High-performance liquid chromatography analysis of naturally occurring D-amino acids in sake

We measured all of the D- and L-amino acids in 141 bottles of sakes using HPLC. We used two precolumn derivatization methods of amino acid enantiomer detection with o-phthalaldehyde and N-acetyl-L-cysteine, as well as (+)-1-(9-fluorenyl)ethyl chloroformate/1-aminoadamantane and one postcolumn derivatization method with o-phthalaldehyde and N-acetyl-L-cysteine. We found that the sakes contained the D-amino acids forms of Ala, Asn, Asp, Arg, Glu, Gln, His, Ile, Leu, Lys, Ser, Tyr, Val, Phe, and Pro. We were not able to detect D-Met, D-Thr D-Trp in any of the sakes analyzed. The most abundant D-Ala, D-Asp, and D-Glu ranged from 66.9 to 524.3 μM corresponding to relative 34.4, 12.0, and 14.6% D-enantiomer. The basic parameters that generally determine the taste of sake such as the sake meter value (SMV; "Nihonshudo"), acidity ("Sando"), amino acid value ("Aminosando"), alcohol content by volume, and rice species of raw material show no significant relationship to the D-amino acid content of sake. The brewing water ("Shikomimizu") and brewing process had effects on the D-amino acid content of the sakes: the D-amino acid contents of the sakes brewed with deep-sea water "Kaiyoushinosousui", "Kimoto yeast starter", "Yamahaimoto", and the long aging process "Choukijukusei" are high compared with those of other sakes analyzed. Additionally, the D-amino acid content of sakes that were brewed with the adenine auxotroph of sake yeast ("Sekishoku seishu kobo", Saccharomyces cerevisiae) without pasteurization ("Hiire") increased after storage at 25 °C for three months.     

Bottle-choice tests in Sprague-Dawley rats using liquid diets that differ in oil and sucrose contents

Bottle choice tests using liquid diets were done with Sprague-Dawley (SD) rats. SD rats ingested more oil-and-sucrose-enriched milk (hi-fat) and less oil-enriched milk (hi-fat-no-carb) than sucrose-enriched (hi-carb) milk by two-bottle choice tests after they were habituated to liquid diets for 4 days. Chronic food restriction didn't increase hi-fat ingestion but hi-fat-no-carb. Rats ingested less without habituation, and overnight food deprivation increased intake. This increment was maintained after rats were free-fed. The difference in fat content of the maintenance diet had little effect on fat preference. These results showed SD rats prefer a sweet and fatty liquid diet than a sweet and lean liquid diet. Habituation and food restriction were more important than the composition of the maintenance diet to demonstrate a clear preference for the fatty liquid diet.     

Phleichrome; A New Phytotoxic Compound Produced by Cladosporium phlei

Bottle choice tests using liquid diets were done with Sprague-Dawley (SD) rats. SD rats ingested more oil-and-sucrose-enriched milk (hi-fat) and less oil-enriched milk (hi-fat-no-carb) than sucrose-enriched (hi-carb) milk by two-bottle choice tests after they were habituated to liquid diets for 4 days. Chronic food restriction didn't increase hi-fat ingestion but hi-fat-no-carb. Rats ingested less without habituation, and overnight food deprivation increased intake. This increment was maintained after rats were free-fed. The difference in fat content of the maintenance diet had little effect on fat preference. These results showed SD rats prefer a sweet and fatty liquid diet than a sweet and lean liquid diet. Habituation and food restriction were more important than the composition of the maintenance diet to demonstrate a clear preference for the fatty liquid diet.     

Late-maturing cooking rice Sensyuraku has excellent properties,equivalent to sake rice,for high-quality sake brewing

Low protein content and sufficient grain rigidity are desired properties for the rice used in high-quality sake brewing such as Daiginjo-shu (polishing ratio of the rice, less than 50%). Two kinds of rice, sake rice (SR) and cooking rice (CR), have been used for sake brewing. Compared with those of SR, analyses of CR for high-quality sake brewing using highly polished rice have been limited. Here we described the original screening of late-maturing CR Sensyuraku (SEN) as rice with low protein content and characterization of its properties for high-quality sake brewing. The protein content of SEN was lower than those of SR Gohyakumangoku (GOM) and CR Yukinosei (YUK), and its grain rigidity was higher than that of GOM. The excellent properties of SEN with respect to both water-adsorption and enzyme digestibility were confirmed using a Rapid Visco Analyzer (RVA). Further, we confirmed a clear taste of sake produced from SEN by sensory evaluation. Thus, SEN has excellent properties, equivalent to those of SR, for high-quality sake brewing.     

Effect of koji starter on metabolites in Japanese alcoholic beverage sake made from the sake rice Koshitanrei

ABSTRACT

In sake brewing, the steamed rice is used in 2 ways, added to sake-mash and making rice-koji. Rice-koji is made from the steamed rice by using koji starter, and its quality is an important determinant of the aroma/taste of sake. The sake rice Koshitanrei (KOS) was developed in Niigata Prefecture by crossing 2 sake rice varieties, Gohyakumangoku and Yamadanishiki. Recently, we reported the characteristic components/metabolites in sake made from KOS by conducting metabolome analysis using UPLC-QTOF-MS. In this study, to investigate the effect of koji starter and sake rice cultivars on the sake metabolites, we performed small-scale sake-making tests using the above 3 rice cultivars and 3 koji starters. Finally, we demonstrated that some of the characteristic components/metabolites of sake from KOS are affected by the koji starter. Thus, in addition to rice cultivar, koji starter plays an important role for establishment/maintenance of the quality of the final product.     

Salt Appetite Is Reduced by a Single Experience of Drinking Hypertonic Saline in the Adult Rat

Salt appetite, the primordial instinct to favorably ingest salty substances, represents a vital evolutionary important drive to successfully maintain body fluid and electrolyte homeostasis. This innate instinct was shown here in Sprague-Dawley rats by increased ingestion of isotonic saline (IS) over water in fluid intake tests. However, this appetitive stimulus was fundamentally transformed into a powerfully aversive one by increasing the salt content of drinking fluid from IS to hypertonic saline (2% w/v NaCl, HS) in intake tests. Rats ingested HS similar to IS when given no choice in one-bottle tests and previous studies have indicated that this may modify salt appetite. We thus investigated if a single 24 h experience of ingesting IS or HS, dehydration (DH) or 4% high salt food (HSD) altered salt preference. Here we show that 24 h of ingesting IS and HS solutions, but not DH or HSD, robustly transformed salt appetite in rats when tested 7 days and 35 days later. Using two-bottle tests rats previously exposed to IS preferred neither IS or water, whereas rats exposed to HS showed aversion to IS. Responses to sweet solutions (1% sucrose) were not different in two-bottle tests with water, suggesting that salt was the primary aversive taste pathway recruited in this model. Inducing thirst by subcutaneous administration of angiotensin II did not overcome this salt aversion. We hypothesised that this behavior results from altered gene expression in brain structures important in thirst and salt appetite. Thus we also report here lasting changes in mRNAs for markers of neuronal activity, peptide hormones and neuronal plasticity in supraoptic and paraventricular nuclei of the hypothalamus following rehydration after both DH and HS. These results indicate that a single experience of drinking HS is a memorable one, with long-term changes in gene expression accompanying this aversion to salty solutions.     

Principal component analysis of the relationship between the d-amino acid concentrations and the taste of the sake

We performed sensory evaluations on 141 bottles of sake and analyzed the relationship between the d-amino acid concentrations, and the taste of the sake using principal component analysis, which yielded seven principal components (PC1–7) that explained 100 % of the total variance in the data. PC1, which explains 33.6 % of the total variance, correlates most positively with strong taste and most negatively with balanced tastes. PC2, which explains 54.4 % of the total variance, correlates most positively with a sweet taste and most negatively with bitter and sour tastes. Sakes brewed with “Kimoto yeast starter” and “Yamahaimoto” had high scores for PC1 and PC2, and had strong taste in comparison with sakes brewed with “Sokujo-moto”. When present at concentrations below 50 μM, d-Ala did not affect the PC1 score, but all the sakes showed a high PC1 score, when the d-Ala was above 100 μM. Similar observations were found for the d-Asp and d-Glu concentrations with regard to PC1, and the threshold concentrations of d-Asp and d-Glu that affected the taste were 33.8 and 33.3 μM, respectively. Certain bacteria present in sake, especially lactic acid bacteria, produce d-Ala, d-Asp and d-Glu during storage, and these d-amino acids increased the PC1 score and produced a strong taste (Nojun). When d- and l-Ala were added to the sakes, the value for the umami taste in the sensory evaluation increased, with the effect of d-Ala being much stronger than that of l-Ala. The addition of 50–5,000 μM dl-Ala did not effect on the aroma of the sakes at all.     

Role of insulin and counter-regulatory hormones in the metabolic changes caused by insulin deprivation in diabetic patients

In eight insulin dependent diabetic patients treated by continuous subcutaneous insulin infusion (1.1 +/- 0.2 U/h), the levels (measured hourly from 23 h to 05 h) of blood glucose, non esterified fatty acids (NEFA), glycerol and 3-OH-butyrate (3-OH-B) have been correlated to the circulating levels of free insulin (FIRI), glucagon, growth hormone or cortisol, in two experimental conditions: A. Insulin being infused as usual (physiological FIRI levels) and B. Progressively declining FIRI levels (insulin infusion arrested at 23 h). In condition A, blood glucose levels correlated significantly to both insulin and glucagon; NEFA, glycerol and 3OH-B correlated only to insulin. In condition B, blood glucose was significantly correlated to insulin but not to glucagon while NEFA, glycerol and 3-OH-B were significantly correlated to both hormones but not to growth hormone or cortisol. Therefore, on the metabolic deterioration that follows insulin withdrawal, growth hormone and cortisol seem to play a minor role, the main role being played by the decrease in circulating insulin levels and to a lesser extent by the increase in glucagon levels.     

4种抗真菌药物对糖尿病大鼠血糖的影响

目的观察酮康唑、氟康唑、伊曲康唑和特比萘芬与胰岛素组合使用以及单独使用时对糖尿病大鼠血糖水平的影响。方法建立糖尿病大鼠模型,随机分为10组,每组5只。前4组皮下注射胰岛素的同时分别喂食4种抗真菌药物;第5组单独皮下注射胰岛素;第6—9组分别喂食4种抗真菌药物;第10组既不注射胰岛素也不喂食抗真菌药物。定时对糖尿病大鼠尾静脉采血,使用CX5PRO生化检测仪对其血糖进行检测。结果酮康唑、氟康唑和伊曲康唑分别与胰岛素合用时,可使糖尿病大鼠血糖降低（P〈0．05）;不与胰岛素合用时,氟康唑和伊曲康唑均可使糖尿病大鼠血糖升高（P〈0．05）;特比萘芬无论是否与胰岛素合用,对糖尿病大鼠的血糖水平均无影响（P〉0．05）。结论唑类抗真菌药物无论是否与胰岛素合用均会影响糖尿病大鼠的血糖水平,特比萘芬无论是否与胰岛素合用,都不会影响糖尿病大鼠的血糖水平。     

Lactose metabolism in Lactobacillus curvatus and Lactobacillus sake

Abstract The lactose metabolism was investigated in five strains of Lactobacillus curvatus and 14 strains of L. sake isolated from meat or meat-derived products. Strains with the ability to ferment lactose were found in both species. They exhibited either phospho-β-galactosidase (P-β-gal) or β-galactosidase (β-gal) activity, or both. P-β-gal activity of L. curvatus and L. sake was induced and detected only in the presence of lactose or galactose. Furthermore, catabolite repression by glucose was demonstrated. The immunological properties of the P-β-gal enzymes of these organisms resemble those of Lactococcus lactis . Several strains of L. sake but none of L. curvatus exhibited β-gal activity which was constitutive. In hybridisation experiments, the β-gal genes of L. sake and L. casei ATCC393 showed over 60% DNA-homology. The presence of β-gal genes in L. sake was demonstrated in both β-gal-producing and non-producing strains. This observations is consistent with a genetic potential of lactic acid bacteria exceeding their physiological capabilities.     

Preference for dietary fat induced by release of beta-endorphin in rats

AimsTo determine whether beta-endorphin contributes to the ingestion of and preference for dietary oil, we examined the relationship between the dynamics of beta-endorphin, before and after the ingestion of corn oil, and the intake volume of corn oil.Main methodsRats were offered 5% corn oil for 20 min for 5 consecutive days so they could acquire a preference for corn oil. On day 6, seven groups of rats were presented with the oil for defined time periods, and we measured the beta-endorphin levels in the serum and cerebrospinal fluid (CSF) before and after the presentation of corn oil as well as the consumed volume of corn oil at defined time points.Key findingsBeta-endorphin levels in serum and CSF were significantly increased 15 min after the ingestion of corn oil, followed by a rapid decrease and maintenance at the basal level throughout the rest of the experimental period. The intake of corn oil was the lowest in the time period of 15–30 min, when the beta-endorphin level reached a peak value. The intake volume of corn oil might be inversely correlated with beta-endorphin levels in serum and CSF. The pretreatment of naloxone, an antagonist of the opioid receptor, decreased the initial licking rate for corn oil and increased the latency for corn oil in the licking test.SignificanceThe beta-endorphin was rapidly released after oil ingestion, which contributed to the hedonic preference and ingestive behavior for fat.     

Carbohydrate Utilization in Lactobacillus sake

The ability of Lactobacillus sake to use various carbon sources was investigated. For this purpose we developed a chemically defined medium allowing growth of L. sake and some related lactobacilli. This medium was used to determine growth rates on various carbohydrates and some nutritional requirements of L. sake. Mutants resistant to 2-deoxy-d-glucose (a nonmetabolizable glucose analog) were isolated. One mutant unable to grow on mannose and one mutant deficient in growth on mannose, fructose, and sucrose were studied by determining growth characteristics and carbohydrate uptake and phosphorylation rates. We show here that sucrose, fructose, mannose, N-acetylglucosamine, and glucose are transported and phosphorylated by the phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS). The PTS permease specific for mannose, enzyme II(supMan), was shown to be responsible for mannose, glucose, and N-acetylglucosamine transport. A second, non-PTS system, which was responsible for glucose transport, was demonstrated. Subsequent glucose metabolism involved an ATP-dependent phosphorylation. Ribose and gluconate were transported by PTS-independent permeases.     

Food Deprivation Increases the Rat's Preference for a Fatty Flavor Over a Sweet Taste

Previous research indicates that food deprivation increasesthe rat's preference for high-fat over low-fat foods. Sincethese foods differ in their flavors and post-ingestive effects,both factors may be implicated. The present study investigatedpreferences in food deprived and non-deprived rats using non-nutritivemineral oil emulsion (MO) and saccharin solution (SAC), whichhave a fatty flavor and sweet taste, respectively. The deprivedrats consumed more MO than SAC in one- and two-bottle tests,while the non-deprived rats ingested as much SAC as MO in one-bottletests and preferred SAC in two-bottle tests. Several aspectsof the data suggest that the deprivation-related shift in preferencebetween MO and SAC was determined by changes in long-term energybalance. A follow-up conditioning experiment discarded the possibilitythat the observed preference shift was related to differentialreinforcing effects of the two substances. In conclusion, long-termfood restriction increases the preference for an oily flavorover a sweet taste via a mechanism that does not involve nutritivefeedback. It remains to be determined to what extent this alterationin flavor preference influences food selection when post-ingestivenutritive feedback can influence food choice. Chem. Senses 21:169–179, 1996.     

Study of the effect of gymnemic acid on taste in hamster

Behavioral and electrophysiological experiments with 10 sweetenershave been made to test if gymnemic acid (GA) is able to blockthe response to sweet stimuli in single taste fibres of thechorda tympani proper nerve in hamsters. The hamster was chosenbecause earlier studies show that it is more sensitive to GAthan any other non-human species. Since GA has been shown toaffect the sweetness of many different substances, its effectswere studied on an array of sweeteners. To avoid, however, theinclusion of sweeteners unpalatable to the hamster, the hamsters'liking of this array was tested with two-bottle preference techniquefor –24 h. It was found that acesulfam-K, fructose, glucose,sucrose and xylitol were strongly liked, while the animals showedno preference for aspartame, D-tryptophane, sodium cyclamate,sodium saccharin and thaumatin over water. The summated nerveresponse of these stimuli was then recorded. It was found thatneither thaumatin nor aspartame elicited a response, while theother stimuli gave a good response. Finally, the sweetenerswhich were both preferred in the two-bottle tests and gave anerve response were used as taste stimuli in single fibre experimentstogether with sodium chloride, quinine hydrochloride, citricacid and saccharin. The single fibre recordings were made beforeand after application of 5 mg GA for 3 min on the tongue. Itwas found that GA did not cause any dramatic decrease or disappearanceof the responses to either the sweet or the non-sweet substances.The responses to the sweeteners, however, were more depressedthan those to the non-sweet stimuli.     

Obesity by choice: the powerful influence of nutrient availability on nutrient intake

The consumption of nutrients by rodents is markedly influenced by the number of containers of each nutrient provided. Most rats given a choice from separate sources of protein, carbohydrate, and fat thrived if given one cup of each but half failed to thrive if given one cup of each and three extra cups of carbohydrate or fat. Rats given five bottles of sucrose solution and one bottle of water became fatter than rats given five bottles of water and one of sucrose. These studies in rats may point to a model for human obesity, in which the availability of food can override physiological controls of ingestion.     

Rapid post-oral stimulation of intake and flavor conditioning by glucose and fat in the mouse

Although widely assumed to have only satiating actions, nutrients in the gut can also condition increases in intake in some cases. Here we studied the time course of post-oral nutrient stimulation of ingestion in food-restricted C57BL/6J mice. In experiment 1, mice adapted to drink a 0.8% sucralose solution 1 h/day, rapidly increased their rate of licking (within 4-6 min) when first tested with an 8% glucose solution and even more so in tests 2 and 3. Other mice decreased their licking rate when switched from sucralose to 8% fructose, a sugar that is sweet like glucose but lacks positive post-oral effects in mice. The glucose-stimulated drinking is due to the sugar's post-oral rather than taste properties, because sucralose is highly preferred to glucose and fructose in brief choice tests. A second experiment showed that the glucose-stimulated ingestion is associated with a conditioned flavor preference in both intact and capsaicin-treated mice. This indicates that the post-oral stimulatory action of glucose is not mediated by capsaicin-sensitive visceral afferents. In experiment 3, mice consumed flavored saccharin solutions as they self-infused water or glucose via an intragastric (IG) catheter. The glucose self-infusion stimulated ingestion within 13-15 min in test 1 and produced a conditioned increase in licking that was apparent in the initial minute of tests 2 and 3. Experiment 4 revealed that IG self-infusions of a fat emulsion also resulted in post-oral stimulation of licking in test 1 and conditioned increases in tests 2 and 3. These findings indicate that glucose and fat can generate stimulatory post-oral signals early in a feeding session that increase ongoing ingestion and condition increases in flavor acceptance and preference revealed in subsequent feeding sessions. The test procedures developed here can be used to investigate the peripheral and central processes involved in stimulation of intake by post-oral nutrients.     

Modulation of A and B cell functions by tolbutamide and arginine in the pancreas of thiamine-deficient rats

The effects of administration of glucose orally and tolbutamide or arginine intravenously on insulin and glucagon secretion and blood glucose level were studied in normal and thiamine-deficient rats. In thiamine deficiency, insulin secretion and glucose tolerance were impaired during glucose ingestion. Tolbutamide decreased the blood glucose level in both control and thiamine-deficient rats but its stimulatory effect on insulin secretion was minimal in thiamine-deficient rats unlike the control animals. Arginine did not alter substantially the blood glucose or insulin in thiamine-deficient rats, whereas it increased the insulin level in control rats. The fasting plasma glucagon level was high in thiamine deficiency. Tolbutamide increased the plasma glucagon in control rats, but did so only marginally in thiamine-deficient rats. Arginine also increased the glucagon secretion throughout the period of study in control rats. In thiamine-deficient rats the glucagon secretion was pronounced only after 20 min of arginine administration. These results suggest that an unimpaired glucose metabolism is a prerequisite to induce proper insulin secretion. Only proper insulin secretion can check the glucagon secretion rather than the increased glucose level. Hypoglycemia can induce glucagon secretion independent of the insulin level.     

Identification of alpha-D-glucosylglycerol in sake

alpha-D-Glucosylglycerol (GG) was found for the first time in sake (Japanese rice wine) in an amount of about 0.5%. GG was also found in miso and mirin which had been brewed by using koji. GG was hydrolyzed into glucose and glycerol in an equimolar ratio with maltase (EC 3.2.1.20, alpha-glucosidase from yeast), but not with emulsin (EC 3.2.1.21, beta-glucosidase from almond). The retention times and mass spectra of trimethylsilyl derivatives by a GC-MS analysis of GG in sake were comparable to those of various GG samples synthesized by glycol cleavage. It was proven that GG in sake consisted of three components, viz., 2-O-alpha-D-glucosyl-glycerol (GG-II), (2R)-1-O-alpha-D-glucosylglycerol (R-GG-I) and (2S)-1-O-alpha-D-glucosylglycerol (S-GG-I). The ratio of the three components in GG was 6:66:28 for sake. It is considered that GG was formed by transglucosylation of the glucosyl groups to glycerol by alpha-glucosidase from koji in the sake mash.