• Korean Journal of Poultry Science
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• v.41 no.3
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• pp.159-164
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• 2014

This study was conducted to investigate whether water chilling had effect on water retention, freshness or internal temperature of chicken carcasses during chilling or storage in two different chicken processing plants (designated as A and B). A total of 240 carcasses from chicken processing plants (n = 120 per chicken processing plant) was randomly sampled and evaluated the effect of water chilling on carcass characteristics (i.e., water retention, water loss or freshness during chilling or storage). Torrymeter value was used as an indicator of freshness in chicken carcasses. Water chilling did not affect carcass water retention between the processing plants. However, chicken carcasses processing in B plant exhibited significantly higher freshness (p<0.05) compared with those in A plant. This difference in freshness was mainly due to the longer transit time through the water chiller in A versus B plants. Water loss of carcasses during storage was not different between plants. It was found that carcass freshness can be affected by water chilling time as manifested in this study. Further study is warranted to see whether freshness or microbiological status of chicken carcasses may be affected depending on the chilling methods, i.e., air or water chilling.

• Clinical Nutrition Research
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• v.5 no.3
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• pp.172-179
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• 2016

Acid food indicators can be used as pH indicators for evaluating the quality and freshness of fermented products during the full course of distribution. Iron oxide particles are hardly suspended in water, but partially or completely agglomerated. The agglomeration degree of the iron oxide particles depends on the pH. The pH-dependent particle agglomeration or dispersion can be useful for monitoring the acidity of food. The zeta potential of iron oxide showed a decreasing trend as the pH increased from 2 to 8, while the point of zero charge (PZC) was observed around at pH 6.0-7.0. These results suggested that the size of the iron oxide particles was affected by the change in pH levels. As a result, the particle sizes of iron oxide were smaller at lower pH than at neutral pH. In addition, agglomeration of the iron oxide particles increased as the pH increased from 2 to 7. In the time-dependent aggregation test, the average particle size was 730.4 nm and 1,340.3 nm at pH 2 and 7, respectively. These properties of iron oxide particles can be used to develop an ideal acid indicator for food pH and to monitor food quality, besides a colorant or nutrient for nutrition enhancement and sensory promotion in food industry.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.3
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• pp.427-432
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• 2005

The purpose of this study was performed as model study using four animals to investigate the correction between the changes in Differential Scanning Calorimetry thermogram of muscle proteins during storage and meat freshness. M. longissimus dorsi of pork was obtained immediately after slaughter and chilled/stored at either $-2^{\circ}C$ or $25^{\circ}C$ for up to 96 h for analyses. DSC thermograms were determined and compared with pH values, ATP-related compounds, K-values, volatile basic nitrogen (VBN) levels, bacterial counts and electrophoretic behavior. Changes in pH, bacterial counts, VBN and K-values were associated with increased storage temperature and time. The levels of pH values, bacterial counts, VBN and K-values of pork samples stored at $25^{\circ}C$ were higher than those of the pork samples stored at $-2^{\circ}C$. ATP concentration decreased faster in samples stored at $25^{\circ}C$. Only IMP increased in samples stored at $-2^{\circ}C$, whereas the concentration of hypoxanthine and inosine increased in samples stored at $25^{\circ}C$. One exothermic peak and two endothermic peaks appeared on the thermograms of pork stored at either temperature. Lower transition temperature of myosin, sarcoplasmic protein and actin peaks were observed. The freshness parameters of K-value, VBN and hypoxanthine showed highly negative correlations (-0.742- -0.9980) to the changes in transition temperature. Therefore, the shift temperature on DSC thermogram can be used as an indicator of the freshness parameters of meat.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.6
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• pp.735-739
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• 2019

The purpose of this study was to measure pH, trimethylamine (TMA), and total volatile basic nitrogen (TVB-N) as indicators of freshness during largehead hairtail Trichiurus lepturus storage, and to compare these indicators with those obtained by the sensory evaluation of quality index method (QIM) sensory evaluation. Largehead hairtail samples were stored at 4℃ and evaluated every 3 days until decay. The QIM sensory evaluation indicated scores of 0, 8.9, and 20 on storage days 0, 6, and 20, respectively. By day 15, the samples were completely decayed. The pH slowly increased during the storage period, reaching a maximum of 7.4. In the day 6, TMA and TVB-N contents were 2.97 and 15.57 mg/100 g, respectively. Thus, at 4℃, the largehead hairtail starts to decay after 6 days and, after 9 days, cannot be consumed safely

• Food Science and Preservation
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• v.18 no.6
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• pp.824-829
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• 2011

This study was conducted to identify quality indicators to determine freshness of muskmelon during distribution. The correlation between each quality characteristic and organoleptic preference was analyzed after examining weight loss, firmness, soluble solid content, chromaticity, and respiration rate of and changes in the organoleptic characteristics during storage at 0, 10, 20 and $30^{\circ}C$ after harvesting. The correlation between weight loss and preference according to the storage temperature was shown to be significant (p<0.01). The correlation between firmness and preference was shown to be highly significant (R=0.74, 0.78, 0.88, and 0.83 at 0, 10, 20, and $30^{\circ}C$) under all temperature conditions, and was shown to be especially highly significant (p<0.01) when the temperature was high. In the case of storage at 20 and $30^{\circ}C$, a significant correlation between soluble-solid content and preference was shown. Therefore, it is right to apply the change in weight loss and firmness that indicated a high correlation with organoleptic preference as a quality indicator at all storage temperatures.

• Journal of Sensor Science and Technology
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• v.29 no.2
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• pp.93-99
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• 2020

A colorimetric paper sensor was used to detect volatile nitrogen-containing compounds emitted from spoiled salmon filets to determine their freshness. The sensing mechanism was based on acid-base reactions between acidic pH-indicating dyes and basic volatile ammonia and amines. A sensing layer was simply fabricated by drop-casting a dye solution of bromocresol green (BCG) on a polyvinylidene fluoride substrate, and its color-change response was enhanced by optimizing the amounts of additive chemicals, such as polyethylene glycol, p-toluene sulfonic acid, and graphene oxide in the dye solution. To avoid the adverse effects of water vapor, both faces of the sensing layer were enclosed by using a polyethylene terephthalate film and a gas-permeable microporous polytetrafluoroethylene sheet, respectively. When exposed to basic gas analytes, the paper-like sensor distinctly exhibited a color change from initially yellow, then to green, and finally to blue due to the deprotonation of BCG via the Brønsted acid-base reaction. The use of ammonia analyte as a test gas confirmed that the sensing performance of the optimized sensor was reversible and excellent (detection time of < 15 min, sensitive naked-eye detection at 0.25 ppm, good selectivity to common volatile organic gases, and good stability against thermal stress). Finally, the coloration intensity of the sensor was quantified as a function of the storage time of the salmon filet at 28℃ to evaluate its usefulness in monitoring of the food freshness with the measurement of the total viable count (TVC) of microorganisms in the food. The TVC value increased from 3.2 × 10⁵ to 3.1 × 10⁹ cfu/g in 28 h and then became stable, whereas the sensor response abruptly changed in the first 8 h and slightly increased thereafter. This result suggests that the colorimetric response could be used as an indicator for evaluating the degree of decay of salmon induced by microorganisms.

• Journal of Microbiology and Biotechnology
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• v.26 no.4
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• pp.648-658
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• 2016

Preservation of fresh algae plays an important role in algae seed subculture and aquaculture. The determination and examination of the changes of cell viability, composition, and bacterial species during storage would help to take suitable preservation methods to prolong the preservation time of fresh algae. Nostoc flagelliforme is a kind of edible cyanobacterium with important herbal and dietary values. This article investigated the changes of bacterial species and biochemical characteristics of fresh N. flagelliforme concentrate during natural storage. It was found that the viability of cells decreased along with the storage time. Fourteen bacteria strains in the algae concentrate were identified by PCR-DGGE and were grouped into four phyla, including Cyanobacteria, Firmicutes, Proteobacteria, and Bacteroidetes. Among them, Enterococcus viikkiensis may be a concern in the preservation. Eleven volatile organic compounds were identified from N. flagelliforme cells, in which geosmin could be treated as an indicator of the freshness of N. flagelliforme. The occurrence of indole compound may be an indicator of the degradation of cells.

• Journal of Biosystems Engineering
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• v.33 no.4
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• pp.239-247
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• 2008

Firmness is very important factor to evaluate the freshness and ripeness among the various factors, in concerning about the melon quality. This study was carried out to develop the technique using impact signal to measure the melon firmness nondestructively. Results of analyzing impulse signals of melons having different firmness levels showed that the firmness of melon affected various impulse responses including amplitude, transmitted time, maximum peak frequency, firmness index 1 ($f^2m$), and firmness index 2 ($f^2m^{2/3}$). Impulse signal amplitude was the best indicator to predict the firmness of melon because of a strong corelation ($R^2\;=\;0.9071$). Firmness index 1, firmness index 2, maximum peak frequency, and normalized transmitted time were also possible indicators with acceptable correlation values.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.2
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• pp.294-300
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• 2010

This experiment was conducted to investigate the effects of Opuntia humifusa (OPH) extracts and methyl sulfonyl methane (MSM) supplementations on the laying productivity, egg quality and sensory characteristics of eggs in hens. Six hundred forty, 35-wk-old Lohmann brown, laying hens were randomly divided into four groups: 1) water (control), 0.12% OPH extract, 0.1% MSM, and 0.12% OPH extract+0.1% MSM. They were mixed into the feed and given for 5 weeks. Egg production rates, egg weight, feed demand ratio were not significantly different among the groups. However, OPH or MSM decreased broken egg rates by increasing thickness and firmness of egg shell but they did not show the additive effects. In addition, OPH or MSM enhanced Haugh unit, an indicator of freshness of egg, and viscosity of egg white and egg yolk. OPH or MSM maintained the freshness of eggs better the control during their storage for 10 day at $4^{\circ}C$. However, OPH+MSM did not show additive effects in their freshness. Sensory test revealed that OPH or MSM decreased fishy taste and greasy flavor and they improved texture. Overall OPH or MSM enhanced the preference of eggs. In conclusion, the supplementation of either OPH or MSM enhances egg freshness and egg quality in laying hens but they should not be supplemented together due to no additive effects.

• Food Science and Preservation
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• v.21 no.5
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• pp.609-617
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• 2014

This study was conducted to identify quality indicators of the freshness of chicken eggs circulating in domestic markets. We first stored freshly-laid eggs at temperatures of 0, 10, 20, and $30^{\circ}C$, investigated their weight-loss rate, specific gravity, color, york index, albumen index, Haugh unit (HU), pH, and sensory evaluation, and finally analyzed the correlation between each quality characteristic and the sensory preference. At all the storage temperatures, the quality characteristics of the weight-loss rate, specific gravity, yolk index, albumen index, and HU showed significant correlations (p<0.05) with the preference. In particular, the temperature-dependent correlation between the quality characteristics and the sensory preference was significantly higher with increasing storage temperatures and weight-loss rates (r = -0.78; r = -0.93; r = -0.95; and r = -0.99), albumen index (r = 0.66; r = 0.89; r = 0.89; and r = 0.93), and HU values (r = 0.64; r = 0.92; r = 0.96; and r = 0.98) at 0, 10, 20, and $30^{\circ}C$, respectively (p<0.01). The Color and pH examinations yielded disparate results, and further research is needed to determine the methods of using the characteristics as quality indicators. We believe that the changes in the weight-loss rate, specific gravity, yolk index, albumen index, and HU are adequate quality indicators of the freshness of egg in circulation.