Quality of reduced-fat meat emulsion: effect of pre-emulsified duck skin and hydrocolloids.

This study explored the impact of reduced-fat meat emulsion with pre-emulsified duck skin and hydrocolloids on physicochemical properties such as cooking loss, emulsion stability, apparent viscosity, protein solubility, and texture profile analysis. Six different reduced-fat meat emulsions were produced: control (pork back fat), T1 (duck skin, DS), T2 (pre-emulsified with duck skin, PDS), T3 (PDS + 2% carrageenan), T4 (PDS + 2% alginate), T5 (PDS + 2% pectin), and T6 (PDS + 2% guar gum). Moisture content, protein content, yellowness, and apparent viscosity of reduced-fat emulsion with PDS and hydrocolloids were all higher (P < 0.05) than control. Cooking loss and emulsion stability of T4 and T6 were lower (P < 0.05) than the control values. Cooking loss and total fluid separation were greatest (P < 0.05) for T5. Fat content of reduced-fat emulsion with PDS was lower (P < 0.05) than that of the control. Meat emulsion comprising PDS with alginate resulted in superior physicochemical properties compared to the other reduced-fat meat emulsion.

Effects of organic solvent on functional properties of defatted proteins extracted from Protaetia brevitarsis larvae.

This study investigated the effect of aqueous fat separation and defatting using organic solvents (99% methanol, ethanol, and n-hexane) on the characteristics and functionality of proteins extracted from Protaetia brevitarsis. The defatting efficiency, amino acid composition, protein solubility, and technical properties were the highest when proteins were defatted using n-hexane. Proteins defatted using ethanol were similar in foam capacity and emulsifying capacity. Surface hydrophobicity decreased when using organic solvents, and excessive fat content disrupted the functional properties of the extracted proteins. Proteins extracted using the different solvents displayed different pH values. The pH of the aqueous extract was the lowest. CIE L* a* b* color values also differed using the different extraction methods. Although n-hexane might be the most efficient solvent for defatting the proteins extracted from edible insects, ethanol could also be used to obtain similar foam and emulsifying capacities.

Effects of hydrocolloids on the quality characteristics of cold-cut duck meat jelly.

In this study, we examined the effects of various hydrocolloid (alginate, carrageenan, and konjac) treatments on the quality characteristics of cold-cut duck meat jelly. Seven different types of cold-cut duck meat jelly were prepared: control, without hydrocolloids; T1, 0.5% alginate; T2, 0.5% carrageenan; T3, 0.5% konjac; T4, 0.25% alginate + 0.25% carrageenan; T5, 0.25% carrageen + 0.25% konjac; and T6, 0.25% alginate + 0.25% konjac. The pH and moisture content of the cold-cut duck meat jelly with hydrocolloids was higher (p < 0.05) than that of the control. The highest lightness value was recorded for T4 and T6 (p < 0.05), and the hardness was lower (p < 0.05) in the meat jelly with hydrocolloids than in the control, except for T2 and T5. The springiness of the meat jelly was the highest (p < 0.05) in T1 and T4. The onset, peak, and end temperatures were the lowest (p < 0.05) in the control. The highest appearance score of the meat jelly was observed in T6, and its overall acceptability was higher (p < 0.05) than that of the control, indicating that, of all the treatments, 0.25% alginate + 0.25% konjac yielded the most desirable results. Thus, the combined use of duck skin and gelatin with alginate and konjac is potentially applicable for the development of new cold-cut duck meat products.

Functional Properties of Extracted Protein from Edible Insect Larvae and Their Interaction with Transglutaminase.

Global concern about food supply shortage has increased interest on novel food sources. Among them, edible insects have been studied as a potential major food source. This study aimed to improve the functional properties of protein solutions extracted from Protaetia brevitarsis (PB) by use of transglutaminase (TG) as a cross-linking agent. After various incubation times (10, 20, 30, 60, and 90 min) with TG, the protein solutions were assessed with regard to their amino acid composition, protein nutritional quality, pH, color (yellowness), molecular weight distribution, thermal stability, foam ability (capacity and stability), and emulsion ability (capacity and stability). Incubation with TG changed the amino acid composition of the proteins and shifted the molecular weight distribution towards higher values, while improving the rest of the aforementioned properties. Since the incubation time for 90 min decreased the protein functionality, the optimum incubation time for cross-linking PB-derived protein with TG is 60 min. The application of TG to edible insect proteins ultimately increases its functionality and allows for the development of novel insect processing technology.

Extraction of crude gelatin from duck skin: effects of heating methods on gelatin yield.

The disposal of by-products of duck production, including duck skin, is a serious concern as it results in environmental pollution. The objectives of this study were to investigate the optimal pretreatment conditions for swelling duck skin and their extraction methods as a novel source. Gelatin was extracted using water bath, sonication, superheated steam, and microwave extraction methods. The gelatin extraction yield and gelatin powder yield were the highest with the superheated steam extraction method. The melting point and gel strength of gelatin extracted using the superheated steam method were the lowest. The viscosity of gelatin extracted with the superheated steam and microwave extraction methods was higher than that of gelatin extracted with the other methods. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis patterns of gelatin extracted using the superheated steam and microwave extraction methods showed more intense bands than those of gelatin extracted using the other methods. Our results showed that gelatin extracted from duck skin using the superheated steam extraction method had optimal physical properties and therefore can be used in meat products.

Quality characteristics of duck jerky: combined effects of collagen and konjac.

The effects of curing solution prepared using various ratios of a combination of collagen and konjac (100/0, 80/20, 60/40, 40/60, 20/80, and 0/100) on the quality characteristics of duck jerky were investigated. The moisture, processing yield, water activity, tenderness score, and overall acceptability score of duck jerky were the highest when the ratio of added collagen and konjac was 60/40. The rehydration ratio of duck jerky increased due to the addition of collagen and konjac combinations in curing solution, and was higher for the 60/40 and 40/60 combinations than for the others. The shear force of duck jerky was the highest for the untreated jerky, and the lowest for the jerky formulated with the 60/40 combination of collagen and konjac solution. No significant differences were observed in lightness and yellowness between jerky treated with combinations of collagen and konjac. Taken together, our results indicate that addition of a combination of collagen and konjac at a 60/40 ratio results in good quality characteristics of duck jerky. Thus, we suggest that the use of combinations of collagen and konjac in duck jerky processing is beneficial for improving the quality characteristics of the jerky.

Effects of replacing pork fat with grape seed oil and gelatine/alginate for meat emulsions.

The effects of using grape seed oil in combination with gelatine and alginate on the physicochemical characteristics of meat emulsions were examined. Four different meat emulsions were manufactured and half the conventional fat was substituted with pre-emulsified grape seed oil with gelatine and/or alginate: T1, only grape seed oil; T2, grape seed oil and gelatine; T3, grape seed oil and alginate, T4, grape seed oil, gelatine, and alginate. Meat emulsion containing only pork back fat was compared as control. Results revealed that T4 was moister, lighter, more viscous, and stable in emulsion than control and value of ash contents of T4 was higher than those of control. Moreover, the value of fat content, pH, firmness, chewiness, toughness, and lipid oxidation of the T4 meat emulsion were lower than those of control. The meat emulsions with emulsified grape seed oil were more principally elastic than viscous and appearent viscosity was the highest in T4. In conclusion, instead of using each ingredient alone, pre-emulsified grape seed oil, gelatine, and alginate can replace partial pork fat with in meat emulsion formulations results in optimized meat processing properties.

Comparative effects of dry-aging and wet-aging on physicochemical properties and digestibility of Hanwoo beef.

OBJECTIVE: The purpose of this study was to investigate the effects of aging methods (AM) i.e. dry-aging (DA) and wet-aging (WA) on the physicochemical properties and in vitro digestibility of proteins in beef short loin. METHODS: Short loins (M. longissmus lumborum), were trimmed and boned-out on the fifth day postmortem, from a total of 18 Hanwoo, which were purchased from a commercial slaughterhouse. Short loins were separated randomly grouped into one of the three treatments: control, WA (1°C, 7 days), and DA (1°C, 0.5 m/s, 85% relative humidity [RH], 30 days). RESULTS: Dry-aged beef (DAB) exhibited higher pH, water holding capacity (WHC), myofibrillar fragmentation index (MFI), and digestibility, however lower lightness, redness, and yellowness values, cooking loss, and shear force (SF), than those of wet-aged beef (WAB) (p<0.05). The myosin light chain band intensity of DAB was higher than that of control and WAB in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The in vitro digestibility of aged beef was highly (p<0.001) correlated to physicochemical properties except WHC. The correlation coefficient between AMs and WHC was higher than that between AM and SF (p<0.05) or MFI (p<0.001). A high correlation was observed between SF and MFI (p<0.001). CONCLUSION: Thus, we believe that DAB is more advantageous than WAB owing to its high digestibility and WHC and low SF.

Edible Insects as a Protein Source: A Review of Public Perception, Processing Technology, and Research Trends.

This review summarizes the current trends related to insect as food resources among consumers, industry, and academia. In Western societies, edible insects have a greater potential as animal feed than as human food because of cultural biases associated with harmful insects, although the abundant characteristics of edible insects should benefit human health. Nevertheless, many countries in Asia, Oceania, Africa, and Latin America utilize insects as a major protein source. Using insects can potentially solve problems related to the conventional food-supply chain, including global water, land, and energy deficits. Academic, industry, and government-led efforts have attempted to reduce negative perceptions of insects through developing palatable processing methods, as well as providing descriptions of health benefits and explaining the necessity of reducing reliance on other food sources. Our overview reveals that entomophagy is experiencing a steady increase worldwide, despite its unfamiliarity to the consumers influenced by Western eating habits.

Technical Functional Properties of Water- and Salt-soluble Proteins Extracted from Edible Insects.

The amino acid composition, protein quality, and protein functionality of protein solution extracted from three edible insect species were investigated. We used 0.02% ascorbic acid and 0.58 M saline solution to extract water-soluble and salt-soluble proteins from the three insect species. Extracted protein solutions of Tenebrio molitor (TM), Allomyrina dichotoma (AD), and Protaetia brevitarsis seulensis (PB) were divided into six groups, according to species and solubility: WTM, WAD, WPB (water-soluble), and STM, SAD, and SPB (salt-soluble). Defatted TM had the highest protein content, but its protein solubility was the lowest, for both water and saline solutions. Amino acid composition differed by edible insect species and buffer type; SPB had the highest protein quality, followed by WPB. PB had a higher pH than the other species. Color values also differed among species. SPB had abundant high molecular weight proteins, compared with other treatments; and also had the highest foaming capacity, foam stability, and emulsifying capacity. In conclusion, PB is a good source of functional protein compared with the other studied species. Additionally, protein extraction using saline solution is promising as a useful method for improving edible insect protein functionality.

Effects of natural nitrite source from Swiss chard on quality characteristics of cured pork loin.

OBJECTIVE: This study was conducted to evaluate quality characteristics of cured pork loin with natural nitrite source from Swiss chard. METHODS: Pork loin was cured in the brine and the ratio of water and fermented Swiss chard (FSC) solution in the brine was changed by 4:0 (Control), 3:1 (T1), 1:1 (T2), 1:3 (T3), 0:4 (T4) and pickled samples with 0.012% nitrite (PC) and nitrite free brine (NC) were considered as the control. RESULTS: The pH values of cured pork loins with FSC were decreased with increasing addition level of FSC. Cooking loss was not significantly different among all treatments. T4 had the lowest value in moisture content and lightness value and the highest value in curing efficiency. The redness value of T4 was not significantly different from that of PC in raw. After cooking, however, it was higher than that of PC. The yellowness value of cured pork loin added with FSC was increased with increasing level of FSC. Volatile basic nitrogen content of cured pork loin added with FSC was higher than PC and NC. Thiobarbituric acid reactive substance value of cured pork loin added with FSC was decreased with increasing FSC level. Residual nitrite level and shear force were increased with increasing FSC level. In the sensory evaluation, sensory score for flavor, off-flavor, hardness, chewiness, juiciness, and overall acceptability were not significantly different among all treatments. However, sensory score for color was increased when the concentration of FSC added to pork loin was increased. CONCLUSION: Fermented Swiss chard solution had a positive effect on redness, lipid oxidation. Although there were shown in protein decomposition and sensory, Swiss chard can be replaced sodium nitrite as natural curing agent.

Quality characteristics of pork loin cured with green nitrite source and some organic acids.

This study was conducted to improve the quality characteristics of cured meat with natural nitrite. Control and treatment were conducted as follows: nitrite free, marinated with sodium nitrite and ascorbic acid, marinated with only fermented spinach (FS), and marinated with FS adding ascorbic acid, malic acid, citric acid, and tartaric acid. Treatments were pickled with regulated brine (8% salt and 0.08% nitrite). Cured meat with FS adding ascorbic acid, malic acid, and citric acid had higher redness values than sodium nitrite with ascorbic acid on cooked meat. There was a positive effect on lipid oxidation except for citric acid. Protein degradation appeared more in malic acid and tartaric acid treatment than others. Residual nitrite level was lower when adding organic acids. Among various organic acid, ascorbic acid had the highest efficient on quality properties of cured meat. Thus, ascorbic acid was a proper ingredient when curing meat product.

Quality Characteristics of Samgyetang according to the Sodium Chloride Level and with/without Phosphate in Broth.

In this study, the effect of sodium chloride (salt) concentration and phosphate on the quality properties of samgyetang was investigated. Increasing the salt concentration by 0.5% increased the moisture and ash content, salinity, water holding capacity (WHC), and thiobarbituric acid reactive substances (TBARS), whereas the protein content, pH, cooking losses, and shear forces were decreased. Addition of phosphate to the brine increased the pH and WHC, but decreased the TBARS, cooking losses, and shear forces. In a sensory evaluation, the scores for flavor and overall acceptability were the highest when the salt concentration of the brine was 2.0%. Overall, this study shows that the salt concentration and addition of phosphate to the brine of samgyetang substantially influences the overall quality of the chicken breast. Based on quality measurements and sensory scores, a 2.0% salt concentration with the addition of phosphate appear to be the most suitable conditions for the manufacturing of marinated samgyetang.

Combination effects of nitrite from fermented spinach and sodium nitrite on quality characteristics of cured pork loin.

Objective: The purpose of this study was to investigate the effect of fermented spinach derived nitrite and sodium nitrite on cured pork loin. Methods: The following treatments were prepared using brine (8% (w/v) salt): Control (-), no nitrite added; Control (+), 0.08% (w/v) sodium nitrite brine; T1, 0.04% (w/v) nitrite fermented spinach juice in 0.04% (w/v) sodium nitrite brine; T2, spinach juice in 0.04% (w/v) sodium nitrite brine; T3, 0.04% (w/v) nitrite fermented spinach juice used as sodium nitrite free brine; and T4, spinach juice used as sodium nitrite free brine. T2 and T4 were incubated to allow to reduce nitrate to nitrite. Results: Spinach juice did not affect cooking loss and pH but negatively influenced flavor and overall acceptability (p<0.05). T1 samples containing synthetic and natural nitrites showed the highest redness values. Spinach juice negatively affected volatile basic nitrogen (VBN); however, thiobarbituric acid reactive substance (TBARS) values of T1 and T3 were similar to those of controls (+) (p>0.05). Residual nitrite content decreased with decreasing synthetic nitrite levels. T1 and control samples showed no significant differences in overall acceptability (p>0.05). Conclusion: Thus, combined synthetic and natural nitrites improved the quality of cured pork loin.

Effects of Pre-cooking Methods on Quality Characteristics of Reheated Marinated Pork Loin.

We evaluated the effects of pre-cooking methods on the quality of reheated marinated pork loin. Frozen marinated pork loins cooked using various methods (boiling, grilling, pan frying, infrared cooking, and superheated steam cooking) were reheated in a microwave, and their pH, color, cooking loss, re-heating loss, total loss, thiobarbituric acid reactive substance (TBARS) value, sensory properties, and shear force were determined. Although all parameters varied with different cooking methods, lightness values and TBARS values showed the tendency to decrease and increase, respectively, after reheating. Superheated steam-cooked samples showed the lowest values of cooking loss, total loss, TBARS value, and shear force (p<0.05) and the highest lightness, redness, and yellowssness values and juiciness, chewiness, and overall acceptability scores (p<0.05). These results show that pre-cooking with superheated steam maintains the quality characteristics of marinated pork loin upon reheating. Therefore, pre-cooking with superheated steam may be beneficial for the commercial distribution of frozen cooked marinated pork loin.

The Dry-aging and Heating Effects on Protein Characteristics of Beef Longissiumus Dorsi.

The aim of this study was to investigate the effects of dry-aging (DA) and the cooking process on the myofibril protein functionalities and in vitro digestibility of proteins in beef loin. Six sirloins from beef were dry-aged for 28 d, and the control group (n=6) was analyzed 2 d postmortem for this study. Dimensional changes (reduction of thickness and surface shrinkage) after cooking were significantly greater in the control group than the DA group, whereas the shear force of the DA group was significantly lower than that of the control. Effect of cooking on aggregation, hydrophobicity, and in vitro digestibility were significantly higher in the DA group than in the control. After cooking, the protein in DA sirloins was more oxidized than in the control samples. According to the sodium dodecyl sulfate-polyacrylamide gel electrophoresis result, the low molecular weight bands (below 17 kDa) increased in the DA group, finding that the protein characteristics of dry-aged beef was affected by cooking.

Effect of hydrocolloids on the quality of restructured hams with duck skin.

We investigated the quality of duck ham restructured with various hydrocolloids (Alginic acid, Konjac, Carrageenan) on proximate composition, cooking loss, emulsion stability, pH, color, texture profile analysis (TPA), protein solubility, sensory characteristics, and apparent viscosity. Restructured duck ham was prepared as follows: control with no hydrocolloids, T1 (Alginate 1%), T2 (Alginate 0.5% + Konjac 0.5%), T3 (Alginate 0.7% + Konjac 0.3%), T4 (Alginate 0.5% + Carrageenan 0.5%), and T5 (Alginate 0.7% + Carrageenan 0.3%). The restructured duck hams with hydrocolloids had higher value for moisture content, ash content, and apparent viscosity than the control (P < 0.05). The cooking loss, total expressible fluid and fat separation, redness, hardness, cohesiveness, gumminess, and chewiness of restructured duck hams with hydrocolloids was lower than those of the control (P < 0.05). The sensory score for overall acceptability of restructured duck ham with T1 (1% alginate) and T2 (0.5% alginate + 0.5% konjac) was higher than that of the control (P < 0.05). Thus, this study showed that adding 1% alginate or 0.5% alginate + 0.5% konjac in restructured duck ham formulations results in optimized quality characteristics.

A study of the quality characteristics of frozen Korean rice cake by using different thawing methods.

The characteristics of frozen rice cakes after thawing them using different methods, such as standing at room temperature (NT), running water (RWT), pan-grill (PT), steam (ST), microwave (MWT), and superheated steam thawing (SHST), were compared. Frozen rice cakes treated by MWT or SHST showed the shortest thawing time of 3 min. The MWT treatment showed the largest thawing loss, while the ST treatment showed the highest moisture content. The ST, RWT, and MWT treatments showed the highest water activity values. The NT treatment exhibited the highest hardness values, whereas the ST treatment showed the lowest values, possibly due to the adverse effects of high temperature on them. Sensory evaluation showed differences in appearance, moistness, and tenderness according to the thawing method, but there was no significant difference in overall acceptability. This study suggests that the qualities of frozen rice cakes varied depending on the different thawing methods.

Effects of Replacing Pork with Tuna Levels on the Quality Characteristics of Frankfurters.

The aim of this study was to evaluate the effects of pork and tuna levels on the quality characteristics of frankfurters and to establish a suitable percentage of added tuna. The levels of pork meat (PM) and yellow-fin tuna (YFT) in the test frankfurters were as follows: 100% PM (control), 90% PM+10% YFT (T1), 80% PM+20% YFT (T2), 70% PM+30% YFT (T3), 60% PM+40% YFT (T4), and 50% PM+50% YFT (T5). The pH of the frankfurter batters significantly decreased with increasing tuna levels, because the pH of the tuna is lower than that of the pork. The water holding capacity did not differ significantly in frankfurters containing up to 30% tuna, whereas that of the 40% tuna-containing frankfurter was significantly lower than the control. Cooking loss did not differ significantly. At up to 10% tuna, apparent viscosity did not differ significantly, whereas at 20% tuna, it was significantly lower than the control. Fat separation and total expressible fluid separation at up to 30% tuna did not differ from the control; however, when more than 30% was added, higher losses were observed. The hardness of frankfurters containing more than 40% tuna was lower than that of the control, but there was no significant difference in springiness. The overall acceptability of frankfurters manufactured with up to 30% tuna did not differ significantly from the control. These results suggest that the addition of 30% tuna does not affect the quality of frankfurters made from pork.

Distribution of Microorganisms in Cheongyang Red Pepper Sausage and Effect of Central Temperature on Quality Characteristics of Sausage.

The objective of this study was to provide preliminary data for food industry by investigating the distribution of microorganisms in raw materials and sausage examining the effect of heating temperature on sausage quality. Total microbes in sausage ranged 2.21-3.11 Log CFU/g. Bacillus pumilus, B. licheniformis, Staphylococcus saprophyticus, and Enterococcus faecalis were detected on sausage. Total microbes in raw materials was 1.59-7.16 Log CFU/g. Different types of microorganisms were found depending on raw materials, with B. pumilus and B. subtilis were being detected in both raw materials and sausage. Total microbes in sausage after heating was in the range of 1.10-2.22 Log CFU/g, showing the trend of decrease in total microbe with increasing heating temperature, although the decrease was not significant. With increasing heating temperature, pH and hardness were also increased. The yield of sausage manufactured at 85°C was 95.42% while that manufactured at 65°C was 96.67%. Therefore, decreasing heating temperature during sausage production might increase yield and save energy without microbiological effect.