Changes in the Physical Properties of Calcium Alginate Gel Beads Under a Wide Range of Gelation Temperature Conditions.

Until now, most studies using calcium alginate gel (CAG) have been conducted primarily at room temperature (20 °C) without considering gelation temperature. Moreover, the effects of gelation temperature on the physical properties of CAG beads have not been studied in detail. We aimed to study the effect of gelation temperature on the physical properties (diameter, sphericity, and rupture strength) of CAG beads. Response surface methodology was used in this study. The independent variables were sodium alginate concentration (X1, 1.2%-3.6%, w/v), calcium lactate concentration (X2, 0.5%-4.5%, w/v), gelation temperature (X3, 5-85 °C), and gelation time (X4, 6-30 min). Diameter (Y1, mm), sphericity (Y2, %), and rupture strength (Y3, kPa) were selected as the dependent variables. A decrease in gelation temperature increased the diameter, sphericity and rupture strength of the CAG beads. Additionally, the CAG beads prepared at 5 °C exhibited the highest rupture strength (3976 kPa), lowest calcium content (1.670 mg/g wet), and a regular internal structure. These results indicate that decreasing the gelation temperature slows the calcium diffusion rate in CAG beads, yielding a more regular internal structure and increasing the rupture strength of the beads.

Effects of Thermal Treatment on the Physical Properties of Edible Calcium Alginate Gel Beads: Response Surface Methodological Approach.

Calcium alginate gel (CAG) has been widely investigated for the development of artificial foods; however, there are few studies on its thermal stability. This study aimed to monitor changes in the physical properties of CAG beads during heat treatment using response surface methodology. Heating temperature (X1, 40-100 °C) and heating time (X2, 5-60 min) were chosen as independent variables. The dependent variables were rupture strength (Y1, kPa), size (Y2, µm), and sphericity (Y3, %). The heating temperature (X1) was the independent variable that had a significant effect on the rupture strength (Y1) and size (Y2). Rupture strength (Y1) increased as the heating temperature (X1) increased; at the same time, the CAG beads size (Y2) decreased. With all conditions, the values of sphericity (Y3) were over 94%. SEM images revealed that increase in the rupture strength of the CAG beads by heat treatment resulted from their porous structures. Loss of moisture by syneresis, occurring with heat treatment, was judged to create a dense porous structure of CAG beads. Our findings offer useful information for cooking or sterilizing food products utilizing CAG beads. In addition, thermal treatment could be applied to produce hard CAG beads with a high rupture strength.

A Standardized Phlorotannin Supplement Attenuates Caffeine-Induced Sleep Disruption in Mice.

In our previous studies, a standardized phlorotannin (brown seaweed polyphenol) supplement (PS) exhibited sleep-promoting effects via type A γ-aminobutyric acid-benzodiazepine receptors in mice. In addition, in human clinical trials, it decreased wake after sleep onset in adults with sleep disturbance. In this follow-up study, we investigated whether PS attenuates caffeine-induced sleep disruption in mice. The effects of PS were evaluated in a caffeine model by analyzing sleep architecture based on electroencephalogram and electromyogram findings, and were compared with the effects of a well-known sedative-hypnotic drug zolpidem (ZPD). As expected, oral administration of caffeine (25 mg/kg) significantly increased sleep latency and decreased the amount of non-rapid eye movement sleep (NREMS). In the caffeine + PS and caffeine + ZPD groups, PS (500 mg/kg) attenuated caffeine-induced sleep disruption, and its effects were comparable with those of ZPD (10 mg/kg). In particular, PS inhibited the arousal effects of caffeine without change in delta activity during NREMS, whereas ZPD produced a decrease in the delta activity. Considering global trends in coffee and energy drink consumption, our finding suggest that PS may be useful to relieve transitory insomnia symptoms caused by caffeine consumption, unlike the prescription drug ZPD.

In vitro antibacterial activity and synergistic antibiotic effects of phlorotannins isolated from Eisenia bicyclis against methicillin-resistant Staphylococcus aureus.

Six phlorotannins, isolated from Eisenia bicyclis, were evaluated for antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). The minimum inhibitory concentrations (MIC) of the compounds were in the range 32 to 64 µg/mL. Phlorofucofuroeckol-A (PFF) exhibited the highest anti-MRSA activity, with an MIC of 32 µg/mL. An investigation of the interaction between these compounds and the ß-lactam antibiotics ampicillin, penicillin, and oxacillin revealed synergistic action against MRSA in combination with compound PFF. To our knowledge, this is the first report on the anti-MRSA activity of phlorotannins from E. bicyclis. The results obtained in this study suggest that the compounds derived from E. bicyclis can be a good source of natural antibacterial agents against MRSA.

13-Week oral toxicity study of oil derived from squid (Todarodes pacificus) in Sprague-Dawley rats.

Recommendations to increase the consumption of the long-chain omega-3 fatty acids are challenged by the global problem of declining fish stocks. Non-traditional and more sustainable sources of the long-chain omega-3 fatty acids are needed. Squid (Todarodes pacificus) represents a uniquely sustainable source of these fatty acids. A 13-week oral toxicity study was conducted in male and female Sprague-Dawley rats administered either 0, 250, 500, or 1000µl/kg body weight (bw)/day of a refined squid oil. All of the rats survived through to the end of the study. All of the rats grew normally and had normal clinical and ophthalmic observations. No signs of toxicity were evident from clinical chemistry, hematology, and urinalysis data measured. No abnormal findings attributable to exposure to purified squid oil were observed following the necropsy of male and female rats and the histopathological examination of the organs. The no-observed-adverse-effect level for refined squid oil was determined to be 1000µl/kg bw/day, the highest dose tested.

Depressive effects on the central nervous system and underlying mechanism of the enzymatic extract and its phlorotannin-rich fraction from Ecklonia cava edible brown seaweed.

Marine plants have been reported to possess various pharmacological properties; however, there have been few reports on their neuropharmacological effects. Terrestrial plants have depressive effects on the central nervous system (CNS) because of their polyphenols which make them effective as anticonvulsants and sleep inducers. We investigated in this study the depressive effects of the polyphenol-rich brown seaweed, Ecklonia cava (EC), on CNS. An EC enzymatic extract (ECEE) showed significant anticonvulsive (>500 mg/kg) and sleep-inducing (>500 mg/kg) effects on the respective mice seizure induced by picrotoxin and on the mice sleep induced by pentobarbital. The phlorotannin-rich fraction (PTRF) from ECEE significantly potentiated the pentobarbital-induced sleep at >50 mg/kg. PTRF had binding activity to the gamma aminobutyric acid type A (GABA(A))-benzodiazepine (BZD) receptors. The sleep-inducing effects of diazepam (DZP, a well-known GABA(A)-BZD agonist), ECEE, and PTRF were completely blocked by flumazenil, a well-known antagonist of GABA(A)-BZD receptors. These results imply that ECEE produced depressive effects on CNS by positive allosteric modulation of its phlorotannins on GABA(A)-BZD receptors like DZP. Our study proposes EC as a candidate for the effective treatment of neuropsychiatric disorders such as anxiety and insomnia.

Isolation and identification of antitumor promoters from the seeds of Cassia tora.

A methanol extract of Cassia tora seeds was successively partitioned with diethyl ether, chloroform, ethyl acetate, and water, and the antitumor-promoting activity of the solvent fractions was determined by inhibition of Epstein- Barr virus early antigen (EBV-EA) activation induced by teleocidin B-4 in Raji cells. The diethyl ether (68.7%) and chloroform (91.2%) fractions and the hydrolysate (94.3%) of the ethyl acetate fraction had strong inhibitory activities. The chloroform and ethyl acetate fractions were chromatographed on silica gel and further purified by HPLC. Three active compounds, obtusifolin-2-glucoside (75.0%), chryso-obtusin-6-glucoside (56.8%), and norrubrofusarin- 6-glucoside (39.4%), were obtained from the ethyl acetate fraction, and two active compounds, questin (97.9%) and chryso-obtusin (53.8%), were isolated from the chloroform fraction.

Mutagenic and carcinogenic heterocyclic amines as affected by muscle types/skin and cooking in pan-roasted mackerel.

The dependence on muscle types/skin and on degrees of cooking in the formation of heterocyclic amines (HCAs) of pan-roasted mackerel was studied. High levels of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) were found in very well done skin and ordinary muscle, being 4.2 and 5.3 ng/g, followed by 2-amino-3,4-dimethylimidazo[4,5-f] quinoxaline (MeIQx), being 1.8 and 2.1 ng/g and 2-amino-9H-pyrido[2,3-b]indole (AalphaC), being 1.2 and 2.8 ng/g, respectively. In pan-roasted mackerel, ordinary muscles contributed much more greatly to the formation of HCAs than skins due to its higher HCA contents and composition (76.1%).