島田 良子

本研究では, 岩牡蠣を地域ブランド食品としてPRするための基礎資料を得ることを目的に, 牡蠣生産地の若年者における牡蠣類とその特徴の認知度や, 一般的な牡蠣類とその特徴の認知度について, 質問紙調査により明らかにした. 調査はわが国における主要な牡蠣類の生産地である長崎県, 兵庫県, 宮城県および広島県において, 将来的な岩牡蠣の購買層になり得る学生 (若年者) を対象に実施した. 岩牡蠣の認知度は, 若年回答者の約4割で, その食経験がある者の割合は2割未満であり, 岩牡蠣を知らない, あるいは食べたことがない者が多いことが明らかとなった. また, 真牡蠣と比べると岩牡蠣の旬は正しく認識されておらず, その生産地もほとんど認知されていなかった. 一般に牡蠣類の栄養素等はミネラル, 牡蠣料理はフライと焼きのイメージが強いことが示された. これらの情報は, 岩牡蠣を地域ブランド食品としてPRするための方法を提案する上で, 有用な基礎資料になり得ると考える.

レジスタントスターチ・タイプ4 (RS-4) は化学修飾デンプンで, 加工デンプンの一種である. 加工デンプンは食品の物性改良を目的に使用されることが多いが, 食物繊維様の機能も有している. 本研究では, 食物繊維摂取量を増加させることを目的に, 原料デンプンの異なるRS-4を添加しても, 嗜好性が得られるのか, 物性に差が生じるのか検討した. RS-4はジャガイモ, タピオカ, コメデンプンをリン酸架橋したものとサツマイモ, コムギデンプンをリン酸モノエステル化リン酸架橋したものを用いた. これらを小麦粉の20％と置換しホームベーカリーで焼成した. なお, 小麦粉100％で焼成したパンをControlパンとした. 焼成1日後に, 比容積測定, 硬度測定, 粒度分布, SEMによるパンの構造解析, 官能評価を行った. いずれのRS-4添加パンの比容積はControlパンよりも小さく, クラムも硬かった. デンプンを架橋化するとデンプン粒の膨潤が抑制されデンプン粒が残存していたため, パンが十分に膨らまず硬さに影響したと推察された. 識別評価, 嗜好評価のいずれの項目においてもRS-4の間に差はみられなかった. 嗜好評価の結果より, RS-4を添加したパンにおいてもControlパンと同程度の嗜好性が得られたことから, いずれの RS-4を食パンへ添加しても日常的に摂取でき, 食物繊維量を増加させる素材としても有効である可能性が示唆された.

We examined whether soybean (SB) and soy protein isolate (SPI) can prevent the betaine-induced elevation of plasma cholesterol as well as maintain the betaine-induced reduction of plasma Hcy concentration. Rats were fed casein-, SB-, or SPI-based diet with or without betaine SPI-based diet with betaine containing soybean fiber (SF) or soy lecithin (SL) or the combination of SF and SL. Plasma Hcy concentration was decreased by feeding betaine to rats fed the casein-, SB-, and SPI-based diets. Betaine-induced elevation of plasma cholesterol was decreased by feeding the SB-based diet compared with the casein-based diet, but was not decreased by feeding the SPI-based diet. In rats fed the SPI-based diet, the increased concentration of plasma cholesterol by betaine feeding was not prevented by independent addition of SL or SF, but was prevented by a combination of SL and SF, and was associated with increased fecal excretion of bile acids.

In the present study, the effects of Euglena and paramylon on hyperglycemia were examined in Otsuka Long-Evans Tokushima fatty (OLETF; type 2 diabetes mellitus model) rats. OLETF rats were fed an AIN-93 M diet containing cellulose, Euglena, or paramylon for 10 weeks. Long-Evans Tokushima Otsuka (LETO) rats were used as nondiabetic controls. An oral glucose-tolerance test (OGTT) was performed at 0 and 10 weeks. OLETF control rats were obese because of bulimia and showed abdominal fat accumulation and hyperglycemia. Euglena supplementation improved hyperglycemia and decreased food intake, body weight gain, and abdominal fat. However, there were no changes in the paramylon-supplemented group compared to the OLETF control group. Triglyceride concentrations in the serum and liver were lower in Euglena-supplemented rats than in OLETF control rats. There was a correlation between hepatic triglyceride concentration and the area under the curve (AUC) of OGTT at 10 weeks. This suggests that the improvement in glycemic control in the Euglena-supplemented group may depend on substances other than paramylon present in Euglena.

Biotin is a water-soluble vitamin that functions as a cofactor for biotin-dependent carboxylases. The biochemical and physiological roles of biotin in brain regions have not yet been investigated sufficiently in vivo. Thus, in order to clarify the function of biotin in the brain, we herein examined biotin contents, biotinylated protein expression (e.g. holocarboxylases), and biotin-related gene expression in the brain of biotin-deficient rats. Three-week-old male Wistar rats were divided into a control group, biotin-deficient group, and pair-fed group. Rats were fed experimental diets from 3 wk old for 8 wk, and the cortex, hippocampus, striatum, hypothalamus, and cerebellum were then collected. In the biotin-deficient group, the maintenance of total biotin and holocarboxylases, increases in the bound form of biotin and biotinidase activity, and the expression of an unknown biotinylated protein were observed in the cortex. In other regions, total and free biotin contents decreased, holocarboxylase expression was maintained, and bound biotin and biotinidase activity remained unchanged. Biotin-related gene (pyruvate carboxylase, sodium-dependent multivitamin transporter, holocarboxylase synthetase, and biotinidase) expression in the cortex and hippocampus also remained unchanged among the dietary groups. These results suggest that biotin may be related to cortex functions by binding protein, and the effects of a biotin deficiency and the importance of biotin differ among the different brain regions.

To characterize a new function of the water-soluble vitamin, biotin, in reproduction and early growth in mammals, the effects of high dietary doses of biotin on early spermatogenesis were biochemically and histologically investigated in male rats. Weaned rats were fed a CE-2 (control) diet containing 0.00004% biotin, or a control diet supplemented with 0.01%, 0.1%, or 1.0% biotin. Pair-fed rats were fed a control diet that was equal in calories to the amount ingested by the 1.0% biotin group, because food intake was decreased in the 1.0% biotin group. Food intake and body weight gain were lower in the 1.0% biotin group than in the control group. The kidney, brain and testis weights were significantly lower in the 1.0% biotin group than in the pair-fed group after 6 weeks of feeding. The accumulation of biotin in the liver and testis increased in a dose-dependent manner. In the 1.0% biotin group, the number of mature sperm was markedly lower, that of sperm with morphologically abnormal heads, mainly consisting of round heads, had increased. In addition, the development of seminiferous tubules was inhibited, and few spermatogonia and no spermatocytes were histologically observed. These results demonstrated that the long-term intake of high-dose biotin inhibited spermatogenesis in young male rats.