Geun-Pyo Hong

Effect of Frozen Storage Temperature on the Quality of Premium Ice Cream

The market sales of premium ice cream have paralleled the growth in consumer desire for rich flavor and taste. Storage temperature is a major consideration in preserving the quality attributes of premium ice cream products for both the manufacturer and retailers during prolonged storage. We investigated the effect of storage temperature (−18℃, −30℃, −50℃, and −70℃) and storage times, up to 52 wk, on the quality attributes of premium ice cream. Quality attributes tested included ice crystal size, air cell size, melting resistance, and color. Ice crystal size increased from 40.3 μm to 100.1 μm after 52 wk of storage at −18℃. When ice cream samples were stored at −50℃ or −70℃, ice crystal size slightly increased from 40.3 μm to 57-58 μm. Initial air cell size increased from 37.1 μm to 87.7 μm after storage at −18℃ for 52 wk. However, for storage temperatures of −50℃ and −70℃, air cell size increased only slightly from 37.1 μm to 46-47 μm. Low storage temperature (−50℃ and −70℃) resulted in better melt resistance and minimized color changes in comparison to high temperature storage (−18℃ and −30℃). In our study, quality changes in premium ice cream were gradually minimized according to decrease in storage temperature up to−50℃. No significant beneficial effect of −70℃ storage was found in quality attributes. In the scope of our experiment, we recommend a storage temperature of −50℃ to preserve the quality attributes of premium ice cream.

Effect of NaCl, Gum Arabic and Microbial Transglutaminase on the Gel and Emulsion Characteristics of Porcine Myofibrillar Proteins.

This study investigated the effect of gum arabic (GA) combined with microbial transglutaminase (TG) on the functional properties of porcine myofibrillar protein (MP). As an indicator of functional property, heat-set gel and emulsion characteristics of MP treated with GA and/or TG were explored under varying NaCl concentrations (0.1-0.6 M). The GA improved thermal gelling ability of MP during thermal processing and after cooling, and concomitantly added TG assisted the formation of viscoelastic MP gel formation. Meanwhile, the addition of GA decreased cooking yield of MP gel at 0.6 M NaCl concentration, and the yield was further decreased by TG addition, mainly attributed by enhancement of protein-protein interactions. Emulsion characteristics indicated that GA had emulsifying ability and the addition of GA increased the emulsification activity index (EAI) of MP-stabilized emulsion. However, GA showed a negative effect on emulsion stability, particularly great drop in the emulsion stability index (ESI) was found in GA treatment at 0.6 M NaCl. Consequently, the results indicated that GA had a potential advantage to form a viscoelastic MP gel. For the practical aspect, the application of GA in meat processing had to be limited to the purposes of texture enhancer such as restructured products, but not low-salt products and emulsion-type meat products.

Influence of High Hydrostatic Pressure on the Capsicum Oleoresin Encapsulated by Globular Protein

We studied herein the effects of high hydrostatic pressure on the physical properties of capsicum oleoresin encapsulated with globular protein, such as whey protein isolates (WPI), soybean protein isolates (SPI), and casein protein (CSP). After pressurization at 0.1, 100, 200, and 300 MPa with various concentrations (0.1, 1, 2, and 5 wt%) of proteins, the particle size, ζ-potential, and interface tension were evaluated. Furthermore, the encapsulation efficiency (EE), release study, and morphology were investigated to study the effects of high hydrostatic pressurization upon emulsion stability. While the pressurized emulsion droplet size of capsicum oleoresin emulsion with the protein decreased, the 0.1 wt% concentration of SPI presented the smallest size at 257.37 nm. The interface tension of all protein emulsions decreased slightly after high-pressure treatment according to the increment of the pressure level. EE (%) of the WPI, SPI, and CSP emulsions increased when the pressure level increased. The lowest EE 48.91% was presented in pressurized WPI emulsion at 0.1 MPa while CSP emulsion at 300 MPa showed the highest EE about 65.76%. Over twelve hours, the core material of the pressurized protein emulsions was released slowly compared to non-pressurized conditions with the WPI and CSP emulsions. At the end of the storage of the WPI and CSP non-pressured emulsions, the remaining amount of encapsulated capsicum oleoresin was only 10% and 40%, respectively, less than emulsions treated under high pressurization. Thus, the high pressurized protein could be a candidate for the encapsulation of the capsicum oleoresin.

Effects of Artificial Supercooling Followed by Slow Freezing on the Microstructure and Qualities of Pork Loin

This study investigated the effects of artificial supercooling followed by still air freezing (SSF) on the qualities of pork loin. The qualities of pork frozen by SSF were compared with the fresh control (CT, stored at 4℃ for 24 h), slow freezing (SAF, still air freezing) and rapid freezing (EIF, ethanol immersion freezing) treatments. Compared with no supercooling phenomena of SAF and EIF, the extent of supercooling obtained by SSF treatment was 1.4℃. Despite that SSF was conducted with the same method with SAF, application of artificial supercooling accelerated the phase transition (traverse from -0.6℃ to -5℃) from 3.07 h (SAF) to 2.23 h (SSF). The observation of a microstructure indicated that the SSF prevented tissue damage caused by ice crystallization and maintained the structural integrity. The estimated quality parameters reflected that SSF exhibited superior meat quality compared with slow freezing (SAF). SSF showed better water-holding capacity (lower thawing loss, cooking loss and expressible moisture) and tenderness than SAF, and these quality parameters of SSF were not significantly different with ultra-fast freezing treatment (EIF). Consequently, the results demonstrated that the generation of supercooling followed by conventional freezing potentially had the advantage of minimizing the quality deterioration caused by the slow freezing of meat.

Change of Multiple-Layered Phospholipid Vesicles Produced by Electrostatic Deposition of Polymers during Storage

Abstract In this study, 1 wt% lecithin (–), chitosan (+), and λ-carrageenan (–) were prepared to manufacture multiple-layered liposomes with optimal formulations developed in a previous study by using layer-by-layer electrostatic deposition. We observed their particle size, ζ-potential, sedimentation behavior, and microstructure for 6 weeks. Multiple-layered liposomes were quenched with calcein to evaluate stability in terms of factors such as encapsulation efficiency and released amount of calcein. The particle size of multi-layered liposomes increased with storage periods and the ζ-potential of multiple-layered liposomes gained a neutral charge. Interestingly, negatively charged layered liposomes were smaller than positively charged layered liposomes and showed a lower polydispersity index. Moreover, the ζ-potential did not apparently change compared to positively charged layered liposomes. For the calcein release study, multiple-layered liposomes significantly sustained quenched calcein more than that observed using non-layered liposomes. This study showed that it was possible to increase the thickness of the liposome surface and to manipulate its charge using chitosan and λ-carrageenan through electrostatic deposition. Results showed that manufacturing negatively charged multiple-layer (over 4-layer) liposomes with charged biopolymer improved the physicochemical stability of liposomes.

Comparison of Moisture Sorption Isotherms and Quality Characteristics of Freeze-Dried and Boiled-Dried Abalone

Abstract This study investigated the moisture sorption isotherm (MSI) profiles of freeze-dried (FD) and boiled-dried (BD) abalone at 15°C, 25°C, and 35°C, and compared the quality characteristics of the abalone after rehydration. The equilibrium moisture content (EMC) and the calculated monolayer moisture content of FD abalone were higher than those of BD abalone. After rehydration, FD abalone showed a higher yield and a lower shear force than BD abalone. Additionally, the appearance of FD abalone was similar to that of fresh abalone, reflecting a potential application of FD to produce value-added dried abalone.

Studies on the Anti-Oxidative Function of trans-Cinnamaldehyde-Included β-Cyclodextrin Complex

trans-Cinnamaldehyde (tCIN), an active compound found in cinnamon, is well known for its antioxidant, anticancer, and anti-inflammatory activities. The β-cyclodextrin (β-CD) oligomer has been used for a variety of applications in nanotechnology, including pharmaceutical and cosmetic applications. Here, we aimed to evaluate the anti-inflammatory and antioxidant effects of tCIN self-included in β-CD complexes (CIs) in lipopolysaccharide (LPS)-treated murine RAW 264.7 macrophages. RAW 264.7 macrophages were treated with increasing concentrations of β-CD, tCIN, or CIs for different times. β-CD alone did not affect the production of nitric oxide (NO) or reactive oxygen species (ROS). However, both tCIN and CI significantly reduced NO and ROS production. Thus, CIs may have strong anti-inflammatory and antioxidant effects, similar to those of tCIN when used alone.

Influence of autoclave treatment and enzymatic hydrolysis on the antioxidant activity of Opuntia ficus-indica fruit extract

The objectives of this study were to obtain Opuntia ficus-indica fruit (OFIF) extract by autoclave treatment, to convert the flavonoid glycosides in the autoclave extract (AE) to aglycones by enzymatic hydrolysis, and to compare the antioxidant activity of AE and OFIF extracts obtained by other conventional methods. It was revealed that the total polyphenol and flavonoid content and antioxidant activity of AE were higher than those of water extract but were a slightly lower than those of ethanol extract, which indicates that autoclave treatment might be an efficient extraction method for OFIF. Moreover, it was confirmed that the conversion of various flavonoid glycosides to aglycones in all the OFIF extracts does not significantly affect the antioxidant activities. Therefore, it is extrapolated that the antioxidant activity might be correlated to the intestinal absorption rates and metabolic pathway induction upon oral administration rather than the structure of compound itself.

Effect of Soy Protein Hydrolysates Prepared by Subcritical Water Processing on the Physicochemical Properties of Pork Patty during Chilled Storage

The present study was carried out to investigate the effects of soy protein hydrolysates (SPHs) addition on the quality characteristics of pork patties. The SPHs was prepared by subcritical water process (SWP) at 180℃ without holding time and mixed with the pork patty components at varying concentrations (0-3%), and the patties were stored at 4℃ for 14 d. As quality parameters, instrumental color, thiobarbituric acid-reactive substances (TBARS), pH, water holding capacity (WHC) and shear force were measured at the end of storage. Regardless of SPHs concentration, the addition of SPHs significantly manifested low L* and high a* values compared to those of untreated control (p<0.05). For b* value, addition of SPHs in the 0.5-1.5% was unaffected, while >2.0% of SPHs caused significantly lower b* than control (p<0.05). The color changes in pork patties with and without SPHs were also identified in visual appearance where the pork patties containing 0.5-2.0% showed bright red color which was comparable to brownish color of control and patties containing >2.5% SPHs. Lipid oxidation was delayed by the addition of 0.5-1.5% SPHs, while it was accelerated by the addition of 3% SPHs. The pH of patties increased with increasing concentration of SPHs, whereas there were no significant differences in WHC and shear force of patties. Consequently, the results indicated that the addition of 0.5-1.5% SPHs had a potential advantage in suppressing oxidative deterioration of fat-containing meat products during chilled storage.

Effect of High Pressure on the Porcine Placenral Hydrolyzing Activity of Pepsin, Trypsin and Chymotrypsin

This study investigated the effects of protease treatments (trypsin, chymotrypsin, and pepsin) under various pressure levels (0.1-300 MPa) for the characteristics of porcine placenta hydrolysates. According to gel electrophoretic patterns, the trypsin showed the best placental hydrolyzing activity followed by chymotrypsin, regardless of the pressure levels. In particular, the peptide bands of tryptic-digested hydrolysate were not shown regardless of applied pressure levels. The peptide bands of hydrolysate treated chymotrypsin showed gradual decreases in molecular weights (Mw) with increasing pressure levels. However, the pepsin did not show any evidences of placental hydrolysis even though the pressure levels were increased to 300 MPa. The gel permeation chromatography (GPC) profiles showed that the trypsin and pepsin had better placental hydrolyzing activities under high pressure (particularly at 200 MPa), with lower Mw distributions of the hydrolysates. Pepsin also tend to lower the Mw of peptides, while the major bands of hydrolysates being treated at 300 MPa were observed at more than 7,000 Da. There were some differences in amino acid compositions of the hydrolysates, nevertheless, the peptides were mainly composed of glycine (Gly), alanine (Ala), hydroxyproline (Hyp) and proline (Pro). Consequently, the results indicate that high pressure could enhance the placental hydrolyzing activities of the selected proteases and the optimum pressure levels at which the maximum protease activity is around 200 MPa.