This study evaluated the effect of subcritical water (SW) hydrolysis to convert meat proteins into bioactive ingredients. Pork loin was selected as a model meat source and hydrolyzed at temperatures ranging from 100 °C to 300 °C and compared with those obtained via enzymatic hydrolysis (EH). SW treatments above 200 °C enhanced protein recovery and free amino group content relative to EH treatment, with the highest protein recovery observed at 300 °C. Hydrolysates produced at temperatures above 250 °C exhibited strong antioxidative and ACE inhibitory activities without evidence of cytotoxicity. However, probiotic strain growth was inhibited and bitterness increased at temperatures above 250 °C. SW treatments below 250 °C showed reduced bitterness and higher umami intensity relative to EH treatments. The findings of this study indicated that SW treatment at 250 °C resulted in high protein recovery, strong bioactivities and favorable taste attributes, representing a promising strategy for the conversion of pork loin proteins into high-value food ingredients.

The long-term transportation of kimchi causes excessive fermentation, leading to packaging expansion or bursting. A novel strategy was hypothesized: the frozen export of kimchi Yangnyeom sauce alone, with subsequent kimchi preparation at the destination. Carrageenan, inulin, trehalose, and maltodextrin were incorporated to mitigate lactic acid bacteria (LAB) viability loss during long-term frozen storage, with physicochemical and microbial properties analyzed during 24 weeks of storage at −18°C (frozen) and 4°C (refrigerated). During refrigerated storage, LAB populations rapidly increased, accompanied by a decrease in reducing sugar content and a rise in titratable acidity after eight weeks – refrigeration is unsuitable for long-term distribution. Conversely, frozen storage resulted in a gradual decline in reducing sugars and a slower increase in titratable acidity. Cryoprotectant supplementation mitigated the reduction in LAB during frozen storage. Trehalose alleviated the decrease in reducing sugar and LAB counts. Inulin and maltodextrin accelerated fermentation, probably because of their prebiotic activities – they are unsuitable for long-term storage. Carrageenan exhibited negligible effects at all tested concentrations. The findings suggest the feasibility of frozen storage and long-term distribution of kimchi Yangnyeom sauce supplemented with trehalose. Future research should evaluate the quality of kimchi prepared using stored sauces and assess applicability under export conditions.

This study evaluated the feasibility of using frozen kimchi sauce prepared with cryoprotectants (Car: carrageenan and Tre: trehalose) for long-term distribution and subsequent production. Kimchi quality correlated with kimchi sauce quality. Kimchi yangnyeom sauces were prepared with or without cryoprotectants and stored under refrigerated (4°C, R) or frozen (−18°C, F) conditions for up to 24 weeks. At each storage interval, freshly salted kimchi cabbage (brined in 15% NaCl for 7 h) was mixed with the stored sauces to manufacture kimchi, which was fermented at 4°C until analysis. The titratable acidity of all kimchi remained below the optimal ripening threshold (0.7–0.9%) until 4 weeks of storage. Conversely, all kimchi had pH levels below optimal ripening criterion (pH of 4.2–4.5) following 12 weeks of storage. At 8th week, CarR, TreR, and TreF approached optimal ripening considering both pH and titratable acidity simultaneously. TreF exhibited the highest reducing sugar concentration (p < 0.05). Control and Car group kimchi had lower reducing sugar concentrations. Total aerobic and lactic acid bacteria exhibited a typical kimchi fermentation trend, with no significant microbiological differences among kimchi sauces. Thus, frozen storage of trehalose-prepared kimchi sauce may help preserve fermentation stability during long-term distribution.

This study investigated the feasibility of a continuous subcritical water (CSW) system for efficient biomass valorization and compared its performance with that of a conventional batch system using the severity index (SI; log R-0). In comparative 3% sucrose hydrolysis, the CSW system achieved maximum glucose and fructose yields at a significantly lower SI (log R-0 = 5.0) than the batch system (log R-0 = 7.1) (p < 0.05) due to precise residence time control. At high temperatures (>250 degrees C), the batch system induced hydrothermal gasification as a distinct degradation pathway, converting hydrolyzed sugars into insoluble solids (char). However, the CSW system effectively suppressed terminal decomposition, stably preserving thermal derivatives such as acids and 5-hydroxymethylfurfural (5-HMF) in the liquid phase. Independent adiabatic compression heating experiments were conducted to suppress uncontrolled hydrolysis and achieve efficient CSW heating. The experiments elucidated the temperature increase (Delta T) as a function of the initial sample temperature (T-i), and a polynomial regression model was derived to validate a rapid heating control strategy. Based on the sucrose hydrolysis model, this study suggests that the CSW system using adiabatic compression is an effective processing strategy for maximizing sucrose hydrolysate recovery by eliminating unnecessary severity and effectively suppressing terminal decomposition.

This study investigated the effects of combining sous vide (SV) and high-pressure (HP, 0.1–200 MPa) on the structural changes of meat proteins and the eating quality of pork loin in comparison to commercial cooking (CC). Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy showed that SV under HP stabilized the secondary structure of sarcoplasmic proteins. SV under HP treatments significantly reduced cooking loss and improved water-retention ability. Texture profile analysis (TPA) showed that SV under HP reduced the hardness and chewiness while increasing springiness. Instrumental color analysis revealed that SV under 200 MPa resulted in higher L* and a* values with a lower b* value than SV-AT (p < 0.05). These findings demonstrated that SV cooking under HP was a promising cooking method for enhancing the eating quality of pork loin, potentially expanding the utilization of lean cuts, which are generally less favored by consumers.

Sea lettuce (Ulva prolifera) has become a coastal pollutant despite its benefits for human health. This study investigated the effect of subcritical water (SW) liquefaction on the changes in the composition and physiological activities of sea lettuce. Proteins and polysaccharides from sea lettuce were hydrothermally hydrolyzed with SW at 200-250 degrees C, and these hydrolysates underwent Maillard reaction, yielding a maximum amount of melanoidin at 250 degrees C. The SW at 250 degrees C was effective for the extraction of phenolic compounds from sea lettuce. 2,2 '-Azino- bis-(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS) radical inhibition activity and angiotensin-converting enzyme (ACE) inhibition activity indicated that the thermochemical changes induced by SW enabled the conversion of sea lettuce into strong antioxidative and antihypertensive biomaterials. Sea lettuce subjected to a temperature of 150 degrees C exhibited the best prebiotic activity, whereas lettuce liquefied at 300 degrees C showed strong antimicrobial activity. The taste profiles of sea lettuce indicated that the simple taste attribute of the control extract was transformed into a complex taste attribute through SW. In particular, sea lettuce subjected to 250 degrees C had the highest sweetness and umami. Consequently, this study demonstrated that sea lettuce liquefied by SW could be used as a biomaterial and a taste enhancer in food systems, and the SW had notable potential for the upcycling utilization of sea lettuce in the functional food industry.

Pretreatments, including heating or freezing for the handling of restructured meat, can cause quality deterioration during cooking due to excessive drip loss. This study investigated the effects of high-pressure (HP) processing (200 MPa for 15 min), cooking methods, and freezing on the quality characteristics of moisture-enhanced restructured pork (MERP). The MERP was formulated to 84% moisture and compared with a control with 74% moisture. The MERP was applied to conventional cooking (75°C for 30 min) and sous-vide cooking (55°C for 24 h), and parts of sous-vide cooked MERP were frozen at -30°C for 24 h to assess quality deterioration. Results revealed that HP cooking effectively bound meat cubes in MERP, and further cooking enhanced the binding strength of MERP products. During cooking, sous-vide improved the moisture retention of MERP. However, freezing increased the cooking loss of MERP, particularly of frozen and reheated MERP, which exhibited the highest cooking loss among the treatments. Despite the fact that the moisture loss of freezing treatments negatively affected the tenderness of the MERP products, frozen MERP retained a tender texture compared with the unfrozen control. HP combined with sous-vide cooking rarely affected the cooked color of MERP, and the MERP products exhibited normal cooked color of meat products. Therefore, the present study indicated that HP and sous-vide cooking improved the quality characteristics of MERP, which suggested that MERP could achieve better consumer preference than typically manufactured restructured meat products.

Ready-to-eat sliced prosciutto samples were treated with ultraviolet (UV) light (wavelength: 265 and 275 nm/intensity: 10 and 50 mW) after inoculation with hepatitis E virus (HEV), Escherichia coli O157:H7, or Listeria monocytogenes. The parameters of prosciutto quality assessed were color, texture, pH, water content, water holding capacity, oxidative rancidity, and freshness. The prosciutto sample under UV-C light was influenced on changes of color, lipid oxidation, and protein oxidation due to free radical generation. UV-C light reduced E. coli O157:H7 and L. monocytogenes counts by up to 2.23 Log and 1.85 Log colony forming units/g, respectively. The amount of HEV was also significantly reduced after treatment (p<0.05). HEV was no longer detected after 10 min of treatment at an intensity of 50 mW. Consequently, UV-C treatment above 265 nm at 50 mW for 10 min is an effective strategy for maintaining product quality and improving food safety. The results of this study advance the application of non-thermal food preservation.

This study investigated the effects of sea lettuce (SL, Ulva prolifera) extracted using various subcritical water (SW) temperatures (100°C-300°C) on the physicochemical properties of pork patties. The thiobarbituric acid reactive substances and total volatile basic nitrogen of patties prepared with SL extracted at ≥200°C were significantly lower than those of the control after 2 weeks of chilled preservation (p<0.05). In addition, the extracts subjected to ≥250°C exhibited lower total aerobic microbial count than the control (p<0.05). Although the brownish appearance originating from the SL extracts influenced the color of the pork patties, the patties containing SL extracted at temperatures of ≥200°C maintained a stable color even after preservation. The water-binding properties of the patties tended to increase as the extraction temperature of SL increased, and the extracts obtained at temperatures of 200°C-250°C exhibited texture characteristics similar to the fresh group after preservation. Although the optimal SW extraction temperature for SL in relation to the physicochemical properties of the patties was not distinguished, SL extracted at temperatures of 200°C-250°C generally demonstrated potential as an additive for extending the freshness of pork patties. Consequently, the results of this study revealed that SL extracted at 200°C-250°C effectively inhibited the oxidative deterioration of the patties.

This study examined the effects of subcritical water (SW) extraction on the compositional and physiological changes in spent coffee grounds (SCG). SW at 250 degrees C effectively reduced the residual solid content in SCG. However, Maillard interactions limited protein recovery from SCG, and SCG extracted at a temperature greater than 250 degrees C exhibited lower angiotensin-converting enzyme (ACE) inhibitory activity compared with those extracted at a temperature below 200 degrees C, indicating that the bioactivities of the SCG extracts were depended on the applied SW temperature. The SCG extracted at lower than 200 degrees C exhibited prebiotic potential for Lactobacillus rhamnosus GG (LGG) and Enterococcus faecium, whereas those extracted at greater than 250 degrees C demonstrated an antimicrobial ability toward the probiotic strains owing to the production of thermal derivatives of sugars such as acids and 5-hydroxymethylfurfural (HMF). The temperature-dependent thermochemical changes in SCG afforded a complex taste profile with less bitterness. Therefore, this study revealed that SW had the potential to convert coffee byproducts into useful food ingredients.

Background:Subcritical water (SW) is regarded as an effective conversion technology for lignocellulosic biomass. The effect of SW on ginseng are limited to evaluate the ginsenoside composition of red ginseng, and there is little information on the effects of SW on fresh ginseng. Methods:The general characteristics of ginseng extracts (GE) prepared with SW were evaluated in terms of brix, reducing sugar and residual solid content, and compositions of GE was estimated using chromatography. For utilization of GE as a bioactive food, the ginsenoside composition, antioxidative activity, angiotensin-converting enzyme (ACE) inhibitory activity, prebiotic potential and taste attributes were measured. Results:Increasing SW temperature decreased residual solid content of ginseng and the soluble compounds of GE were yielded by SW at 250 °C. Despite that ginsenoside content decreased with SW temperature, a steep increase in Rg5 was observed at 200 °C. The SW at 200-250 °C manifested the highest antioxidant activities and ACE inhibitory activity of GE. However, the GE prepared at greater than 250 °C completely lost prebiotic potentials. Based on electronic-tongue, umami taste was enhanced by SW at 200 °C, but sweetness and bitterness were dominated at 250-300 °C. Conclusion:The results demonstrated that SW has a potential application to convert lignocellulosic wastes generated from ginseng roots into bioactive food resource, and SW at ∼200 °C can be potentially used to enhance the physiological activities of GE.

Kimchi products are often discarded by burst package due to the excessive fermentation during long-term distribution. In this study, supercooling storage was approached to prevent deterioration during distribution by regulating fermentation rate and maintaining quality of products by lowering storage temperature. Herein, cut cabbage kimchi (CCK) products were stored in the supercooling condition by stepwise temperature control algorithm for 12 weeks. During storage, the temperature of CCK was strictly followed the algorithm, maintaining -3.5°C at the lowest step without ice nucleation. The supercooled CCK were reduced in the LAB growth comparing to the refrigerated CCK, presenting superior quality. Further, heterofermentative LABs were dominant in supercooled CCK after 12 weeks, maintaining the earlier stage of fermentation. Reversely, homofermentative LABs were dominant in refrigerated CCK, meaning the latter stage of fermentation. Freezing suppressed the growth of aerobic bacteria and LAB in CCK and lost the physicochemical qualities by damages from freezing and thawing. Thus, supercooling storage could help maintain the original qualities of CCK to control fermentation rate at -3.5°C for long-term storage in the static condition. Further studies can be conducted at -3.5°C reflecting practical conditions.

Ready-to-eat sliced prosciutto samples were treated with ultraviolet (UV) light (wavelength: 265 and 275 nm/intensity: 10 and 50 mW) after inoculation with hepatitis E virus (HEV), Escherichia coli O157:H7, or Listeria monocytogenes. The parameters of prosciutto quality assessed were: color, texture, pH, water content, water holding capacity, oxidative rancidity, and freshness. The prosciutto sample under UV-C light was influenced on changes of color, lipid and protein oxidation, and protein oxidation due to free radical generation. UV-C light reduced E. coli O157:H7 and L. monocytogenes counts by up to 2.23 Log and 1.85 Log colony forming units/g, respectively. The amount of HEV was also significantly reduced after treatment (p<0.05). HEV was no longer detected after 10 min of treatment at an intensity of 50 mW. Consequently, UV-C treatment above 265 nm at 50 mW for 10 min is an effective strategy for maintaining product quality and improving food safety. The results of this study advance the application of non-thermal food preservation.

Supercooling is the method of lowering the temperature of a foodstuff below its freezing point without phase transitions. This storage technique has a potential advantage for extending shelf life. Nevertheless, the supercooled state of food is thermodynamically unstable. To accomplish supercooling storage, slow cooling rate and minimized temperature fluctuation are necessary. Thus, a stepwise cooling algorithm was designed and applied in this study. Pork belly and chicken breast were stored at 3 °C, −18 °C (freezing), and supercooling treatment was applied to them for 12 days. All samples preserved their supercooled state and were unfrozen during the storage period. Overall, supercooled samples were advantageous in respect of drip loss compared to that of frozen samples, regardless of type of sample. Total volatile basic nitrogen, total aerobic account, and cooking loss of pork belly was higher than in the chicken breast due to the high fat retention in pork belly as compared to chicken breast, in particular, at refrigerated storage condition. Samples stored at supercooling treatment prevented increase in volatile basic nitrogen and microbial growth. Therefore, the supercooled state was successful when using stepwise algorithm, and it was effective at maintaining meat quality compared to freezing and refrigeration storage.

Abstract Supercooling storage refers to lowering the product temperature below its freezing point without phase transition and has the potential to extend shelf life. Nevertheless, supercooled objects are in a thermodynamically unstable state, and nucleation can occur spontaneously. To achieve supercooling storage, slow cooling and insulation are essential. Hence, a stepwise algorithm for the supercooling storage of pork loins was designed and validated in this study. Pork loins were stored at 3°C, −18°C, and −3°C (freezing), and supercooled for 16 days. All samples remained in a supercooled state and were unfrozen at the end of storage. Supercooled pork loins were superior in terms of drip loss, cooking loss, and water-holding capacity compared to frozen samples. Additionally, supercooling treatment prevented discoloration, increase of volatile basic nitrogen, and microbial growth. Thus, supercooling of pork loin was achieved using a stepwise program and was effective to maintain meat quality.

Supercooling storage reduces the temperature of a product by lowering its freezing point without phase tran-sition and may extend its shelf life. However, it is difficult to maintain the supercooled state of food as it is thermodynamically metastable. A slow cooling rate and minimal fluctuation are essential for achieving stable supercooling storage. Therefore, a stepwise algorithm was adopted for supercooling storage in this study. Salmon and olive flounder were stored at 3 degrees C (refrigeration),-18 degrees C (freezing), and-2 degrees C (supercooling) for 12 days. Samples were maintained in a supercooled state and unfrozen during the storage period. Samples stored after the supercooling treatment were superior with respect to drip loss and water holding capacity (WHC) compared to frozen samples, regardless of the type of sample. WHC and total volatile basic nitrogen values of olive flounder was higher than those in salmon owing to the higher water and protein content in olive flounder than in salmon. Moreover, the supercooled samples inhibited the increase in trimethylamine and volatile basic nitrogen levels. Microbial growth was slow. Thus, a stepwise algorithm for stable supercooled storage was achieved, which effectively preserved fish quality better than freezing and refrigeration storage.

The effects of long-term deep freezing and standard storage temperatures on mackerel and croaker qualities were evaluated. Fishes were packed in air-containing packages and stored at -60 degrees C, -50 degrees C, and -18 degrees C for six months. Drip losses of the thawed deep-frozen fishes (-60 degrees C) were lowest throughout the storage period (p< .05), whereas the WHC values were the highest (p<.05), and TBARS and TVBN levels were the lowest (p< .05). Consequently, these fishes were regarded as fresher than those stored at -50 degrees C and -18 degrees C, making this temperature desirable for maintaining mackerel and croaker quality during long-term storge.

This study investigated the effect of supercooling preservation on the freshness and quality parameters to mackerel in comparison to chilled (refrigerated) and freezing condition. Stepwise cooling by 0.5 degrees C every 18 h was applied to preserve mackerel under a supercooled state for 12 days, and physicochemical properties were compared with chilled and frozen samples. The mean preservation temperatures (Tm) were 1.01 degrees C, -1.42 degrees C and -17.5 degrees C for the chilled, supercooled and frozen treatments, respectively. Freshness parameters indicated that supercooling effectively delayed both oxidative and microbial deteriorations, including total aerobic count (TAC), thiobarbituric acid reactive substances (TBARS), total volatile basic nitrogen (TVBN) and trimethylamine (TMA), compared to chilled conditions. Based on kinetic analysis, the freshness holding period of supercooled mackerel was 9.51 days compared to 4.53 days of chilled mackerel. Although oxidative discoloration could not be prevented by supercooled preservation, supercooled mackerel showed better water-binding and textural properties than chilled or frozen mackerel after 12 days of storage. From the results, supercooling was effective to maintain fresh conditions (sashimi or sushi grade) of mackerel for more than twice the duration of chilled preservation.

In this study, spray-dried double emulsion loaded bromelain was applied to Japanese Spanish mackerel fillets to develop fish-type, elderly-friendly foods. Japanese Spanish mackerel, treated with spray-dried double emulsions, were stored at 4°C for 24 h. For the characterization of emulsion particles, the particle size, ζ-potential, and morphology were determined. The color, TBARS, VBN, TMA, hardness, and adhesiveness of fish fillets treated by emulsion were measured for physicochemical properties. All the particle sizes of spray-dried emulsion were decreased while their double emulsion structure was maintained. Spray-dried emulsion reduced the color difference of fish fillets and did not catalyze lipid oxidation and protein decomposition. Values of TBA, VBN, and TMA of all fish did not exceed 0.5 mg MDA/kg, 30 mg/100 g, and 10 mg/100 g, respectively, which are considered edible limits regardless of bromelain or emulsion application. Bromelain modified fish fillets' hardness and adhesiveness to be suitable for elderly food, although it was encapsulated in the emulsion. Thus, spray-dried fish oil W/O/W double emulsion-loaded bromelain can be applied as a fish tenderizer, and this study’s results can be utilized to develop elderly-friendly food.

As storage temperature impacts frozen meat quality, we evaluated the ideal freezing and storage temperatures for pork loin, and effects of long-term storage at − 60, − 50, and − 18 °C on pork loin physicochemical properties. Pork loin was cut into 30 × 30 × 30 mm (50 g) and packed in air-containing box. Thereafter, they were stored at different freezing temperature for 6 months. Frozen pork loins were thawed at 4 °C. Samples frozen at − 18 °C exhibited surface dehydration (at 3 months) and high moisture loss surface dehydration-induced discoloration and toughening. However, samples frozen by deep freezing temperature (− 60 and − 50 °C) had lower values of thawing loss, WHC, and shear force than those of frozen at − 18 °C. Samples frozen at − 60 and − 50 °C maintained their freshness better than those frozen at − 18 °C; samples stored at − 60 °C showed significantly lower VBN than those stored at − 50 °C. Therefore, − 60 °C is suitable for freezing pork loins.