ABSTRACT
D-glucono-1,5-lactone differs from D-glucopyranose only in that it has a C = O group instead of CHOH group at carbon atom number one. The molecule therefore possesses an intact 3,4 alpha-glycol group and is sweet. However, it autohydrolyses in water solution at room temperature, forming D-gluconic acid and D-glucono-1,4-lactone. As the solution pH falls it becomes sweet-sour and eventually almost completely sour as the generated hydronium ions dominate both the solution properties and the taste perceptions elicited. It is shown that the ratio of generated hydronium ions to unchanged lactone accords with anticipated taste quality during the first 28 min of autohydrolysis. Changes in both apparent specific volume and apparent isentropic compressibility illustrate increasing solute-solvent interaction and increasing disturbance of water structure during the course of autohydrolysis. These changes are consistent with the concurrent sweet to sour change, but do not explain the weak bitterness which also accompanies them.
Subject(s)
Gluconates/chemistry , Lactones/chemistry , Taste/physiology , Adult , Age Factors , Female , Glucose/chemistry , Humans , Hydrogen-Ion Concentration , Hydrolysis , Male , Middle Aged , Tongue/physiologyABSTRACT
The effect of the sweetness inhibitor 2(-4-methoxyphenoxy)propanoic acid (sodium salt) (Na-PMP) on the taste and temporal properties of a range of bitter-sweet stimuli was determined using a trained sensory panel. Na-PMP was found to be an effective inhibitor of the sweetness response of all stimuli tested, reducing both sweetness intensity and persistence. The inhibitor was found to be specific to sweet taste, no reduction in bitterness intensity or persistence was observed at the concentrations of Na-PMP employed in this study. The results therefore do not support the claim of Fuller and Kurtz (1991), that Na-PMP is a potent bitterness inhibitor, but rather support the existence of two distinct receptor sites/loci in sweet and bitter chemoreception.
Subject(s)
Propionates/pharmacology , Sweetening Agents/pharmacology , Taste/drug effects , Adult , Female , Humans , Male , Middle Aged , Phenyl EthersABSTRACT
Mucin-positive epithelial mesothelioma is a rare, frequently unrecognized entity that should not be misinterpreted as metastatic adenocarcinoma, as each is associated with differing treatment and prognosis. Presented herein is a case of an acidic and neutral mucin-positive papillary mesothelioma of the right pleura, with cytologic, histologic, histochemical, immunohistochemical, and ultrastructural evaluation.
Subject(s)
Mesothelioma/chemistry , Mesothelioma/pathology , Mucins/analysis , Pleural Neoplasms/chemistry , Pleural Neoplasms/pathology , Adenocarcinoma/diagnosis , Adenocarcinoma/pathology , Adenocarcinoma/ultrastructure , Diagnosis, Differential , Humans , Immunohistochemistry , Male , Mesothelioma/diagnosis , Microscopy, Electron , Middle Aged , Pleura/pathology , Pleura/ultrastructure , Pleural Neoplasms/ultrastructure , PrognosisABSTRACT
The levels of nitrite used in curing pork are in excess of those required to produce an adequate cured colour, but the minimum level for pink coloration to be visible has not been established experimentally. This paper demonstrates the effect of low nitrite levels from local surface application to pork muscle, simulating inadvertent contamination from work surfaces. An homogenate is used for comparison in which the nitrite was evenly distributed throughout the product. The results indicate that surface contact with nitrite produces essentially the same pattern of colour change as in the homogenate. Visible pink coloration was evident from 1-2 mg kg(-1) sodium nitrite absorbed.
ABSTRACT
Two hot deboning procedures for producing vacuum packed primal beef joints were compared with conventional side chilling followed by cold deboning. Cold shortening toughness was avoided in the hot procedures either by a delay before chilling or by electrical stimulation of the carcass. Overall evaporative losses were 0·6% with hot deboning and 1·9% with cold deboning. Hot deboning reduced drip loss but the effect was smaller after electrical stimulation. The colour of large muscles which cool unevenly on the side was more uniform after hot deboning, but again the improvement was smaller after electrical stimulation. There was no difference in bacterial contamination or growth on hot and cold deboned meat, and instrumental and sensory assessments confirmed that eating quality was similar for all three treatments.
