scholarly journals Long-Term Storage of Vegetable Juices Treated by High Hydrostatic Pressure: Assurance of the Microbial Safety

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Justyna Nasiłowska ◽  
Barbara Sokołowska ◽  
Monika Fonberg-Broczek
Keyword(s):  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Storage Temperature ◽  
Plate Count ◽  
Bacterial Cells ◽  
Carrot Juice ◽  
Beetroot Juice ◽  
C Storage ◽  
Long Term Storage

Food business operators search for new, mild technologies, which extend the shelf life of product without changing the sensory and nutritional properties. High hydrostatic pressure (HHP) meets these requirements; however it also triggers sublethal injury of bacterial cells. Sublethal injuries could spoil the product during storage and potentially pose major public health concerns. This study aims to examine the changes of sublethally injured pathogens cells in two vegetable juices: carrot juice (pH 6.0-6.7) and beetroot juice (pH 4.0-4.2) that are induced by HHP (300-500 MPa). The possibilities of recovery of bacterial cells during 28 days of juices storage at two different temperatures (5°C and 25°C) were determined using plate count methods. During the entire period of storage of carrot juice at refrigerated temperature, the propagation and regeneration ofL. innocuastrains were observed. Storage at 25°C showed that the number of these bacteria drastically decreased between 14 and 21 days. The above phenomenon was not detected inE. colicase. There was no cells recovery during long-term refrigerated storage for all strains in beetroot juice. However, in some cases spoiling of this product intermittently occurred at 25°C storage temperature. This work demonstrates that carrot juice supports growth and regeneration of HHP-sublethally injuredL. innocua, while beetroot juice can be classified as a safe product.

scholarly journals Electrochemical Study of Enzymatic Glucose Sensors Biocatalyst: Thermal Degradation after Long-Term Storage

Chemosensors ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 53 ◽  
Author(s):  
Marcelinus Christwardana ◽  
Domenico Frattini
Keyword(s):  
Thermal Degradation ◽  
Storage Temperature ◽  
Protein Denaturation ◽  
Transfer Constant ◽  
Glucose Response ◽  
C Storage ◽  
Long Term Storage ◽  
Glucose Oxidation Reaction ◽  
Term Storage

The thermal degradation related to stability in long-term storage of a carbon nanotube-based biosensor has been investigated. The effect of storage temperature on detachment and denaturation of glucose oxidase (GOx) biocatalyst has been proved. The carbon nanotubes (CNTs) coated with polyethyleneimine (PEI) as entrapping polymer to attract more GOx to form a durable and layered CNT/PEI/GOx structure is used for long-term storage to minimize GOx detachment from the structure and minimize the possibility of enzyme and protein denaturation. After 120 days, the glucose response of the CNT/PEI/GOx biosensor stored under 4°C is preserved up to 66.7% of its initial value, while under a 25 °C storage the response is maintained up to 41.7%. The enzyme coverage activity of CNT/PEI/GOx stored at 4 °C and 25 °C has decreased by 31.1% and 51.4%, respectively. Denaturation and detachment of GOx are the common causes of thermal degradation in biosensors under improper storage temperatures, but the presence of PEI in the structure can slow-down these phenomena. Moreover, the electrons transfer constant of CNT/PEI/GOx biocatalyst stored at 4 °C and 25 °C were 7.5 ± 0.5 s−1 and 6.6 ± 0.3 s−1, respectively, indicating that also electrons mobility is damaged by detachment and denaturation of enzyme protein and the detection of glucose from the glucose oxidation reaction (GOR) is compromised.

Concurrent Effects of High Hydrostatic Pressure, Acidity and Heat on the Destruction and Injury of Yeasts

1995 ◽  
Vol 58 (3) ◽  
pp. 301-304 ◽  
Author(s):  
YOGA PANDYA ◽  
FRED F. JEWETT ◽  
DALLAS G. HOOVER
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Potato Dextrose Agar ◽  
Plate Count ◽  
Citrate Buffer ◽  
Zygosaccharomyces Bailii ◽  
Mild Heat ◽  
Yeast Cultures ◽  
Colony Forming Units

Saccharomyces cerevisiae ATCC 2373 and Zygosaccharomyces bailii ATCC 36947 were exposed to hydrostatic pressures ranging from 1,500 to 3,000 atmospheres for 10, 20 and 30 min in 0.1 M citrate buffer at pH 3.0, 4.0 and 5.0 at 25 and 45°C. Inactivation of inoculated yeast cultures was achieved in spaghetti sauce with meat at 25°C with 3,000 atmospheres for 10 min and also at 45°C and 2,500 atmospheres for 10 min. Viable counts were determined on potato dextrose agar (PDA) incubated at 30°C for 48 h. Pressure-induced injury was demonstrated by plate count differential between PDA and PDA supplemented with glucose (PDAG). A reduction of 7-log10 cycles colony forming units (CFU)/ml was seen for both strains at 3,000 atmospheres for 10 min at 25°C at all pH levels and at 2,250 atmospheres, pH 5.0 for 20 min at 45°C. At 2,000 atmospheres, pH 3.0 for 30 min, the increase in temperature from 25 to 45°C increased the inactivation of yeast by 6-log10 cycles. Lowering the pH from 5.0 to 3.0 enhanced lethality up to 2-log10 cycles at 2,250 atmospheres, 25°C for 30 min. Injury was most apparent at exposure parameters that produced 3- to 5-log10 cycle reductions on PDA. This was achieved (99% injury) at 2,250 atmospheres, 25°C for 30 min. These data indicate that mild heat and acidity contribute to the effectiveness of the inactivation and injury of yeast by high hydrostatic pressure (HHP).

scholarly journals Ribosome Reconstruction during Recovery from High-Hydrostatic-Pressure-Induced Injury in Bacillus subtilis

2019 ◽  
Vol 86 (1) ◽  
Author(s):  
Huyen Thi Minh Nguyen ◽  
Genki Akanuma ◽  
Tu Thi Minh Hoa ◽  
Yuji Nakai ◽  
Keitarou Kimura ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Growth Arrest ◽  
Recovery Process ◽  
Dependent Manner ◽  
Bacterial Cells ◽  
Vegetative Cells ◽  
Content Type ◽  
Growth Recovery

ABSTRACT Vegetative cells of Bacillus subtilis can recover from injury after high-hydrostatic-pressure (HHP) treatment at 250 MPa. DNA microarray analysis revealed that substantial numbers of ribosomal genes and translation-related genes (e.g., translation initiation factors) were upregulated during the growth arrest phase after HHP treatment. The transcript levels of cold shock-responsive genes, whose products play key roles in efficient translation, and heat shock-responsive genes, whose products mediate correct protein folding or degrade misfolded proteins, were also upregulated. In contrast, the transcript level of hpf, whose product (Hpf) is involved in ribosome inactivation through the dimerization of 70S ribosomes, was downregulated during the growth arrest phase. Sucrose density gradient sedimentation analysis revealed that ribosomes were dissociated in a pressure-dependent manner and then reconstructed. We also found that cell growth after HHP-induced injury was apparently inhibited by the addition of Mn2+ or Zn2+ to the recovery medium. Ribosome reconstruction in the HHP-injured cells was also significantly delayed in the presence of Mn2+ or Zn2+. Moreover, Zn2+, but not Mn2+, promoted dimer formation of 70S ribosomes in the HHP-injured cells. Disruption of the hpf gene suppressed the Zn2+-dependent accumulation of ribosome dimers, partially relieving the inhibitory effect of Zn2+ on the growth recovery of HHP-treated cells. In contrast, it was likely that Mn2+ prevented ribosome reconstruction without stimulating ribosome dimerization. Our results suggested that both Mn2+ and Zn2+ can prevent ribosome reconstruction, thereby delaying the growth recovery of HHP-injured B. subtilis cells. IMPORTANCE HHP treatment is used as a nonthermal processing technology in the food industry to inactivate bacteria while retaining high quality of foods under suppressed chemical reactions. However, some populations of bacterial cells may survive the inactivation. Although the survivors are in a transient nongrowing state due to HHP-induced injury, they can recover from the injury and then start growing, depending on the postprocessing conditions. The recovery process in terms of cellular components after the injury remains unclear. Transcriptome analysis using vegetative cells of Bacillus subtilis revealed that the translational machinery can preferentially be reconstructed after HHP treatment. We found that both Mn2+ and Zn2+ prolonged the growth-arrested stage of HHP-injured cells by delaying ribosome reconstruction. It is likely that ribosome reconstruction is crucial for the recovery of growth ability in HHP-injured cells. This study provides further understanding of the recovery process in HHP-injured B. subtilis cells.

Evaluation of quality changes of beetroot juice after high hydrostatic pressure processing

2017 ◽  
Vol 37 (2) ◽  
pp. 214-222 ◽  
Author(s):  
Barbara Sokołowska ◽  
Łukasz Woźniak ◽  
Sylwia Skąpska ◽  
Izabela Porębska ◽  
Justyna Nasiłowska ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Quality Changes ◽  
Beetroot Juice ◽  
High Hydrostatic Pressure Processing

Inactivation and sublethal injury ofEscherichia coliandListeria innocuaby high hydrostatic pressure in model suspensions and beetroot juice

2014 ◽  
Vol 34 (1) ◽  
pp. 147-155 ◽  
Author(s):  
Barbara Sokołowska ◽  
Sylwia Skąpska ◽  
Jolanta Niezgoda ◽  
Małgorzata Rutkowska ◽  
Agnieszka Dekowska ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Beetroot Juice ◽  
Sublethal Injury

Effect of storage temperature on spore viability and early gametophyte development of three vulnerable species of Alsophila (Cyatheaceae)

2010 ◽  
Vol 58 (2) ◽  
pp. 89 ◽  
Author(s):  
Y. Li ◽  
Y. L. Zhang ◽  
C. D. Jiang ◽  
T. Wang ◽  
Q. Wang ◽  
...  
Keyword(s):  
Liquid Nitrogen ◽  
Room Temperature ◽  
Storage Temperature ◽  
Vulnerable Species ◽  
Spore Viability ◽  
Great Loss ◽  
Gametophyte Development ◽  
Long Term Storage ◽  
Duration Of Storage

To effectively preserve the vulnerable species of Alsophila, we studied the effects of varying the temperature and duration of storage on spore viability, early gametophyte development and the microstructure of brown spores of three Alsophila species. Spores of A. spinulosa (Wall. ex Hook.) Tryon and A. gigantea Wall. ex Hook. lost viability quickly when stored at room temperature and suffered from great loss when stored at –18°C from 6 to 12 months. Within 1 month, spore viability of A. spinulosa and A. gigantea stored at 4°C was higher than that of those stored in liquid nitrogen. In contrast, long-term storage in liquid nitrogen resulted in a comparatively small loss of viability for these two species. The spores of A. podophylla Hook. died within 3 months after storage at room temperature, 4°C and –18°C, and they died within 12 months when stored in liquid nitrogen. The spores of A. spinulosa and A. gigantea stored at room temperature, 4°C and –18°C, were prone to develop into abnormal gametophytes. These results suggest that storage of A. spinulosa and A. gigantea spores in liquid nitrogen is an effective method of preserving these vulnerable species. The reasons for the failure to preserve ephemeral A. podophylla spores by storage in liquid nitrogen are discussed.

Sign in / Sign up

Export Citation Format

Share Document