Search

Abstract: Near infrared spectroscopy has been extensively used to determine the water behaviour at different temperatures and different physical state. The purpose of the present work was to investigate the spectroscopic response in the range 1100–2400 nm of solutions of glucose, fructose, and sucrose at concentrations 5–65%. Data indicate that by increasing sugar concentration the water band becomes more symmetric and there is a shift of the absorption maximum toward longer wavelengths. Spectra were interpreted in terms of “structure-maker” and “structure-breaker” effects of increasing sugar concentration. Sugars at low concentrations behave as structure breaker of the water cluster, while at higher concentrations they act as structure makers. These results could be of some interest when monitoring by NIR processes as freezing, freeze-drying, drying, cryoconcentration, etc. of fruits and vegetables, where the removal or separation of large amounts of water induce the formation of very concentrated sugars solutions. [Copyright &y& Elsevier] more...

FT-IR spectroscopy was used to analyse 112 samples of "Provola" cheese, coated with biodegradable wax or paraffin, at 90 and 120 days of shelf-life, in order to verify the discriminating power of this spectroscopic technique. The influence of the two different kinds of wax was also studied. Spectral data were processed using Mean Centre algorithm and transformed into second derivative using the Savitzky-Golay algorithm. Principal Component Analysis was applied to optimise the information given by the spectral data sets. FT-IR spectroscopy was able to classify samples on the basis of shelf-life and to detect the differences in the lipolytic trend due to the nature of the wax used. [ABSTRACT FROM AUTHOR] more...

Thirty-eight Italian Friesian first-lactation cows were allocated to 2 groups to evaluate the effect of 1) an automatic milking system (AMS) vs. milking in a milking parlor (MP) on milk fat characteristics; and 2) milking interval (≤480, 481 to 600, 601 to 720, and >720 min) on the same variables. Milk fat was analyzed for content (% vol/vol), natural creaming (% of fat), and free fatty acids (FFA, mEq/100 g of fat). Distribution of milk fat globule size was evaluated to calculate average fat globule diameter (d1), volume-surface average diameter (d32), specific globule surface area, and mean interglobular distance. Milk yield was recorded to calculate hourly milk and milk fat yield. Milking system had no effect on milk yield, milk fat content, and hourly milk fat yield. Milk from AMS had less natural creaming and more FFA content than milk from MP. Fat globule size, globular surface area, and interglobular distance were not affected by milking system per se. Afternoon MP milkings had more fat content and hourly milk fat yield than AMS milkings when milking interval was >480 min. Milk fat FFA content was greater in AMS milkings when milking interval was ≤480 min than in milkings from MP and from AMS when milking interval was >600 min. Milking interval did not affect fat globule size, expressed as d32. Results from this experiment indicate a limited effect of AMS per se on milk fat quality; a more important factor seems to be the increase in milking frequency, generally associated with AMS. [ABSTRACT FROM AUTHOR] more...

Abstract: Crescenza is a fresh cheese in which “freshness” is associated with low acidity, limited proteolysis, and no bitter taste. In this study, FT-NIR and FT-IR spectroscopy was applied to evaluate the shelf-life period in which “freshness” is maintained. Cheese samples were analysed at different times for 20 days. Spectral data were collected using a FT-NIR spectrometer with an optic fibre (from 12000 to 4000cm−1), and a FT-IR spectrometer with an ATR cell (from 4000 to 700cm−1). Principal component analysis was able to detect the decrease of Crescenza “freshness” and to define the critical day during shelf-life. These results are in agreement both with those reported in previous studies and with those of physico-chemical and chemical tests. The principal absorption bands relating to the milk components involved were determined. The advantage of using IR spectroscopy is to rapidly draw a profile of the product related to its total quality. [Copyright &y& Elsevier] more...