The total acidity of orange juice is ordinarily determined by titrating a known volume of juice with a standard solution of NaOH, with phenolphthalein as indicator, the result beinog expressed as citric acid. This value includes all the substanees of an acidic nature in the juice that react with NaOH. It so happens, however, that in most fruits the chief substances reacting with NaOH are the or...

Organic acids play pivotal role in flavor and consumer acceptance of fruit beverages. Concentration of some organic acids in citrus juices was determined through HPLC and their retention during refrigerated storage was also evaluated. The concentration of organic acids were in the following pattern Citric Acid> Malic Acid> Ascorbic Acid> Tartaric Acid. Citric acid, malic acid, ascorbic acid and...

Extracts of a fluorescent species of Pseudomonas grown with m-cresol, degrade gentisic acid without isomerization of the ring-fission compound, maleylpyruvate, to give eventually d-malate and pyruvate. d-Malate is also a growth substrate. l-Malate but not d-malate is oxidized by a particulate enzyme not requiring nicotinamide adenine dinucleotide (NAD) or nicotinamide adenine dinucleotide phosp...

Reaction 1 requires DPN and manganous ions. It is specific for Imalic acid; d-malic acid is inactive. TPN cannot replace DPN. Reaction 2 requires the presence of manganous ions. The evidence presented below supports the view that Reaction 1 is a DPN-linked dismutation between Z-malate and pyruvate, resulting from the interaction of lactic dehydrogenase with a DPN-specific “malic” enzyme as show...

This work studies the physiology of Schizosaccharomyces pombe strain 938 in the production of white wine with high malic acid levels as the sole fermentative yeast, as well as in mixed and sequential fermentations with Saccharomyces cerevisiae Cru Blanc. The induction of controlled maloalcoholic fermentation through the use of Schizosaccharomyces spp. is now being viewed with much interest. The...

The roots of barley plants (Hordeum vulgare L. cv Steptoe) were monitored before and after excision for net uptake of carbon dioxide, oxygen, ammonium, potassium, nitrate, and chloride and for their content of sucrose, glucose, fructose, and malic acid. All fluxes began to attenuate within 2 hours after excision. Net potassium uptake returned to control levels 6 hours after excision, but carbon...

The behaviours of the principal NADPH-producing enzymes (glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, cytoplasmic and mitochondrial 'malic' enzyme and NAPD+-dependent isocitrate dehydrogenase) were studied during the development of rat heart and compared with those in brain and liver. 1. The enzymes belonging to the pentose phosphate pathway exhibit lower activities in h...

Morita, Richard Y. (University of Nebraska, Lincoln) and Roger D. Haight. Malic dehydrogenase activity at 101 C under hydrostatic pressure. J. Bacteriol. 83:1341-1346. 1962.-No malic dehydrogenase activity was found to occur at 101 C at various hydrostatic pressures from 1 to 700 atm. However, activity was demonstrated with hydrostatic pressures above 700 atm, with optimal activity at 1,300 atm...

The secondary structure of human brain cytosolic and mitochondrial 'malic' enzymes purified to homogeneity has been investigated by Fourier-transform IR spectroscopy. The absorbance IR spectra of these two isoenzymes were slightly different, but calculated secondary-structure compositions were essentially similar (38% alpha-helix, 38-39% beta-sheet, 14% beta-turn and 9-10% random structure). Th...

Preliminary experiments have shown (1, 2) that, when excised tobacco leaves are cultured in the dark in 0.2 M solutions of potassium succinate or L-malate, a marked stimulation of the formation of citric acid occurs. Furthermore, leaves cultured in succinate increased in their content of malic acid, although culture in L-malate, in the single experiment that has been carried out (2), did not le...