Estimating spatial variations in soil organic carbon using satellite hyperspectral data and map algebra

This study evaluated the effectiveness of using Hyperion hyperspectral data in improving existing remote-sensing methodologies for estimating soil organic carbon (SOC) content on farmland. The study area is Big Creek Watershed in Southern Illinois, USA. Several data-mining techniques were tested to calibrate and validate models that could be used for predicting SOC content using Hyperion bands as predictors. A combined model of stepwise regression followed by a five hidden nodes artificial neural network was selected as the best model, with a calibration coefficient of determination (R 2) of 78.9% and a root mean square error (RMSE) of 3.3 tonnes per hectare (t ha−1). The validation RMSE, however, was found to be 11.3 t ha−1. Map algebra was implemented to extrapolate this model and produce a SOC map for the watershed. Hyperspectral data improved marginally the predictability of SOC compared to multispectral data under natural field conditions. They could not capture small annual variations in SOC, but could measure decadal variations with moderate error. Satellite-based hyperspectral data combined with map algebra can measure total SOC pools in various ecosystem or soil types to within a few per cent error

Nutritional and additive uses of chitin and chitosan in the food industry

Chitin is the first polysaccharide identified by man. Chitin and its numerous oligomeric and monomeric, acetylated or deacetylated derivates have many physiological functions and applications. Chitin is found in the cuticles of arthropods and is a major constituent of cell walls from fungal, yeast and algae, from where chitin can be extracted chemically, enzymatically or by fermentation. The principal sources of chitin and chitosan are actually crustacean shells. Worldwide, more than 13.000.000 tons of crustaceans are caught from marine habitats each year, thus generating huge amounts of food waste. The unique biodegradability, biorenewability, biocompatibility, physiological inertness and hydrophilicity of chitin and chitosan make them of high interest for research and industry. In this chapter, we review the use of chitin, chitosan and their oligomers and monomers as food additives. In particular, their use in the regulation of lipid digestion and hypocholesterolemia, their functioning as an antigastritic agent and prebiotic is highlighted. Literature shows that oligomerization and the degree of deacetylation influences the development of chitin/chitosan-based nutraceuticals. The absence of chitinases and chitosanases in the human gut renders those biopolymers resistant to even partial degradation. For food applications, they are used as emulsifying, fining, thickening and stabilizing agents, antioxidants, and low calories food mimetics