Determination of alginate in dairy products.
Abstract Comprehensive study was made of the precipitability of several hydrocolloids and other related compounds by divalent cations and, specifically, of the optimum conditions for recovering alginate from milk and dairy products by precipitation as calcium, strontium, and manganese salts. In aqueous dispersion, these cations selectively precipitated alginate, pectinic acids, and pectic acid. Alginate was recovered from milk, chocolate milk, ice cream, cheese spreads, cream cheese spreads, and other products by predigesting the mixture with papain, clarifying the digest with Celite 535 and charcoal, filtering and converting any pectin, pectinic acid, and pectic acid to galacturonic acid by pectinmethylesterase (pectinesterase) and polygalacturonase. Then, calcium chloride was added to the filtrate. The calcium alginate precipitate was washed free of sugars, dispersed by sodium hexametaphosphate, and the amount of alginate in the dispersion determined by the phenol-sulfuric acid test. Recoveries obtained were 96-101% for water dispersions, 92-96% for milk, 90-95% for ice cream, and 85-95% for cheese products.
A novel alginate quantification method using high-performance liquid chromatography (HPLC) for pretreatment of Saccharina japonica
A new analysis method for alginate quantification in the brown alga, Saccharina japonica, was developed and evaluated. In this method, (1) alginate was treated with Na2CO3; (2) the alginate-derived compound in the hydrolysate was analyzed using high-performance liquid chromatography (HPLC); and then, (3) one of the HPLC peaks was selected and used to establish the standard calibration curve to estimate the intact alginate content in the raw material. The results obtained using the new method were verified by the Kennedy and Bradshaw method, which confirmed that the new method can be an effective method for the estimation of the alginate content in S. japonica. An experimental equation was developed to estimate the alginic acid concentration in the hydrolysate obtained from Na2CO3 treatment of the model compound (Sigma Na-alginate) at various reaction conditions on the basis of the correlation between estimated alginic acid contents and combined severity factors (CSF). The statistical analysis confirmed that the equation gave consistent results, i.e., approximately 81 % of the test groups lie within <±10 % standard deviation of the mean.
D'une application pratique des indices bio-météorologiques
Abstract The purpose of the author is to determine statistically in what part of Switzerland maize could be cultivated with certain chance of rentability. The author gives first the method he used for determining the biometeorological index of four species of maize which were selected by the Swiss agronomical research stations. He has considered two possibilities for the growing period: ( a ) raising-ripening (l'approche globale); ( b ) raising-flowering, flowering-ripening (l'approche fractionee). From the biometeorological index, he calculated retrospectively the ripening time of these four species in the years 1901–1965. Assuming a priori that maize should be harvested before October 15th at the latest, he calculated, for a number of meteorological stations, the relative number of years when such conditions were fulfilled. Dividing the country in regions of similar mesoclimates and sorting these stations per region, it is possible to average the maximum altitude where maize can ripen at least 7, 8, 9 and 10 times within 10 years. Finally, taking into account the exposure and ground slope, he draws maps of the theoretically possible extension area, which maps are more reliable and detailed than the ones derived from actual means.