providing a brief summary of what the starch grain record in the Paris Basin tells us to date on ancient plant use.