Pectins differing in their degree and pattern of methylesterification are important in diverse aspects of plant physiology and also in many industrial applications. Determination of methylesterification fine structure and knowledge of enzyme specificities in modification and fragmentation of pectin are key to understanding the relationship between structure and function. The development of methodologies for the detection, separation and sequencing of different partially methylesterified oligogalacturonides (Me-OGAs) is consequently very important. Polysaccharide analysis using carbohydrate gel electrophoresis (PACE) has been shown to be powerful for the quantitative resolution of species different in degree of polymerization (DP) and/or degree of methylesterification (DM). Mass spectrometry (MS) has, to date, been the only tool with which to obtain isomeric information. However, it is not quantitative, and the presence of isobaric species makes the interpretation of the fragmentation patterns complicated. Here, we present evidence that Me-OGAs with the same DP and DM but different patterns of methylesterification (structural isomers) can easily be separated and quantified using PACE.
Pectins are traditionally divided into two groups, high methoxy and low methoxy. The groupings determine the charge of the pectin and the gelation mechanism. However, not as yet extensively studied is the impact on gelation of the distribution of the charges as characterized by an absolute degree of blockiness (DBabs). The aim of this study was to characterize rheologically the acid gelation of a pectin with a high DBabs and a degree of methyl esterification of ∼ 37%, in the absence and presence of monovalent ions. The results obtained suggest that a pectin with a blocky charge distribution at pH conditions close to or below the pKa exhibits weak gel-like properties at intermediate frequencies, despite the absence of a permanent network structure. The addition of monovalent ions changed the rheological behavior to resemble that of a strong gel whose properties depended on the type and concentration of the ions.
Textiles are a promising base material for flexible and wearable electronic applications such as sensors, actuators, and energy harvesters. An essential component in such electronic textiles (e‐textiles) is electrically conducting yarns. Here, a continuous dyeing process is presented to convert an off‐the‐shelf silk sewing thread into a wash and wear resistant functional thread with a conductivity of about 70 S cm−1; a record high value for coated yarns. An aqueous ink based on the conducting polymer:polyelectrolyte complex poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is modified, to produce more than 100 m of dyed conducting threads, which are subsequently converted into e‐textiles by both hand weaving and machine embroidery. The yarns are resistant to abrasion and wear, and can be machine washed at least 15 times with retained electronic properties. The woven fabric is used to design a capacitive touch sensor which functions as an e‐textile keyboard.