Isolation of pectin-enriched products from red beet (Beta vulgaris L. var. conditiva) wastes: composition and functional properties.

The present work was dedicated to the development of an extraction process for red beet (Beta vulgaris L. var. conditiva) by-products that preserves the high molecular weight of the macromolecules with the primary aim of waste upgrading. Our study concerns the extraction of pectin-enriched products with potential thickening properties for their usage in food formulation, as well as with some healthy physiological effect, by using citrate buffer (pH = 5.2) either alone or with enzymes (hemicellulase or cellulase) active on cell wall polysaccharide networks. Considering that red beet tissue contains ferulic acid, which cross-links pectin macromolecules through arabinose residues to anchor them into the cell wall, an alkaline pretreatment was also evaluated in order to perform polysaccharide hydrolysis in the cell wall network to accomplish higher renderings. Chemical composition and yield, as well as the in vitro glucose retention exerted by the isolated fiber products were finally analyzed.

Inhibitory action of potassium sorbate degradation products against Staphylococcus aureus growth in laboratory media.

The inhibitory action of potassium sorbate (KS) degradation products against Staphylococcus aureus growth was examined in model aqueous systems. KS degradation products formation was induced by the storage at 70 degrees C for 7 days or at 37 degrees C for 90 days of aqueous systems containing basically brain heart infusion, yeast extract and different amounts of KS at pH 5.5. After storage, residual amounts of KS were measured and each system was inoculated with a pool of three S. aureus strains at 10(4) colony forming units/ml. Degradation products from KS generally inhibited S. aureus growth by two to three log cycles. However, the population of S. aureus reached a higher level when the degradation products were formed at 37 degrees C suggesting that the nature of the degradation products seemed to depend on the temperature at which they were produced. The inhibitory activity produced by KS degradation products along with residual amounts of KS was smaller than the one produced by the initial amounts of the preservative.

Determination of nitrites in meat systems: An improved procedure.

Various analytical methods for nitrite determination in meat products, based on extraction of the preservative through digestion at 60-80 °C followed by colorimetric analysis gave relatively poor recoveries (44-65%) when applied to raw beef. An improved procedure was developed based on disintegration and dispersion of beef with sand prior to the extraction step and on the use of a higher concentration of N-(1-naphthyl) ethylenediamine dihydrochloride than normally used. The proposed technique resulted in almost 93% recovery of nitrites and showed a high precision revealed in a variation coefficient of 8̃%.

Sorbic acid stability in meat products of reduced water activity.

This study investigated the behavior of sorbic acid in shelf-stable meats with 0.91 water activity during processing (70 °, 80 °, 90 °C) and accelerated storage (33 °, 45 °, 57 °C). In meat systems stored at 70 °, 80 ° and 90 °C, after approximately 0·5-3 days, the destruction rate of sorbic acid diminished. This change in behavior (break) was probably caused by the limited availability of oxygen and/or the inhibitory action of nonenzymatic browning products on sorbate destruction. Before the break, the rate constants were found to be related to temperature, pH, the acid used to adjust it and the humectants added to depress water activity (NaCl, glycerol, the mixture NaCl 3·5% and glycerol). After the break, none of the above mentioned effects were observed. In meat systems stored at 33 °, 45 ° and 57 °C the rate of destruction was constant with time. The rate constants of meat systems were higher than the ones obtained for aqueous systems of similar composition, revealing that meat components played an important role in the destruction of sorbates.

Development of a Shelf-Stable Banana Purée by Combined Factors: Microbial Stability.

A preservation process based on the "hurdle" effect for obtaining a shelf-stable banana purée was developed. The microbial stability of the purée was challenged with inoculation of osmophilic and non-osmophilic yeasts, various molds, Bacillus coagulans , Clostridium pasteurianum and Clostridium butyricum . It was shown that growth of both native and inoculated flora may be prevented for at least 120 days storage in banana purée by adjusting water activity (aw) to 0.97, pH to 3.4, adding 250 ppm of ascorbic acid (AA), 100 ppm of potassium sorbate (KS) and 400 ppm of sodium bisulphite (NaHSO3), and applying a mild heat treatment.