315 research outputs found
Invisible Divide: Farm Workers and Telephone Accessibility
Telephones are almost universally available throughout the United States. However, farm workers and their families lack ready access to this technology. A small sample of California farm workers, vendors of telephone technology, and farm camp managers were interviewed to help understand farm worker access to and use of telephones. Results revealed a pattern of low access to and availability of telephones and major problems in the use of pre-paid phone cards. The authors argue that such communities are largely forgotten and seemingly invisible in discussions of the digital divide. Similar situations likely exist in most farm worker communities throughout the country
Shelf-life extension of watermelon juice preserved by hyperbaric storage at room temperature compared to refrigeration
This work reports Hyperbaric Storage (HS) preservation of raw watermelon juice at variable/uncontrolled
room temperature (RT,z21 C) for 7 days at 100 MPa and compared it with refrigeration (RF). At the end
of storage, there was an increase in microbial counts (total aerobic mesophiles, psychrophiles, and yeasts
and moulds) to above 6 log10 CFU/mL for samples stored at atmospheric pressure (RF and RT), while juice
stored under HS/RT showed maximum values of about 2 log10 CFU/mL for total aerobic mesophiles/
psychrophiles and below the detection limit for yeasts and moulds. HS/RT juice showed also physicochemical
parameters at levels similar to the initial juice. Thus, HS/RT can not only be used to preserve foods with no refrigeration energetic costs (since it does not require temperature control), but additionally, has also a great potential to extend the shelf-life of food products, compared to RF. This is the first case in the literature showing this additional potential/advantage of HS/RT
High pressure and thermal pasteurization effects on sweet cherry juice microbiological stability and physicochemical properties
This study evaluated high pressure processing (P1 – 400 MPa/5 min; P2 – 550 MPa/2 min) and thermal
pasteurization (TP – 70°C/30 s) effects on sweet cherry juice’s microbiological and physicochemical
parameters, during four weeks of refrigerated storage. All treatments reduced the microbiological load
to undetectable levels not affecting total soluble solids and titratable acidity. The pH increased with all
treatments, however, it decreased during storage. Phenols were differently affected: TP increased them
by 6%, P1 had no effect while P2 decreased them by 11%. During storage, phenols in control and TP
samples decreased by 26% and 20%, P1 samples decreased them by 11% whereas P2 showed no variation.
TP had no effect on anthocyanins, while pressure treatments increased them by 8%. Anthocyanins
decreased during storage, particularly in the control and P1 (decreasing 41%). All treatments had no effect
on antioxidant activity until the 14th day, thereafter high pressure processing samples showed the highest
antioxidant activity
Effect of temperature and compression/decompression rates on high pressure inactivation of Listeria
The main objective of the present study was to evaluate the effect of temperature and different compression/ decompression rates on the efficiency of Listeria inactivation by HPP.
Stationary phase cultures of Listeria innocua were subjected to 300 MPa for 5 min at 4, 10, and 20 °C using different compression and decompression rates. Inactivation was more efficient at low temperature and with lowest compression and decompression rates (1.5 MPa s–1 and 3.2 MPa s–1, respectively).
Kinetics of pressure building up and decompression, as well as temperature, have a significant impact on the outcome of Listeria inactivation by HPP. The results may contribute to the design of HPP protocols that ensure food safety, while preserving nutritional and organoleptic properties better
Food preservation under pressure (hyperbaric storage) as a possible improvement/alternative to refrigeration
Food preservation is highly dependent on refrigeration, which is limited by its high energy costs.
Among alternatives being developed, this review focused on hyperbaric storage (food preservation under pressure).
This new preservation methodology has as main objective microbial growth inhibition similarly to freezing and
refrigeration, showing a great potential to lower energy costs since refrigerated/room temperatures (RT) can be
used. This, even at variable (uncontrolled) RT (up to 37 C), has been shown to preserve foods and thus
achieving significant energy savings. Covering the earliest up to the more recent studies, this review aimed to gather information about the state of art of hyperbaric storage at refrigerated and RTs, with the primary objective of showing it potential and possible future applications of this new preservation method based on microbial growth inhibition under pressure, using pressure as the main variable to slow down microbial growth
Preservation under pressure (hyperbaric storage) at 25ºC, 30ºC and 37ºC of a highly perishable dairy food and comparison with refrigeration
Hyperbaric storage (HS) under mild pressure of requeijão, a traditional Portuguese whey cheese, as a case study of a highly perishable dairy food, was evaluated as a possible energy costless alternative to refrigeration. Whey cheese was stored for 4 and 8 hours, at different pressure levels (0.1, 100 and 150 MPa) and temperatures (25°C, 30°C and 37°C), and the results were compared with refrigeration (4°C). Microbial
analyses showed that storage for 4 hours at 100 MPa was able to maintain microbial counts similar to refrigeration and initial load, ≈3 Log10 CFU/g, at all tested temperatures. By increasing the pressure to 150 MPa and the storage time to 8 hours, microbial loads were reduced to undetectable counts, with the exception for total aerobic mesophiles that were reduced to about ≈1 Log unit. HS in general maintained pH, water activity and lipid oxidation values, at levels similar to that in refrigeration
Preservation of sliced cooked ham at 25, 30 and 37°C under moderated pressure (hyperbaric storage) and comparison with refrigerated storage
The feasibility of hyperbaric storage (HS) to substitute refrigeration as a lower energetic cost alternative to refrigeration, for sliced cooked ham preservation was assessed by using temperatures and pressures ranging 25–37◦C and 25–150 MPa for 4 and 8 h.
At microbiological level, storage at 25 ◦C, 30 ◦C, and 37 ◦C, showed no effect on microbial growth at 25 MPa reaching levels similar to atmospheric pressure storage, around 5 log CFU/g for both total aerobic mesophiles (TAM) and lactic acid bacteria (LAB). Nevertheless, the storage at 50 MPa and 30 ◦C resulted in microbial growth inhibition, resulting in TAM and LAB counts similar to refrigeration, of about 3.8 log CFU/g for both the microorganisms.
Additionally, the increase of the storage pressure to 100–150 MPa resulted in microbial inacti-vation, leading to microbial loads of almost 1 log CFU/g lower than refrigeration. In general, hyperbaric stored sliced cooked ham showed physicochemical parameters similar to the refrigerated samples.
In conclusion, these results show that HS at uncontrolled (naturally variable room tem-perature conditions at 25–37 ◦C) is a promising alternative to refrigeration for cooked ham preservation. To this new preservation technology, no energetic costs are associated throughout storage, compared to refrigeration, needing only energy to generate the pressure and decompress, since no energy is required to maintain the pressure
Preservation of a highly perishable food, watermelon juice, at and above room temperature under mild pressure (hyperbaric storage) as an alternative to refrigeration
The feasibility of food preservation under pressure (hyperbaric storage) at and above room temperatures,
as an alternative to refrigeration was evaluated. Preservation of a highly perishable food, watermelon
juice, was studied at pressures of 25e150 MPa and temperatures ranging 20e37 C, being compared to
refrigeration and storage at atmospheric pressure at the same temperatures.
Hyperbaric storage at 75 MPa (20e37 C) revealed an inhibitory effect on microbial growth, with at
least an equal performance compared to refrigeration. An additional inactivation effect was verified for
storage at 100 and 150 MPa, with reduction of the initial microbial counts to 1.00 Log CFU/mL for
enterobacteriaceae and yeasts and moulds, and from 4.43 ± 0.04 to 3.31 ± 0.04 and 2.99 ± 0.07 Log CFU/
mL, respectively, for total aerobic mesophiles (25 C).
In general, pH, titratable acidity and total soluble solids did not show a clear variation trend with
pressure and no considerable differences among storage conditions were verified. Cloudiness decreased
for samples stored under pressure and browning degree was in general lower in samples stored under
pressure compared to refrigeration.
This work demonstrates the potentiality of hyperbaric storage as a new preservation methodology, at
variable (uncontrolled) room temperature without energetic costs during storage, as an alternative to
refrigeration
13C solid-state nuclear magnetic resonance and Fourier transform infrared studies of the thermal decomposition of cork
The thermal decomposition of cork has been studied by Fourier transform infrared (FTIR) spectroscopy and 13C
solid-state nuclear magnetic resonance (NMR) spectroscopy with cross-polarization and magic-angle spinning
(CP-MAS), high-power ‘H decoupling (HPDEC) and cross-polarization depolarization-polarization (CPDP). Waxes
and other soluble components of cork begin to decompose at ca. 150°C. This is accompanied by partial decomposi tion of suberin, probably initiated at the points of attachment to the cell wall. The carbohydrates begin to decompose
at ca. 200°C. The decomposition of lignin begins at 250-3OO”C, while suberin undergoes further degradation.
Significant amounts of coke are formed in the process. At 400°C cork has been transformed into coke with traces of
partially decomposed suberin. The thermal decomposition of cork is dependent on the calcination time, particularly
in the 200-350°C range.info:eu-repo/semantics/publishedVersio
Probing the fuzzy sphere regularisation in simulations of the 3d \lambda \phi^4 model
We regularise the 3d \lambda \phi^4 model by discretising the Euclidean time
and representing the spatial part on a fuzzy sphere. The latter involves a
truncated expansion of the field in spherical harmonics. This yields a
numerically tractable formulation, which constitutes an unconventional
alternative to the lattice. In contrast to the 2d version, the radius R plays
an independent r\^{o}le. We explore the phase diagram in terms of R and the
cutoff, as well as the parameters m^2 and \lambda. Thus we identify the phases
of disorder, uniform order and non-uniform order. We compare the result to the
phase diagrams of the 3d model on a non-commutative torus, and of the 2d model
on a fuzzy sphere. Our data at strong coupling reproduce accurately the
behaviour of a matrix chain, which corresponds to the c=1-model in string
theory. This observation enables a conjecture about the thermodynamic limit.Comment: 31 pages, 15 figure
- …