THE STUDY OF SAMPLING ERRORS IN FACTOR ANALYSIS BY MEANS OF ARTIFICIAL EXPERIMENTS.

2 POINTS OF VIEW ABOUT FACTOR ANALYSIS ARE OFFERED: (1) THE STATISTICAL, IN WHICH SAMPLING FLUCTUATIONS ARE THE RESULT OF THE SAMPLING OF PERSONS, AND (2) THE PSYCHOMETRIC, IN WHICH INDETERMINACIES RESULTING FROM FLUCTUATIONS IN WHAT IS MEASURED ARE EMPHASIZED. SEVERAL STUDIES SUGGEST THAT THE STANDARD ERROR OF A FACTOR LOADING DUE TO THE SAMPLING OF PERSONS IS ABOUT N-$M$UQ. THIS IS APPROXIMATELY TRUE FOR ANALYTICALLY ROTATED FACTORS. IT IS MORE NEARLY TRUE FOR LEAST-SQUARES ROTATIONS TO THE POPULATION, BUT THIS GENERALIZATION IS LIMITED BY THE LACK OF CONTROL OF THE ANGLES OF SEPARATION AMONG THE ROTATED FACTORS IN THE SAMPLE. EVIDENCE IS GIVEN CONCERNING THE INFLUENCE OF TYPE OF FACTORING, SIZE OF LOADING, AND METHOD OF FACTORING. THE DETERMINATION OF THE NUMBER OF FACTORS IS DISCUSSED. EVIDENCE FROM STUDIES OF PSYCHOMETRIC ERROR IS ALSO PRESENTED. (39 REF.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of seed polyphenols in berries from Vitis vinifera L. cv. Shiraz

Polyphenols extracted from the seeds of Vitis vinifera L. cv. Shiraz berries were monitored during berry development. Initially seeds were green, plump and had pliable seed coats, but beginning at veraison the seeds browned in colour, became desiccated and the seed coats hardened. Isolated polyphenols consisted of flavan-3-of monomers ((+)-catechin, (-)-epicatechin and (-)-epicatechin-3-O-gallate) and procyanidins. The procyanidins were maximal in the 3 weeks prior to veraison, increasing little during this period. The amounts of flavan-3-ol monomers increased 5-fold during this same period of time, indicating that the procyanidins and the flavan-3-ol monomers accumulate at different stages. Beginning at veraison, amounts of all polyphenols declined and changed in composition. The decrease in amount followed second-order kinetics. Polyphenol changes after veraison could be explained by oxidation and therefore, electron paramagnetic resonance (EPR) spectroscopy was used to follow the potential development of radical species in the developing seeds. Spectra consistent with a phenoxyl radical were observed in the developing seeds. The concentration of radicals remained low until veraison but then increased, reaching a maximum three weeks later, declining slowly thereafter. Changes in radical intensity together with other documented changes in the seed are consistent with an oxidative event occurring during fruit ripening.     

Resistance of Clostridium perfringens to Varying Degrees of Acidity during Growth and Sporulation

SUMMARY: Viable cells of each of 6 strains of Clostridium perfringens were exposed to 4 levels of acidity during phases of the growth cycle. The selected strains included 4 which had been recovered in association with food poisoning outbreaks and 2 strains not so associated. The growth media tested included Fluid Thioglycollate Medium, DS-sporulation medium and the CP-2V medium proposed by Hauschild.
The level of acidity, length of exposure of the cells, the growth medium employed and the phase in the growth curve influenced the survival of C. perfringens. Exposure of cells grown in DS-sporulation medium to buffers pH 6.0 had little effect on the survival over the 8-hr test period, with somewhat greater sensitivity of cells being demonstrated at pH 4.5. Exposure of cells, similarly produced, to buffer pH 1.0 or 2.0 was much more effective in reducing the percentage of survival, particularly during early log phase and at the onset of sporulation. Based on the 3 growth media utilized, calculated survival curves resulting from exposure of cells to pH 1.0 or 2.0 were erratic in shape, and percentage survival was almost universally less than 10%.
Source of the strain, whether food poisoning or non-food poisoning associated, appeared to have no significant effect on the acid resistance of the cells. The comparatively regular increase in the percentage of survivors after the initiation of sporulation suggests that spores exhibit a greater resistance to acid stress than vegetative cells.
Incubation at temperatures of 37° or O°C, during the time of treatment with the test buffers pH 1.0 or 2.0, produced no consistent change in the percentage of survivors when the cells were grown in FTG.     

COMPARISON OF HEADSPACE SOLID PHASE MICROEXTRACTION AND XAD-2 METHODS TO EXTRACT VOLATILE COMPOUNDS PRODUCED BY SACCHAROMYCES DURING WINE FERMENTATIONS

A modified headspace solid phase microextraction (HS‐SPME) method was compared with Amberlite® XAD‐2 resin for the extraction of volatile compounds. In the HS‐SPME method, volatiles were extracted using an 85 μm polyacrylate fiber from wines that contained a standardized amount of ethanol (10% v/v), NaCl (0.325 g/mL) and internal standards (dodecanol and nonanoic acid). Both extraction procedures yielded high relative recoveries (>92%) and reproducibilities (coefficient of variations ≤ 11%) for the different higher alcohols, esters and medium‐chain fatty acids. Overall, limits of detection for the HS‐SPME and XAD‐2 methods were below sensory threshold concentrations. HS‐SPME and XAD‐2 performed similarly in the analysis of a Riesling wine; however, the HS‐SPME method did not require organic solvents and was generally quicker to perform. In applying the HS‐SPME method, differences in concentrations of volatile compounds produced in Riesling and Chenin blanc wines by 11 different yeast strains were noted.     

NITROSAMINES AND THE INHIBITION OF Clostridia IN MEDIUM HEATED WITH SODIUM NITRITE

During sterilization of a culture medium in the presence of NaNO₂ an inhibitor for the growth of Clostridium was observed. The possibility this might be certain volatile N-nitroso compounds was investigated using CC-MS. The minimum inhibitory concentration (MIC) of NO₂^- in the medium autoclaved with NO; was 40 ppm; in medium to which NO; was added aseptically, the MIC was 640 ppm. Chromatograms showed peaks with retention times similar to N-nitroso compounds; however, structure confirmation with MS showed none contained a nitrosoamine and additional experiments confirmed nitrosamines had no inhibitory effects to growth of Clostridiu.     

Identification and Quantification of the "Popcorn"-like Aroma in Louisiana Aromatic Delia Rice (Oryza sativa, L.)

The “popcorn” like aroma was identified as 2-acetyl-l-pyrroline. Cooked Delia white rice contained almost 300 ng 2-acetyl-1-pyrroline per g (dry weight) rice, while cooked Lemont white rice (nonaromatic cultivar) contained 4 ng per g (dry weight). Delia white rice contained almost four times more 2-acetyl-l-pyrroline as the average (73 ppb) in two batches of Jasmine white rice imported from Thailand and comparably analyzed.     

Palatability and Storage Characteristics of Precooked Beef Roasts

The palatability and storage characteristics of fresh, frozen and precooked beef chuck roasts prepared using added phosphate-salt and vacuum cooking bags were evaluated. Palatability attributes (tenderness, juiciness, beef flavor intensity, and off-flavor intensity) of precooked roasts prepared in vacuum cooking bags with phosphate-salt were as good or better than freshly cooked roasts. Precooked roasts in vacuum cooking bags had the lowest total bacterial counts after storage for 14 and 28 days. A palatable precooked roast beef product was developed that can be stored for 28 days at 4°C.     

Development of Botulinal Toxin and Sensory Deterioration During Storage of Vacuum and Modified Atmosphere Packaged Fish Fillets

Toxin production by C. botulinum type E was studied in cod, whiting, and flounder filets packaged in air-permeable film, vacuum packages and packages flushed with N₂ or CO₂ during storage at 8°, 12° or 26°C. Cod and whiting filets were flushed with CO₂ and stored continuously at 4°C or cycled between 4° or 8° and 26°C. Cod and whiting fillets were flushed with gas mixtures and stored at 8°C or 26°C. Flounder deteriorated rapidly and was rejected by sensory evaluation prior to toxin detection during vacuum or modified atmosphere storage at 12°C and 8°C but after toxin detection at 26°C. Toxin was present either prior to or simultaneously with sensory rejection of cod and whiting fillets for all vacuum or modified atmosphere treatments and temperature regimens.