Hydrophobic interaction of 8-anilino-1-naphthalene sulfonic acid (ANS) with proteins is one of the widely used methods for characterizing/detecting partially folded states of proteins. We have carried out a systematic investigation on the effect of ANS, a charged hydrophobic fluorescent dye, on structural properties of acid-unfolded horse heart cytochrome c at pH 2.0 by a combination of optical methods and electrospray ionization mass spectroscopy (ESI MS). ANS was found to induce, a secondary structure similar to native protein and quenching of fluorescence of tryptophan residue, in the acid-unfolded protein. However, the tertiary structure was found to be disrupted thus indicating that ANS stabilizes a molten globule state in acid-unfolded protein. To understand the mechanism of ANS-induced folding of acid-unfolded cytochrome c, comparative ESI MS, soret absorption, and tryptophan fluorescence studies using nile red, a neutral hydrophobic dye, and ANS were carried out. These studies suggested that, at low pH, electrostatic interactions between negatively charged ANS molecules and positively charged amino acid residues present in acid-unfolded cytochrome c are probably responsible for ANS-induced folding of acid-unfolded protein to partially folded compact state or molten globule state. This is the first experimental demonstration of ANS induced folding of unfolded protein and puts to question the usefulness of ANS for characterization/determination of partially folded intermediates of proteins observed under low pH conditions.

Studies were to determine the effect of various factors upon B-vitamin content of cultured yogurt and to compare the B-vitamin contents of cultured and direct acidified yogurt. Incubation of yogurt culture at 42 C for 3 h yielded maximum vitamin synthesis concurrent with optimal flavor and texture qualities. A method was standardized for the manufacture of direct acidified yogurt involving the use of Stabilac acidulant and nonfat dry milk, Carboxymethyl cellulose, gelatin, and Starite. Acidified yogurt showed a slightly higher content of certain B-vitamins than the cultured yogurt due to the contribution made by various food additives. Both cultured and acidified yogurt showed good keeping quality and freedom from microbial contaminants during storage at 5 C for 16 days. However, folic acid and vitamin B12 contents decreased 29 and 60% in cultured yogurt and 48 and 54% in acidified yogurt.

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Usable life of cleaning solutions in a model heat processing unit was studied by evaluation of the nature and quantity of residue remaining on the surface of the equipment after cleaning. Lipoidal residue was recovered from equipment surfaces by ether rinsing. A surface displacement technique was used to quantify the lipoidal material, which was characterized by gas-liquid chromatographic analyses of triglycerides and fatty acid methyl esters. Effects of factors, such as water hardness, rinse water temperature, cleaning solution additives and acid versus alkaline cleaners also were investigated in relation to overall cleaning efficiency. After evaluating limits of reuse of cleaning solutions, used solutions were regenerated by sorption of lipoidal residue on Celite, resulting in restored cleaning effectiveness. When spent-cleaning solutions were circulated in previously cleaned equipment, there was redeposition of lipoidal material onto the equipment surfaces.

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Submission of an original paper with copyright agreement and authorship responsibility.I (corresponding author) certify that I have participated sufficiently in the conception and design of this work and the analysis of the data (wherever applicable), as well as the writing of the manuscript, to take public responsibility for it. I believe the manuscript represents valid work. I have reviewed the final version of the manuscript and approve it for publication. Neither has the manuscript nor one with substantially similar content under my authorship been published nor is being considered for publication elsewhere, except as described in an attachment. Furthermore I attest that I shall produce the data upon which the manuscript is based for examination by the editors or their assignees, if requested.Thanking you.