Low pH Inactivation of Polyphenoloxidase in Apple Juice

1990 ◽  
Vol 55 (2) ◽  
pp. 562-563 ◽  
Author(s):  
G. P. ZEMEL ◽  
C.A. SIMS ◽  
M. R. MARSHALL ◽  
M. BALABAN
Keyword(s):  
Apple Juice ◽  
Low Ph ◽  
Ph Inactivation

Evaluation of foodborne pathogen die-off in back-sweetened wine and apple cider models

2021 ◽  
Author(s):  
Zirui Ray Xiong ◽  
Anqi Chen ◽  
Glycine Zhujun Jiang ◽  
Alisha G Lewis ◽  
Christine D Sislak ◽  
...  
Keyword(s):  
Foodborne Pathogens ◽  
Apple Juice ◽  
Foodborne Pathogen ◽  
Grape Juice ◽  
White Wine ◽  
Low Ph ◽  
Alcoholic Beverages ◽  
Pathogen Inactivation ◽  
Apple Cider ◽  
Log Reduction

Wine and alcoholic apple cider are commonly back-sweetened with unpasteurized juice to produce fresh, natural, and palatable sweetened alcoholic beverages. Foodborne pathogens may be introduced from unpasteurized juice into alcoholic beverages through this back-sweetening process. Although pathogens generally do not survive under low pH conditions or high alcohol environment, the die-off of these pathogens has not been established to ensure the safety of the products. To determine the safety of these back-sweetened beverages, we evaluated the survival of three common foodborne pathogens, E. coli O157:H7, Salmonella enterica , and Listeria monocytogenes in modified white grape juice and apple juice models. White grape juice and apple juice were modified with hydrochloric acid/sodium hydroxide and ethanol to achieve conditions that are similar to the back-sweetened white wine and alcoholic apple cider. Pathogen cocktails were inoculated separately into modified juice models and their survival in the juice models were recorded over a 96-hour period. Our results show that a combination of low pH and high ethanol content resulted in a faster pathogen die-off compared to higher pH and lower ethanol conditions. The holding times required for different combinations of pH and ethanol concentration for each juice model to achieve 5-log reduction were reported. This research provides data to validate pathogen die-off to comply with Juice HACCP 5-log pathogen inactivation requirements for back-sweetened wine and alcoholic apple cider.

scholarly journals Mildly Acidic pH Triggers an Irreversible Conformational Change in the Fusion Domain of Herpes Simplex Virus 1 Glycoprotein B and Inactivation of Viral Entry

2016 ◽  
Vol 91 (5) ◽  
Author(s):  
Darin J. Weed ◽  
Suzanne M. Pritchard ◽  
Floricel Gonzalez ◽  
Hector C. Aguilar ◽  
Anthony V. Nicola
Keyword(s):  
Conformational Change ◽  
Conformational Changes ◽  
Viral Entry ◽  
Low Ph ◽  
Fusion Activity ◽  
Ph Inactivation ◽  
Target Membrane ◽  
Fusion Domain ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACT Herpes simplex virus (HSV) entry into a subset of cells requires endocytosis and endosomal low pH. Preexposure of isolated virions to mildly acidic pH of 5 to 6 partially inactivates HSV infectivity in an irreversible manner. Acid inactivation is a hallmark of viruses that enter via low-pH pathways; this occurs by pretriggering conformational changes essential for fusion. The target and mechanism(s) of low-pH inactivation of HSV are unclear. Here, low-pH-treated HSV-1 was defective in fusion activity and yet retained normal levels of attachment to cell surface heparan sulfate and binding to nectin-1 receptor. Low-pH-triggered conformational changes in gB reported to date are reversible, despite irreversible low-pH inactivation. gB conformational changes and their reversibility were measured by antigenic analysis with a panel of monoclonal antibodies and by detecting changes in oligomeric conformation. Three-hour treatment of HSV-1 virions with pH 5 or multiple sequential treatments at pH 5 followed by neutral pH caused an irreversible >2.5 log infectivity reduction. While changes in several gB antigenic sites were reversible, alteration of the H126 epitope was irreversible. gB oligomeric conformational change remained reversible under all conditions tested. Altogether, our results reveal that oligomeric alterations and fusion domain changes represent distinct conformational changes in gB, and the latter correlates with irreversible low-pH inactivation of HSV. We propose that conformational change in the gB fusion domain is important for activation of membrane fusion during viral entry and that in the absence of a host target membrane, this change results in irreversible inactivation of virions. IMPORTANCE HSV-1 is an important pathogen with a high seroprevalence throughout the human population. HSV infects cells via multiple pathways, including a low-pH route into epithelial cells, the primary portal into the host. HSV is inactivated by low-pH preexposure, and gB, a class III fusion protein, undergoes reversible conformational changes in response to low-pH exposure. Here, we show that low-pH inactivation of HSV is irreversible and due to a defect in virion fusion activity. We identified an irreversible change in the fusion domain of gB following multiple sequential low-pH exposures or following prolonged low-pH treatment. This change appears to be separable from the alteration in gB quaternary structure. Together, the results are consistent with a model by which low pH can have an activating or inactivating effect on HSV depending on the presence of a target membrane.

High-Pressure Inactivation and Sublethal Injury of Pressure-Resistant Escherichia coli Mutants in Fruit Juices

1998 ◽  
Vol 64 (4) ◽  
pp. 1566-1568 ◽  
Author(s):  
Cristina Garcia-Graells ◽  
Kristel J. A. Hauben ◽  
Chris W. Michiels
Keyword(s):  
Escherichia Coli ◽  
High Pressure ◽  
Low Ph ◽  
Fruit Juices ◽  
Sublethal Injury ◽  
Ph Inactivation ◽  
Resistant Mutants ◽  
Subsequent Storage

ABSTRACT The potential of high-pressure-resistant mutants ofEscherichia coli to survive high-pressure pasteurization in fruit juices and in low-pH buffers was investigated. Treatments with up to 500 MPa of pressure caused only a limited direct inactivation of the mutants but resulted in an accelerated low-pH inactivation during subsequent storage.

Low pH Inactivation of Pectinesterase in Single Strength Orange Juice

1988 ◽  
Vol 53 (2) ◽  
pp. 504-507 ◽  
Author(s):  
J. OWUSU-YAW ◽  
M.R. MARSHALL ◽  
J.A. KOBURGER ◽  
C.I. WEI
Keyword(s):  
Orange Juice ◽  
Low Ph ◽  
Ph Inactivation

scholarly journals Rapid and Direct Effects of pH on Connexins Revealed by the Connexin46 Hemichannel Preparation

1999 ◽  
Vol 113 (5) ◽  
pp. 721-742 ◽  
Author(s):  
E. Brady Trexler ◽  
Feliksas F. Bukauskas ◽  
Michael V.L. Bennett ◽  
Thaddeus A. Bargiello ◽  
Vytas K. Verselis
Keyword(s):  
Ph Sensor ◽  
Cell Communication ◽  
Low Ph ◽  
Cytoplasmic Ph ◽  
Open Probability ◽  
Voltage Dependent ◽  
Effects Of Ph ◽  
Ph Inactivation ◽  
Cytoplasmic Side ◽  
Cell Cell

pH is a potent modulator of gap junction (GJ) mediated cell–cell communication. Mechanisms proposed for closure of GJ channels by acidification include direct actions of H+ on GJ proteins and indirect actions mediated by soluble intermediates. Here we report on the effects of acidification on connexin (Cx)46 cell–cell channels expressed in Neuro-2a cells and Cx46 hemichannels expressed in Xenopus oocytes. Effects of acidification on hemichannels were examined macroscopically and in excised patches that permitted rapid (<1 ms) and uniform pH changes at the exposed hemichannel face. Both types of Cx46 channel were found to be sensitive to cytoplasmic pH, and two effects were evident. A rapid and reversible closure was reproducibly elicited with short exposures to low pH, and a poorly reversible or irreversible loss occurred with longer exposures. We attribute the former to pH gating and the latter to pH inactivation. Half-maximal reduction of open probability for pH gating in hemichannels occurs at pH 6.4. Hemichannels remained sensitive to cytoplasmic pH when excised and when cytoplasmic [Ca2+] was maintained near resting (∼10−7 M) levels. Thus, Cx46 hemichannel pH gating does not depend on cytoplasmic intermediates or a rise in [Ca2+]. Rapid application of low pH to the cytoplasmic face of open hemichannels resulted in a minimum latency to closure near zero, indicating that Cx46 hemichannels directly sense pH. Application to closed hemichannels extended their closed time, suggesting that the pH sensor is accessible from the cytoplasmic side of a closed hemichannel. Rapid closure with significantly reduced sensitivity was observed with low pH application to the extracellular face, but could be explained by H+ permeation through the pore to reach an internal site. Closure by pH is voltage dependent and has the same polarity with low pH applied to either side. These data suggest that the pH sensor is located directly on Cx46 near the pore entrance on the cytoplasmic side.

scholarly journals Jaagsiekte Sheep Retrovirus Utilizes a pH-Dependent Endocytosis Pathway for Entry

2007 ◽  
Vol 82 (5) ◽  
pp. 2555-2559 ◽  
Author(s):  
Pascale Bertrand ◽  
Marceline Côté ◽  
Yi-Min Zheng ◽  
Lorraine M. Albritton ◽  
Shan-Lu Liu
Keyword(s):  
Leukemia Virus ◽  
Low Ph ◽  
Dominant Negative ◽  
Moloney Murine Leukemia Virus ◽  
Dominant Negative Mutant ◽  
Jaagsiekte Sheep Retrovirus ◽  
Early Entry ◽  
Ph Inactivation ◽  
Endocytosis Pathway ◽  
Ph Dependent

ABSTRACT Using Moloney murine leukemia virus pseudovirions bearing the envelope protein of Jaagsiekte sheep retrovirus (JSRV), we report here that entry was weakly inhibited by lysosomotropic agents but was profoundly blocked by bafilomycin A1 (BafA1). Kinetics studies revealed that JSRV entry is a slow process and was substantially blocked by a dominant-negative mutant of dynamin. Interestingly, a low-pH pulse overcame the BafA1 block to JSRV infection, although this occurred only if virus-bound cells were preincubated at 37°C, consistent with a very early entry event such as endocytosis being required before the low-pH-dependent step occurs. Moreover, JSRV pseudovirions were resistant to low-pH inactivation. Altogether, this study reveals that JSRV utilizes a pH-dependent, dynamin-associated endocytosis pathway for entry that differs from the classical pH-dependent entry pathway of vesicular stomatitis virus.

Relationship between golgi apparatus and axonal reticulum in sympathetic ganglion cells

1978 ◽  
Vol 36 (2) ◽  
pp. 598-599
Author(s):  
J. Quatacker ◽  
W. De Potter
Keyword(s):  
Golgi Apparatus ◽  
Sympathetic Ganglion ◽  
Phosphotungstic Acid ◽  
Ganglion Cells ◽  
Low Ph ◽  
Dense Core ◽  
Dense Core Vesicles ◽  
Large Dense Core Vesicles ◽  
Cervical Ganglia ◽  
Axoplasmic Reticulum

Mucopolysaccharides have been demonstrated biochemically in catecholamine-containing subcellular particles in different rat, cat and ox tissues. As catecholamine-containing granules seem to arise from the Golgi apparatus and some also from the axoplasmic reticulum we examined wether carbohydrate macromolecules could be detected in the small and large dense core vesicles and in structures related to them. To this purpose superior cervical ganglia and irises from rabbit and cat and coeliac ganglia and their axons from dog were subjected to the chromaffin reaction to show the distribution of catecholamine-containing granules. Some material was also embedded in glycolmethacrylate (GMA) and stained with phosphotungstic acid (PTA) at low pH for the detection of carbohydrate macromolecules.The chromaffin reaction in the perikarya reveals mainly large dense core vesicles, but in the axon hillock, the axons and the terminals, the small dense core vesicles are more prominent. In the axons the small granules are sometimes seen inside a reticular network (fig. 1).

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