No description available.

Static ultra-high pressure (200, 270, and 340 MPa) and sinusoidal and step-pressure (0-270 MPa) pulses were compared by determining their effects on bacteria and yeast survival counts. Samples were commercial pineapple chunks used as is and fresh cut pineapple and pineapple juice inoculated with Saccharomyces cerevisiae 2407-1a. Surviving bacteria and yeast counts were determined using plate count agar (PCA), acidified potato dextrose agar (PDA) and yeast extract dextrose agar (YEPD). Commercially acceptable reduction of microflora for pineapple (greater than 2.5 log cycles) were observed at static pressure of 340 MPa for 15 min at three temperatures (~4, 21, and 38°C). Longer process times (40 and 60 min) at this pressure did not result in further significant count reductions. Lower pressure treatments, 270 and 200 MPa for 15 min, at these temperatures reduced the microbial population of pineapple by 1-2 log and less than one log, respectively. Static pressures treatments of 270 and 340 MPa at 21°C were found to reduce bacterial and yeast counts by 5-log cycles on inoculated fresh cut pineapple. Total bacteria and yeast counts remained <25CFU/plate after a 1/10 sample dilution during 60 days of storage at 4°C. Sinusoidal and step-pressure pulses were compared with static pressure treatments for the inactivation of S. cerevisiae 2407-1 a in pineapple juice. No inactivation was observed after 40-4,000 fast sinusoidal pulses (10 cycles/s) at 4-400 s in the 235-270 MPa range. Static 270 MPa treatments at 40 and 400 s resulted in 0.7 and 5.1 decimal reductions, respectively. Slower 0-270 MPa step pulses at 0.1 (10 pulses), 1 (100 pulses) and 2 (200 pulses) cycles/s with 100 s total on-pressure time resulted in 3.3, 3.5, and 3.3 decimal reductions, respectively. A comparable static pressure treatment resulted in 2.5 decimal reductions. Changing the on-pressure/off-pressure time ratio showed that treatments with longer on-pressure time were more effective. Step pressure pulses (0-270 MPa) on inoculated pineapple chunks for 100s at 0.1 (10 pulses, T3) and 2 (200 pulses, T5) cycles/s were more effective than a 100 s static 270 MPa (T1). After 30 days of refrigerated storage T1 samples showed >10³CFU/g in bacteria and yeast counts, while T3 and T5 had < 10CFU/plate after a 1/10 sample dilution. Both 5 and 10 min step pulsed 0-270 MPa treatments were as effective as 15 min static 270 and 340 MPa. Treatments T3 and T5 for 5 min yielded 0-4 CFU/plate after a 1/10 sample dilution during 30 days of refrigerated storage and recovery of pressure-injured cells was not observed. Static 15 min pressure at 270 MPa and 340 MPa resulted in 0-10 and 0-8 CFU/plate after a 1/10 sample dilution during the same 30 days of refrigerated storage. Step pressure treatment seems to be more effective than static pressure for inactivating bacteria and yeast in pineapple; recovery of pressure-injured cells was not observed under refrigerated storage conditions. / Graduation date: 1997

High pressure (HP) processing, a novel technology, has excellent potential for non-thermal preservation of apple juice, the largest consumed fruit juice in North America. The objective of this research was to evaluate the application of HP treatment for inactivation of enzymes and destruction of microorganisms in apple juice. HP inactivation kinetics of selected enzymes (amylase, pectin methyl esterase and polyphenol oxidase) and microorganisms [Leuconostoc mesenteroides, Pichia membranaefaciens and Zygosaccharomyces badii, Escherichia coli (29055) and Escherichia coli (O157:H7)] in apple juice were evaluated under various test conditions (100--400 MPa, 0--60 min and 6--40°C) using a central composite design of experiments. The enzymes selected were of importance in apple juice preparation and/or storage stability of the processed juice. Microorganisms included those that are responsible for spoilage and/or public health concern as well as those that are indicative of unsanitary handling conditions. / Enzyme inactivation and microbial destruction due to pressure followed a dual-effect model consisting of a pressure pulse effect (PE) and a subsequent semi-logarithmic (first order) inactivation during the pressure hold-time. In general, results showed that inactivation of enzymes and destruction of microorganisms was more prominent at higher-pressure levels, higher temperature and longer treatment times, and at lower pH levels of juice. Pressure pulse effect was dependent on pressure level, with higher PE achieved at higher pressures. During the pressure-hold, as expected, the associated decimal reduction times (D values) decreased with an increase in pressure. Pressure dependency of D values was well described by the conventional death time model. The pressure resistance of enzymes and microorganisms varied, but complete inactivation of enzymes and destruction of microorganisms was possible with the combination of lower pH, higher pressure and higher temperatures. / Commercial PME from a citrus source was more pressure sensitive than PME from microbial source. Spoilage bacteria (L. mesenteroides) were more pressure resistant than the yeasts. E. coli enumerated on an enrichment media (supporting both injured and healthy cells) showed larger survivors and a greater resistance than on a more selective media. An increasing number of cells got injured than killed with the application of pressure treatment until they were all finally injured or killed. High-pressure treatment (pulse at 400 MPa or by holding about 10 min at 350 MPa and 30°C) resulted in complete destruction of the pathogenic microorganism E. coli (O157:H7) ensuring the public health safety of the process.

Thesis (M.A.)--Ohio University, March, 2006. / Title from PDF t.p. Includes bibliographical references (p. 78-86)

Devido ao aumento do consumo de sucos de uva, o controle da qualidade é uma realidade em todos os países produtores e consumidores desse produto. A forma mais comum de adulteração é através da substituição por suco de maçã. As amostras adulteradas podem ser identificadas através de análises específicas, pois o suco de maçã possui alguns compostos que a uva não apresenta ou possui pequenas quantidades, como a florizina e o sorbitol. Portanto, métodos analíticos capazes de identificar a composição de sucos de uva e determinar sua autenticidade são necessários para garantir um controle eficaz da qualidade dos sucos de uva. Por esta razão, o presente trabalho teve como objetivo validar os métodos analíticos da florizina e do sorbitol para detectar adição de suco de maçã em suco de uva. Inicialmente, foram validados os métodos para análise de florizina e sorbitol, realizados em cromatografia líquida. Após a validação dos métodos, foram realizados testes de adições de suco de maçã das cultivares Gala e Fugi em sucos de uva das cultivares Concord, Isabel e Bordô, e, foram analisados sucos de uva e maçã comerciais. Todos os sucos de uva que apresentaram concentração elevada de sorbitol também apresentaram concentração elevada de florizina. Através dos resultados deste estudo, observou-se que os métodos da florizina e do sorbitol são eficazes para detectar a adição de suco de maçã em suco de uva. / Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-06-16T13:53:53Z No. of bitstreams: 1 Dissertacao Fernanda Rodrigues Spinelli.pdf: 1344721 bytes, checksum: 0bc678dfb56889bf18f2bec97cb8c74e (MD5) / Made available in DSpace on 2014-06-16T13:53:53Z (GMT). No. of bitstreams: 1 Dissertacao Fernanda Rodrigues Spinelli.pdf: 1344721 bytes, checksum: 0bc678dfb56889bf18f2bec97cb8c74e (MD5) / Due to the increased consumption of grape juice, quality control is a reality in every country producers and consumers of this product. The most common form of adulteration is by substitution with apple juice. The adulterated samples can be identified by specific analyzes, as apple juice has some compounds that the grape does not have or has in small amounts, as phlorizin and sorbitol. Therefore, analytical methods capable of identifying the composition of grape juices and determine its authenticity are needed to ensure effective control of the quality of the grape juices. For this reason, the present study aimed to validate the analytical methods of phlorizin and sorbitol to detect addition of apple juice in grape juice. Initially, the methods were validated for the analysis of phlorizin and sorbitol, carried out in liquid chromatography. After validation of the methods, tests were conducted additions of apple juice cultivars Gala and Fugi in grape juices from cultivars Concord, Isabel and Bordô, and were analyzed grape and apple commercial juices. All grape juices show that high concentrations of sorbitol also showed high concentration of phlorizin. Through this study, it was observed that the methods of phlorizin and sorbitol are effective to detect the addition of apple juice grape juice.

Devido ao aumento do consumo de sucos de uva, o controle da qualidade é uma realidade em todos os países produtores e consumidores desse produto. A forma mais comum de adulteração é através da substituição por suco de maçã. As amostras adulteradas podem ser identificadas através de análises específicas, pois o suco de maçã possui alguns compostos que a uva não apresenta ou possui pequenas quantidades, como a florizina e o sorbitol. Portanto, métodos analíticos capazes de identificar a composição de sucos de uva e determinar sua autenticidade são necessários para garantir um controle eficaz da qualidade dos sucos de uva. Por esta razão, o presente trabalho teve como objetivo validar os métodos analíticos da florizina e do sorbitol para detectar adição de suco de maçã em suco de uva. Inicialmente, foram validados os métodos para análise de florizina e sorbitol, realizados em cromatografia líquida. Após a validação dos métodos, foram realizados testes de adições de suco de maçã das cultivares Gala e Fugi em sucos de uva das cultivares Concord, Isabel e Bordô, e, foram analisados sucos de uva e maçã comerciais. Todos os sucos de uva que apresentaram concentração elevada de sorbitol também apresentaram concentração elevada de florizina. Através dos resultados deste estudo, observou-se que os métodos da florizina e do sorbitol são eficazes para detectar a adição de suco de maçã em suco de uva. / Due to the increased consumption of grape juice, quality control is a reality in every country producers and consumers of this product. The most common form of adulteration is by substitution with apple juice. The adulterated samples can be identified by specific analyzes, as apple juice has some compounds that the grape does not have or has in small amounts, as phlorizin and sorbitol. Therefore, analytical methods capable of identifying the composition of grape juices and determine its authenticity are needed to ensure effective control of the quality of the grape juices. For this reason, the present study aimed to validate the analytical methods of phlorizin and sorbitol to detect addition of apple juice in grape juice. Initially, the methods were validated for the analysis of phlorizin and sorbitol, carried out in liquid chromatography. After validation of the methods, tests were conducted additions of apple juice cultivars Gala and Fugi in grape juices from cultivars Concord, Isabel and Bordô, and were analyzed grape and apple commercial juices. All grape juices show that high concentrations of sorbitol also showed high concentration of phlorizin. Through this study, it was observed that the methods of phlorizin and sorbitol are effective to detect the addition of apple juice grape juice.

Despite earlier indirect evidence that an antral chalone exists, no such inhibitor has been found in antral extract. Recently, interest in the question of an antral inhibitory mechanism has been revived by studies that showed that for a given rise in serum gastrin caused by antral distension, the response of both the innervated and denervated stomach is greatly enhanced by vagal denervation of the antrum. While this study suggested a neuro-humoral character of the antral inhibitory mechanism, it gave no indication as to the source of the inhibitor. Subsequent studies, however, suggested that neither the antrum nor the CNS was the source for this inhibitor. The initial aim of this study was to investigate the fundus as a possible source of the inhibitor by studying the effect of proximal gastric vagotomy on the antral inhibitory mechanism initiated by distension. The results gave clear indication that the inhibitor was indeed released from the fundus; indeed, the antral inhibitory mechanism was in reality a fundic one. Once the fundus was shown to be the source of the inhibitor, it was necessary to establish whether this inhibitor did in fact reside in the fundic mucosa. Four dogs were prepared with a denervated fundic pouch (or Heidenhain pouch, HP), and a fistula of the main, innervated stomach (gastric fistula, GF). The acid secretory responses of both the HP and GF to graded doses of pentagastrin and histamine was studied. In addition both the secretion of acid and the response of immunoreactive gastrin in the blood in response to a standard meal of 15% liver extract was studied. All these experiments were repeated after excision of the fundic mucosa of the main stomach. The results show that excision of the fundic mucosa reduced the GF acid secretion to the stimuli by 85-100%. By contrast, the maximal HP acid secretion increased by 247% in response to pentagastrin and 200% in response to histamine. The increase in the response to submaximal doses of these exogenous stimuli was even greater. Similarly, the peak 30 minutes HP output in response to feeding increased by 418%. Fundic mucosal excision also resulted in the increase in both basal (from 36±3 to 248±37 pg/ml) and food-stimulated response (from 168±12 preoperatively to 392±49 pg/ml postoperatively). Since the intragastric pH was held constant at 5.5 during the meal tests both before and after the operation, the augmented gastrin response could not be attributed to reduced acid secretion caused by excision of the fundic mucosa. From these studies it can be concluded that: (1) antral distension releases an inhibitor from the fundus; (2) excision of the fundic mucosa results in increased response of the HP to both submaximal and maximal doses of pentagastrin and histamine indicating that both the sensitivity of the oxyntic cell and parietal cell mass has increased; (3) excision of the fundic mucosa results in increased basal and food-stimulated gastrin response independent of the pH of the meal suggesting removal of an inhibitor of gastrin release. / Surgery, Department of / Medicine, Faculty of / Graduate

No description available.

No description available.

Improved sensitive techniques were developed for the determination of soluble proteins in grape, juice and wine. These techniques which permitted direct sample analysis without prior dialysis or concentration, were used for: 1) characterization of heat unstable proteins, 2) evaluating the effect of bentonite fining and ultrafiltration (UF) on the soluble proteins and heat unstable proteins in Gewurztraminer and Riesling juices and wines. Protein molecular weights (MW), isoelectric points (pI) and glycoproteins were determined by using LDS-polyacrylamide gel electrophoresis and 2-dimensional isoelectric focusing (IF)-LDS electrophoretic techniques with silver staining as well as protein blotting for glycoprotein detection. Relative concentrations of proteins in stained gels were determined by laser scanning densitometry. Bentonite fining tends to remove higher pi (5.8-8.0), intermediate MW (32,000-45,000) protein fractions first. In general, it is necessary to remove the lower pI (4.1-5.8), lower MW (12,600 and 20,000-30,000) fractions and glycoproteins to "protein stabilize" wines to heat testing. Unstable proteins precipitated by heat test were recovered and analyzed. These proteins were mainly of low MW (<30,000) and primarily glycoproteins. Protein fractions with MW of greater than 14,000 were more heat sensitive than lower MW fractions. Wines and juice were ultrafiltered with Romicon and Millipore systems operated with membranes of "nominal MW cut-off (MWCO)" of 10,000-100,000 daltons. A progressive increase in membrane retention of soluble protein was observed with decreasing MWCO, up to 99% of wine protein being retained with membranes of 10,000 dalton MWCO. However, certain high MW protein fractions also remained in permeates even with 10,000 MWCO membranes. In the order of 3-2 0 mg protein/L frequently remained in UF wine permeates, this correlated with the periodic detection of heat instability and of a low bentonite requirement for "protein stability" as determined by sensitive heat testing. "Protein stability" could be obtained with MWCO of 10,000 and 3 0,000; however, when not obtained, reductions in the order of 80-95% in "bentonite demand" were achieved. Protein stabilization of wines by UF is similar to that by bentonite fining in that it is necessary to remove the lower MW (12,600 and 20,000-30,000), lower pI (4.1-5.8) fractions, and glycoproteins to stabilize wines to heat testing. UF membranes were more effective at retaining wine proteins than juice proteins. UF juices were more susceptible to heat induced haze formation than UF wines. / Graduation date: 1986