Optimization of extraction and nanoencapsulation of kimchi cabbage by-products to enhance the simulated in vitro digestion of glucosinolates.

Kimchi cabbage is a well-known glucosinolate (GLS)-containing vegetable, but its by-products are discarded despite the presence of GLS. The aim of this study was the optimization of the extraction and nanoencapsulation of GLS from kimchi cabbage by-products to enhance the intestinal absorption of GLS. The optimal GLS extraction conditions included steaming thrice as pretreatment, utilizing 70% methanol, and ultrasonication at 20% amplitude for 15 min. Under these conditions, 80.11 ± 4.40 mg/100 g of GLS extraction was obtained and the extraction yield was 81.70 ± 4.73%. The optimized kimchi cabbage by-product extract (KCE) was coated with chitosan-lipid nanoparticles (KCE-NPs) and their stability and release under simulated in vitro gastrointestinal conditions were evaluated. KCE-NPs protected the encapsulated GLS under acidic gastric conditions and released 91.63 ± 0.76% of GLS in the simulated intestinal medium. Therefore, the proposed KCE-NPs are a promising delivery system for increasing GLS absorption.

Freshness Analysis of Raw Laver (Pyropia yenzoensis) Conserved under Supercooling Conditions.

Freezing raw laver is unsuitable for the laver industry due to process characteristics and economic problems. Therefore, this study attempted to investigate supercooled storage to extend the storage period without freezing, rather than refrigeration. To compare and analyze the storage ability of supercooling, the experiment was performed under refrigeration (5 °C), constant supercooling (CS, -2 °C), stepwise supercooling (SS, -2 °C), and freezing (-18 °C) conditions for 15 days, and the physicochemical changes according to the treatment and period were investigated. All SS samples, which were designed for stable supercooling, were kept in a supercooled state for 15 days. Two samples among the twelve total subjected to CS were frozen. At 9 days, the drip losses of the CS and SS samples were 6.32% and 6.48%, respectively, which was two times lower than that of refrigeration and three times lower than that of the frozen samples. The VBN of the refrigerated samples was 108.33 mg/100 g at 6 days, which exceeded the decomposition criterion. Simultaneously, the VBN of the other treatments was under the decomposition criterion of 30 mg/100 g. However, the VBN of both supercooling samples at 15 days increased to higher than the decomposition criterion. Regarding appearance, the refrigerated samples showed tissue destruction at 9 days, but tissue destruction of the CS and CC samples was observed at 15 days, and tissue destruction of the frozen samples was not observed until 15 days. Consequently, supercooling did not maintain quality for longer periods than freezing, but it did extend the shelf life more than refrigeration, and effectively preserved the quality for a short period.

Conditions of the Stepwise Cooling Algorithm for Stable Supercooling Preservation and Freshness of Pork Loin.

Supercooling has the advantage of maintaining the freshness of foods without a phase transition. However, it is hard to sustain the supercooled state. Static temperature control, one of the various supercooling technologies, is used for stable supercooling storage. In this experiment, the effect of following external factors in maintaining the supercooled state of foods was investigated. Three main parameters had an effect on the supercooled state of food: (1) properly setting the lower-temperature limit of the supercooling algorithm, (2) slow cooling to the target temperature, and (3) minimizing temperature fluctuation. Accordingly, the following stepwise cooling algorithm for pork loin was designed: a lower-temperature limit of −3.0 °C and a storage period = 36 h followed by a lower-temperature limit of −3.5 °C for 24 h. The samples conserved at −3.0 °C displayed a 100% supercooled state. Physicochemical properties including drip loss, cooking loss, texture, color, total volatile basic nitrogen (TVBN), and total aerobic count (TAC) of pork loin were analyzed. The drip loss values of the supercooled meat samples were lower than those of the superchilled ones. Furthermore, TVBN and TAC of the treated samples were not significantly different from those of the fresh samples (p > 0.05). In conclusion, supercooling storage extended the freshness and quality of pork loin better than refrigerated storage.

Development of Temperature Control Algorithm for Supercooling Storage of Pork Loin and Its Feasibility for Improving Freshness and Extending Shelf Life.

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.

Development of a Stepwise Algorithm for Supercooling Storage of Pork Belly and Chicken Breast and Its Effect on Freshness.

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.

Deep freezing to maintain the freshness of pork loin during long-term storage.

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.

Physicochemical Properties of Pork Neck and Chicken Leg Meat under Various Freezing Temperatures in a Deep Freezer.

This study was conducted to investigate the effects of freezing and storage temperature (-18°C, -50°C, and -60°C) on the physicochemical properties of pork neck and chicken leg meat in home-scale deep freezers. Pork neck was cut into a thickness of 3 cm (9×9×3 cm, 150 g), individually packed in air-containing packages, and stored at different temperature (-18°C, -50°C, and -60°C) for 6 months. Chicken leg meats were prepared (10 cm long, weighing 70 g) and packed in the same manner. Frozen samples were thawed at 2°C. Physicochemical properties such as thawing loss, cooking loss, water-holding capacity, color, volatile basic nitrogen (VBN), and thiobarbituric acid reactive substances (TBARS) were evaluated. The samples frozen by deep freezing (-60°C) was favorable with respect to thawing loss, color, and VBN. Samples frozen at -60°C had lower values of thawing loss and VBN than those frozen at -18°C for all storage periods (p<0.05). Color parameters were more similar to those of fresh meat than to those of samples frozen at -18°C for 6 months. The TBARS of all samples were below 0.3 mg malondialdehyde/kg, thereby indicating oxidative stability of lipids. Consequently, deep freezing at -60°C may be acceptable for maintaining the quality of fresh pork neck and chicken leg meat for 6 months without deterioration.

Effect of Roasting Time and Cryogenic Milling on the Physicochemical Characteristics of Dried Ginseng Powder.

This study aimed to evaluate the effect of reduced particle size of ginseng by roasting and cryogenic milling on increasing its water solubility and physiological activity. The samples were roasted for different times (9-21 min) and generated in different sizes (10-50, and >50 µm). All roasted samples revealed significantly smaller particle sizes than did non-roasted samples, based on Sauter mean diameter (D [3,2], p < 0.05). Furthermore, the particle sizes of roasted samples decreased until roasting up to 15 min. In terms of the water solubility index (WSI), antioxidant activity, total polyphenol content (TPC), and total polysaccharides according to particle size, 10-20 µm-sized samples showed the highest values when compared with >50 µm-sized samples. Based on roasting time, WSI values of all samples roasted for up to 15 min were higher than those of the control (not roasted) (p < 0.05). Antioxidant activity and TPC also increased with increasing roasting time. Total polysaccharide content was the highest upon roasting for 15 min, except for the 10-20 µm sample. Ginsenoside content of roasted samples >20 µm size was higher than that of the control (not roasted) except after 15 min of roasting. Therefore, roasting and cryogenic milling are effective in producing ginseng root powder.

Effects of Deep Freezing Temperature for Long-term Storage on Quality Characteristics and Freshness of Lamb Meat.

This study investigated the effects of deep freezing and storage temperature (-50°C, -60°C, and -80°C) on the quality and freshness of lamb. To compare the qualities of deep frozen and stored lamb, fresh control and normal freezing conditions (-18°C) were adopted. As quality and freshness parameters, drip loss (thawing loss and cooking loss), water-holding capacity (WHC), texture profile analysis (TPA), thiobarbituric acid reactive substances (TBARS), and total volatile basic nitrogen (TVBN) were evaluated during 5 months of storage. Temperature influenced the drip loss and WHC, and deep freezing minimized the moisture loss during frozen storage compared to the normal freezing condition. Lamb frozen and stored at deep freezing temperature showed better tenderness than that stored in normal freezing conditions. In particular, lamb frozen at lower than -60°C exhibited fresh lamb-like tenderness. Regardless of temperature, evidence of lipid oxidation was not found in any frozen lamb after 5 months, while TVBN was dependent on the applied temperature. Therefore, this study demonstrated that deep freezing could potentially be used to maintain freshness of lamb for 5 months. From the quality and economic aspects, the freezing and storage condition of -60°C is estimated as the optimum condition for frozen lamb.

The Change in Quality Characteristics of Hanwoo in Home Meal Replacement Products under Different Cooking and Freezing Methods.

The market size of home meal replacement (HMR) products has been gradually growing worldwide, even in Korea. In Korean HMR products, meat is the most important food ingredient compared with rice and vegetables. Therefore, this study aimed to evaluate changes in physiochemical and sensory aspects of beef under different preparation processes. For preparing four treatments, beef eye of round (ER) added with salt and sugar (treatment 1) and that without salt and sugar (treatment 2) were mixed with rice and frozen at -50°C. Beef ER without salt and sugar was also topped onto the rice and frozen (treatment 3), and that was topped onto the rice and precooled before freezing (treatment 4). Physiochemical analyses included cooking and drip losses, shear force, color, salt soluble protein, and sensory attributes were tested. The results showed significantly higher drip loss and total loss in beef ER samples 1 and 2, which were mixed with rice, compared to beef ER samples 3 and 4, which were not mixed with rice. A significantly higher discoloration was also observed in beef ER samples 1 and 2, compared to that in samples 3 and 4. In the partial least squares regression (PLSR) analysis, beef ER sample 4 (precooled before freezing) was highly related to sensory attributes, such as flavor, overall acceptability, and juiciness, and far from non-preferred shear force. As a result, beef ER in HMR sample 4 was the most preferable to the sensory panel, and it had the most desirable physicochemical analysis outcomes.