Effect of Mollusca shell extracts on inhibition of kimchi over-acidification.

Mollusca species shell such as oyster shell (OS) and snail shell (SS), are discarded after taking the meat, and the discarded shell causes the environmental problems. Therefore, recycling shell waste could potentially eliminate the environmental problems. This study aimed to evaluate the potential of OS and SS as natural calcium resources. The minerals, calcium, magnesium, potassium, phosphorus and sodium were analyzed in OS and SS extracts. Among them, the calcium content was the highest: 36.87 (%) and 33.42 (%) in the OS and SS extracts, respectively. Further, the content of ionized bioavailable form of calcium in OS and SS was higher than that of CaCO3 under simulated gastrointestinal digestion conditions. Additionally, OS and SS were added to kimchi, and their inhibitory effect on kimchi acidification was evaluated by assessing pH, titratable acidity and microbial analysis. As the results indicated that the addition of OS and SS had little effect on inhibiting the growth of lactic acid bacteria. However, it was confirmed that calcium neutralizes the organic acids produced during fermentation. Overall, the results of this study provide preliminary information on the re-use of OS and SS extracts as ionized natural calcium supplements and fermentation retardants.

Effects of salt type on the metabolites and microbial community in kimchi fermentation.

The taste of kimchi is greatly affected by the salt type used during fermentation. Here, we investigated the effects of salts with different mineral contents on the microbial community and metabolite profiles of fermented kimchi using multivariate statistical analysis. We evaluated different types of salt used to prepare kimchi, namely, solar salt aged for 1 year, solar salt aged for 3 years, dehydrated solar salt, and purified salt. The main microorganisms detected in kimchi were Weissella koreensis, Leuconostoc mesenteroides, and Latilactobacillus sakei. Leuconostoc and Weissella were mainly present in kimchi supplemented with solar salt. However, a high proportion of L. sakei was present in kimchi supplemented with purified salt and dehydrated salt. Additionally, using GC-MS-based metabolite analysis, we revealed that the content of free sugars, organic acids, and amino acids differed in kimchi fermented with different salt types. Therefore, we demonstrated that salt type had a pronounced effect on the resultant microbial community and the type and concentration of metabolites present in fermented kimchi.

Antioxidant activity and calcium bioaccessibility of Moringa oleifera leaf hydrolysate, as a potential calcium supplement in food.

Moringa oleifera leaf (ML) is rich in vitamins and minerals, specially abundant calcium, therefore it is widely used as a calcium supplement for food. This study aimed to investigate the antioxidant activity and calcium bioaccessibility of M. oleifera leaf hydrolysate (MLH) as a calcium supplement for kimchi. MLH was prepared under three different proteases, two different protease contents, and three different incubation times. Total phenol content (TPC), total flavonoid content (TFC), and antioxidant activities were investigated. Cellular activity and calcium bioaccessibility were also investigated. The highest calcium level of MLH was observed in 3% Protamex treatment for 4 h. TPC, TFC, and antioxidant activities of MLH in Protamex and Alcalase treatments were higher than those in Flavourzyme treatment (p < 0.05). Moreover, high cell viability and alkaline phosphatase activity were also observed in C2C12 cells. Kimchi containing MLH showed high calcium accessibility compared to kimchi alone. Taken together, the application of MLH could have potential as a calcium supplement for kimchi production.

Kimchi extracts as inhibitors of colour deterioration and lipid oxidation in raw ground pork meat during refrigerated storage.

BACKGROUND: Kimchi is a Korean, traditional fermented food made from Korean cabbage, radish, fermented jeotgal, ginger, garlic, and red pepper powder. It is a good source of natural antioxidants such as phenolic compounds, flavonoids, vitamins, and carotenoids. In this study, the antioxidant effects of various kimchi extracts on raw ground pork during refrigerated storage were investigated. Raw ground pork samples were treated with ascorbic acid, butylated hydroxyl toluene, baechu kimchi extract (BKE), gat kimchi extract (GKE), puchu kimchi extract (PKE), and white kimchi extract (WKE) and compared with raw ground pork without antioxidant treatment (NC). RESULTS: Increased metmyoglobin (MetMb), thiobarbituric acid reacting substance (TBARS), and total bacterial counts (TBC) were observed in all meat samples after storage, whereas pH, lightness, and redness values tended to decrease with increased storage time. All treated samples had lower TBARS and MetMb values and TBC compared to the control samples. Various kimchi ethanol extracts protected raw ground pork from lipid oxidation. The most potent antioxidant was GKE, whereas WKE was the weakest. CONCLUSIONS: This study suggests that the tested extracts, especially kimchi, have potential as natural preservatives to reduce colour degradation, lipid oxidation, and bacterial count in raw ground pork meat. © 2018 Society of Chemical Industry.

Antioxidant action of ganghwayakssuk (Artemisia princeps Pamp.) in combination with ascorbic acid to increase the shelf life in raw and deep fried chicken nuggets.

Raw and deep fried chicken nuggets containing various levels of ganghwayakssuk ethanolic extract (GE) in combination with ascorbic acid (Aa) were evaluated for shelf-life during refrigerated storage (4°C). The pH and color (lightness, redness, and yellowness) values of raw and deep fried samples were significantly affected by the addition of GE (P<0.05). All antioxidant combinations except for Aa+GE 0.01 were effective at delaying lipid oxidation (CD, POV, and TBARS) when compared to the control or Aa. Raw samples with GE 0.2 and Aa+GE 0.1 exhibited lower bacterial populations during storage. The sensory characteristics (color, juiciness, flavor, tenderness, and overall acceptability) did not differ significantly in all deep fried chicken nugget samples, except color, whereas storage time had a significant effect (P<0.05). The results suggest the possibility of utilizing raw and deep fried chicken nuggets with a mixture of ganghwayakssuk and ascorbic acid for the increase of shelf-life and quality.

Effects of kimchi ethanolic extracts on oxidative stability of refrigerated cooked pork.

The antioxidant effect of different kimchi extracts in cooked ground pork during storage for 14 days at 4°C was studied. Cooked ground pork was treated with ascorbic acid, BHT, baechu kimchi (BK), got kimchi (GK), puchu kimchi (PK), and white kimchi (WK) and compared to cooked ground pork without antioxidant. Radical scavenging and chelating activities of kimchi extracts were in the order: GK>PK>BK>WK. Total phenolic contents and flavonoid contents ranged from 32.52 to 46.73 mg of GAE/g and 5.87 to 25.58 mg quercetin/g, respectively. Significantly (P<0.05) lower values of TBARS, peroxide values, and hexanal contents were obtained for GK treated samples compared with cooked pork without antioxidant during refrigerated storage. GK showed good antioxidant activity and was significantly different (P<0.05) from the other treatments. Based on these findings, the natural antioxidants examined may have applications in the development of nutritionally enhanced meat products with enhanced shelf life.

Oxidative and color stability of cooked ground pork containing lotus leaf (Nelumbo nucifera) and barley leaf (Hordeum vulgare) powder during refrigerated storage.

This study aimed to evaluate the oxidative and color stability of cooked ground pork containing lotus leaf powder at 0.1 (LP1) and 0.5% (LP2) as well as barley leaf powder at 0.1 (BP1) and 0.5% (BP2) during refrigerated storage for 10 days. The oxidative stability of these powders was compared with butylhydroxytoluene (BHT). LP1 had higher a* and lower b* values than the control (-) over 4 days (p<0.05). The pH values of the ground pork samples made with addition of LP and BHT decreased until day 4 and then increased. Thiobarbituric acid-reactive substance (TBARS) values were lowest in LP2 on day 10 (p<0.05). The ground pork samples containing LP and BP had lower peroxide values (POVs) and conjugated dienes (CD) compared to the control (-).These results indicate that LP or BP can be incorporated into ground pork to effectively retard oxidation after cooking.

Optimization of replacing pork back fat with grape seed oil and rice bran fiber for reduced-fat meat emulsion systems.

The effects of reducing pork fat levels from 30% to 20% and partially substituting the pork fat with a mix of grape seed oil (0%, 5%, 10% and 15%) and 2% rice bran fiber were investigated based on chemical composition, cooking characteristics, physicochemical and textural properties, and viscosity of reduced-fat meat batters. For reduced-fat meat batters containing grape seed oil and rice bran fiber the moisture and ash contents, uncooked and cooked pH values, yellowness, cohesiveness, gumminess, chewiness, and sarcoplasmic protein solubility were higher than in the control samples. The reduced-fat samples with increasing grape seed oil concentrations had lower cooking loss, emulsion stability, and apparent viscosity. The incorporation of grape seed oil and rice bran fiber successfully reduced the animal fat content in the final products while improving other characteristics.

The antioxidative properties of mustard leaf (Brassica juncea) kimchi extracts on refrigerated raw ground pork meat against lipid oxidation.

The efficacy of varying concentration of mustard leaf kimchi ethanolic extracts (MK) in retarding oxidative rancidity was tested with raw ground pork. Freshly ground pork meat was assigned to one of the following five treatments: control (no antioxidants); AC-0.02 (0.02% ascorbic acid); MK-0.05, 0.1, and 0.2 (0.05%, 0.1% and 0.2% MK, respectively). The pH of the samples decreased and the TBARS values and free fatty acids (%) increased considerably (P<0.05) during storage. The total bacterial count was lower in MK-0.1 and MK-0.2 than the control during storage. The internal L* value and a* value decreased (P<0.05) with the addition of MK. The internal b* value of MK treatments were higher (P<0.05) than that for the control and increased incrementally with MK concentration. The TBARS values and free fatty acids (%) of MK-0.02 was lowest among the treatments. The peroxide value of the control increased until 7 days and reached the maximum value at a certain storage time and decreased thereafter. In the other treatments it increased. All treatments had lower concentration of conjugated dienes (P<0.05) compared to the control sample, after the first day. Mustard leaf kimchi ethanolic extracts exhibited a protective effect against lipid oxidation in raw ground pork.

Effects of replacing pork back fat with vegetable oils and rice bran fiber on the quality of reduced-fat frankfurters.

The effects of substituting olive, grape seed, corn, canola, or soybean oil and rice bran fiber on the chemical composition, cooking characteristics, fatty acid composition, and sensory properties of low-fat frankfurters were investigated. Ten percent of the total fat content of frankfurters with a total fat content of 30% (control) was partially replaced by one of the vegetable oils to reduce the pork fat content by 10%. The moisture and ash content of low-fat frankfurters with vegetable oil and rice bran fiber were all higher than the control (P<0.05). Low-fat frankfurters had reduced-fat content, energy values, cholesterol and trans-fat levels, and increased pH, cooking yield and TBA values compared to the controls (P<0.05). Low-fat frankfurters with reduced-fat content plus rice bran fiber had sensory properties similar to control frankfurters containing pork fat.