Umberto Bracco

Production and use of natural antioxidants

We have developed a new industrial process for obtaining natural antioxidants from spices and other vegetables by primarily adapting mechanical and physical treatments. Rosemary, sage, paprika, nutmeg and cocoa shells have been submitted to a mechanical treatment (micronization), and the finely powdered material was extracted with an edible vegetable oil, i.e., groundnut. The antioxidant dissolved in the lipid phase was collected by two-stage falling film molecular distillation to separate the lipid phase to be recycled) from the active, low molecular weight fraction. Antioxidant activity was measured for fats, oils and fat-containing foods by oxygen absorption, head-space analysis (i.e., pentane) extent of secondary degradation products and organoleptic evaluations. Results obtained indicate that molecular distillates from spices, i.e., rosemary derivatives, effectively protect foods against oxidative rancidity.

Frying performance of palm oil liquid fractions

Palm oil liquid fractions were used as frying media in household and industrial fryers and were compared to standard edible oils and fats, such as soybean, groundnut, sunflower, rapeseed and tallow. The analytical evaluation covered free fatty acids, viscosity, smoke and flame points, oxidized fatty acids, nonelution material (NEM), UV differential spectra, polymers and foam index. These values measure the extent of the oil degradation, i.e., oxidation, hydrolysis, splitting and polymerization. Moreover, they were combined with other analytical procedures (fatty acid composition, keeping qualities such as the time necessary for an oxygen-absorbing sample to reach a -0.5 psi pressure in a closed system) in order to have a large analytical control during the frying processes. The data collected show the suitability of edible oils and fats for frying purposes and indicate that palm oil liquid fractions perform satisfactorily as frying media. They have low degradation and produce fried foods with acceptable keeping qualities.

The lipid globules of saccharomyces cerevisiae: A combined chemical and ultrastructural study using ultrathin frozen sections

In unstained ultrathin frozen sections of Saccharomyces cerevisiae all lipid globules show an extremely high contrast due to a strong affinity towards OsO 4 . Uranyl-acetate/lead citrate poststaining of the sections considerably decreases the contrast of the lipid droplets. Two different modes of decolourization are observed: Part of the lipid globules are decolourized at their periphery only whereas others are decolourized homogeneously over their entire cross section. The presence of two different populations of lipid globules is therefore postulated. This is supported by freeze-etching results where two kinds of morphologically different lipid droplets are observed. Chemical analyses on the total lipid fraction revealed data commonly obtained for yeast cells. Even numbered monounsaturated fatty acids account for 70% of the total lipid fraction. Several possible explanations for the peculiar behaviour of the lipid globules during poststaining are forwarded.

Analytical techniques in food emulsifiers

After reviewing some problems arising in the analysis of food emulsifiers, we describe an analytical technique to detect most of them. The analytical method is based on the following procedure: (a) extraction of total lipids from food with a mixture of chloroform-methanol; (b) removal of nonpolar lipids from the lipidic extract by column chromatography with an elution media based on petroleum ether-ethyl ether mixtures; (c) thin layer chromatographic identification of the polar lipids extracted from foods. The validity of the method has been practically checked on some emulsifier-based foods, i.e., chocolates, toppings, ice creams, and whippable creams.