米田 千恵

<p>1．コシヒカリおよびあさひの夢を試料とし，マイタケ抽出液を用いて飯を調製した．官能評価では，水で炊飯した飯に比べてコシヒカリのマイタケ飯は粘りが強く，あさひの夢では軟らかく，つやおよび粘りが強いと評価された．物性測定ではいずれの品種においても粒全体の硬さが低下した．コシヒカリを試料とし，浸漬のみのマイタケ抽出液の利用でも飯の物性向上が見られ，浸漬および加熱の両方でマイタケ抽出液を用いることで冷蔵後の物性も改善した．</p><p>2．米をマイタケ抽出液に50℃で1時間浸漬すると，米からの溶出タンパク質量が増加し，プロテアーゼ阻害剤のぺプスタチン添加により溶出が抑えられた．浸漬液のSDS-PAGE分析では，マイタケの金属プロテアーゼによるグルテリン酸性サブユニットの部分分解が認められた．さらに遊離アミノ酸の分析において疎水性アミノ酸が多く遊離していたことから，エンド型，エキソ型両方の金属プロテアーゼが炊飯時の米のタンパク質を分解し，飯の物性変化に関与していることが示唆された．</p>

<p> 低アミロース巨大胚品種（金のいぶき），低アミロース品種（たきたて），普通種（ひとめぼれ）の3品種の玄米を試料とし，生米および浸漬1時間後に炊飯する白米の常法で調製した玄米飯の成分分析を行い，物性ならびに食味に与える影響を調べた。また比較として24時間浸漬をして炊飯した玄米飯の物性および食味も調べた。通常浸漬炊飯において，金のいぶきはたきたて，ひとめぼれに比べて炊飯過程における吸水率が高く，溶出固形物量が多く，外皮が破裂する米粒の割合も高かった。また遊離糖および遊離アミノ酸量も生米，飯のいずれも金のいぶきが最も多かった。物性測定ならびに官能評価では24時間浸漬をした飯において3品種間の違いが明瞭になり，金のいぶきは物性および食味の評価が向上し，低アミロース米の特徴と巨大胚芽米であることの影響が顕著に示されることが明らかとなった。</p>

<p>Chiba University has carried out a student exchange program called "Twin college envoys (TWINCLE)" as part of Japan's re-inventory project with the support of MEXT since 2012. The TWINCLE program has 12 partner universities in 5 ASEAN countries—Indonesia, Thailand, Singapore, Cambodia, and Vietnam. During the 5 years of the program, 246 ASEAN students visited Japan. This study analyzes the effect of the program, focused on the influence on the careers of ASEAN students through the program activities, using students' comments in activity reports from 2013 to 2016 using text-mining methods and subsequently cluster analysis methods. The results suggest that ASEAN students were interested in each activity in the TWINCLE program and had good impressions after participating in the program.</p>

<p>The TWINCLE program is a teacher internship program which aims to enhance mutual understanding of foreign cultures and to develop students' ability to succeed in overseas internships. In this study, reports written by students who participated in the program were analyzed by a text mining method to evaluate the changes in their ideas about the development and practice of the teaching materials. The results indicate that the students' attitudes towards science classes changed from 'simple lecture oriented classes' to 'problem-solving learning oriented classes'. Therefore, participating in the TWINCLE program is an effective way to change the students' image of the science class.</p>

The taste and extractive components of boiled dorsal muscle and broth prepared from half-smooth golden puffer Lagocephalus spadiceus caught in Japan and from those imported from China were compared. In the sensory test, the first taste, elasticity, and saltiness of boiled muscle from Japanese (domestic) fish were higher than those of the imported fish, whereas the orthonasal fishy smell of the imported fish was higher than that of the domestic fish. The first taste, aftertaste, retronasal fishy smell, sweetness, saltiness, and umami of the broth prepared from dorsal muscle of the domestic fish were higher than those of the imported fish, whereas orthonasal fishy smell and bitterness of the imported fish were higher than those of the domestic fish. Most panelists preferred the overall taste of the domestic fish to that of the imported fish. The concentration of trimethylamine in the trichloroacetic acid extracts from boiled muscle and broth of the imported fish was higher than that of the domestic fish, suggesting that this substance contributes to the orthonasal fishy smell of the imported fish.

北海道厚岸産シングルシード方式による養殖マガキ成分の季節変化について調べた。産卵期後の2004年8月および2005年9月の試料は軟体部重量ならびに軟体指数ともに最低となった。タンパク質は産卵期前後の試料で最高になった。グリコーゲンは産卵期前後の試料で10%以下(乾重量換算)であったが,秋から春にかけては20%以上となった。ATPおよび関連化合物の総量は,11月に最高となり9月に最低となった。遊離アミノ酸総量は,6月に最高となり,9月に最低となった。主要なアミノ酸はタウリンが最も多く,次いでアラニン,プロリン,グリシン,グルタミン酸の含量が高かった。9月および11月のマガキから調製したエキスの官能検査の結果,11月のエキスは,まろやかさが強く,苦味が弱いことが示された。

With the support of JST we carried out research into developing a study program, "Fostering Next-Generation Scientists". This program for fostering talented young scientists, which was created by Chiba University, selects and trains participants in two stages. The program offers its participants the opportunity to experience advanced lectures and conduct experiments in the fields of Physics, Chemistry, Mathematics, Engineering, and Life Sciences. We are currently carrying out courses from the first to the third stage. There were 470 applicants for the program, of which 28 have completed the whole curriculum. Those who completed the program have given presentations on their research. They have also entered scientific essay competitions and won various awards such as a prize for excellence. Chiba University's program for fostering talented young scientists has been effective in selecting and developing the talents of students with a spirit of independence and perseverance.

冷凍メバチ肉の塊を,30℃ の3%食塩水に浸漬する解凍法(解凍法1),30℃ の水に浸漬する解凍法(解凍法2)および4℃ での緩慢解凍(解凍法3)に供した。品質の同じ試料では,解凍過程における重量変化,色は解凍法1と解凍法2の間で差異はみられなかった。上物とよばれる品質の高いマグロ肉についての官能検査では, 解凍法1 で解凍した試料は解凍法2で解凍したものに比べて,水っぽくなく,一方で,粘性,塩味,マグロらしい味(うま味)が強かった。解凍法1で解凍した刺身の外側の食塩濃度は,解凍法2および解凍法3で解凍した試料の食塩濃度よりも有意に高かった。マグロ肉へ食塩が浸透することによって,粘性が増し,うま味が増強されるものと考えられた。

イカ肉および表皮の物性変化と主要構成成分であるタンパク質との関わりを検討することを目的として,アオリイカ,スルメイカ,ヤリイカを4℃で0,1,2,5日間貯蔵し,生および加熱した胴肉および表皮1,2層について,物性,コラーゲン量,DSCの測定を行い,種類および貯蔵条件の異なるイカの熱的挙動を調べた。いずれのイカ胴肉も,加熱により生肉より硬く,弾力が強くなった。貯蔵により,いずれの胴肉も加熱,生ともに引張強度が低下した。ヤリイカのコラーゲン総量は他に比べて少ないが,生,加熱ともに貯蔵に伴う変化は見られなかった。DSCはいずれの胴肉においても,アクチンのピークが貯蔵に伴い低温側に移動した。したがって,生,加熱胴肉の貯蔵に伴うテクスチャーの軟化には,筋原線維の構造変化の関与が考えられる。一方,イカ表皮は,いずれのイカも加熱により生より引張強度が低下した。貯蔵に伴いスルメイカとヤリイカの引っ張り強度は生,加熱ともに低下し,特にスルメの変化が顕著であった。表皮のコラーゲン総量はヤリイカで若干少なかった。スルメイカとヤリイカの20℃および70℃可溶性コラーゲン量は,貯蔵に伴い増加した。DSCパターンはスルメイカが他と異なっていた。生および加熱イカ表皮の貯蔵に伴うテクスチャーの脆弱化には,可溶化にみられるようなコラーゲンの構造変化が関与しているものと考えられる。

Chie Yoneda Midori Kasai Keiko Hatae Yukiko Hirota Jun Nakamura Frozen blocks of bigeye tuna meat were thawed by three different methods: 1) slow thawing at 2°C for 24h and then at 20°C for 1h; 2) soaking in 3% salt water at 30°C for 1min, and then thawing at 2°C for 3h and finally at 20°C for 1h; 3) microwave irradiation for 3min while cooling at -20°C, and then thawing at 2°C for 1h and finally at 20°C for 1h. The quality of tuna meat thawed by each method was then examined. Parameters such as the proportional weight decrease, color change (a^*, b^*), and temperature change were related with the thawing rate. The final temperature of the tuna meat samples microwave thawed by methods 3 was significantly higher than that thawed by soaking in warm-salt water (methods 2). The pH value, molar percentage of ATP and related compounds, and toughness of the thawed meat were more affected by the freshness of the tuna meat than by the thawing method. A sensory test revealed that the tuna meat slowly thawed by methods 1 was darker than that thawed by the other two methods.

The extractive components of raw and boiled-dried scallop adductor muscle were examined. On a dry weight basis the levels of total free amino acids, total adenosine triphosphate (ATP) and related compounds, and betaines in the boiled-dried sample were lower than those in the raw muscle, which may have been due to the outflow of these compounds during boiling. Soup prepared from the boiled-dried scallop and chicken leg meat was assessed by sensory evaluation. This soup cooked with the scallop and chicken was stronger in sweetness, umami and body and rated higher in overall preference than the soup containing these ingredients after cooking separately. The inosine monophosphate (IMP) level in the former soup was 4.4 times higher than that in the latter. The adenosine monophosphate (AMP) deaminase (EC 3.5.4.6) activity in the crude extract from the chicken meat was 9.16 units 1(-1), whereas no activity could be detected in the crude extract from the boiled-dried scallop. It is concluded that AMP, which was mainly derived from the boiled-dried scallop, was converted to IMP by AMP deaminase from the chicken meat during the preparation of the soup, resulting in an improvement in the taste. (c) 2004 Society of Chemical Industry.

A questionnaire survey was conducted on 1771 students in the age range of 15～23 years to investigate their fruit preference. The response to each question on fruit preference was rated on a scale of nine. The questionnaire also included the question on the ease of eating of 13 kinds of fruit, and the water content and content ratio of sugar and organic acids were also examined. Pear was most preferred, followed by peach and strawberry, while persimmon was most disliked, followed by summer-orange and grapefruit. Female students preferred pear, peach, strawberry and orange, while male students preferred grape, persimmon, melon and banana. A significant correlation was recognized between the ease of eating and the fruit preference. However, pear and peach were liked, although they are not easy to eat. The water content was lowest in persimmon, and highest in strawberry, pear and peach. The content ratio of sugar to organic acids was lowest in summer-orange and grapefruit, and highest in persimmon. The water content and content ratio of sugar to organic acids are therefore considered to affect the fruit preference.

Dried squid were prepared at 4 or 40degreesC and softened first in water and then in alkaline solution. The physicochemical and structural changes in the dried squid during the softening treatment were,e examined. A significantly higher wet weight was observed for the 4degreesC-dried squid during the softening treatment compared with the 40degreesC-dried squid. The rupture stress and rupture energy of the 40degreesC-dried squid were significantly higher than those of the 4degreesC-dried squid during the softening treatment. The sodium dodecyl sulphate polyacrylamide slab gel electrophoresis (SDS-PAGE) pattern of the 4degreesC-dried squid was almost the same as that of raw squid. The SDS-PAGE pattern of the 40degreesC-dried squid showed many fragments of lower molecular weight. After soaking in distilled water the SDS-PAGE pattern of the 40degreesC-dried squid did not change significantly; however, the SDS-PAGE pattern of the 4degreesC-dried squid became the same as that of the 40degreesC-dried squid. Histological analysis by light microscopy showed the formation of muscle fibre bundles in the 40degreesC-dried squid. A higher water permeation was observed among the muscle fibres of the alkali-softened 4degreesC-dried squid when compared with the alkali-softened 40degreesC-dried squid. (C) 2003 Society of Chemical Industry.

Physicochemical changes of Japanese cockle foot parts occurring during cooking and cold storage at 4degreesC for 10 days were examined. Raw samples decreased in weight by 27% during cooking at 85degreesC for 15 s. Both raw and cooked samples decreased in weight to the same extent of 22-23% during the 10-day cold storage. The levels of ATP and related compounds, as well as those of free amino acids, were higher in raw than in cooked samples, although the former were found by sensory evaluation to have a stronger fishy odor. Raw samples started to decrease in ATP content after 5 days of cold storage, showing K' values of 18 and 42% after 5 and 7 days, respectively. The L* value in the Hunter scale color evaluation increased during the cold storage of raw samples, revealing a gradual disappearance of its original purple-gray color. Meanwhile, the L* value of cooked samples remained constant during the cold storage. The tensile strength of cooked samples was significantly higher than those of both raw samples before and after the cold storage, indicating increased toughness by cooking.

The present study examined the changes in texture and protein components during cold storage of different squid varieties. Raw oval squid, Japanese common squid and arrow squid were sliced fresh and the muscles were stored at 4degreesC for 0, 4, 8, 12, 18, 24, 48 and 120 h. The rheological measurements, protein components and amounts of collagen were examined. The adhesiveness of each squid increased significantly in the early stage of cold storage. In all varieties, penetration decreased at 4 h, which is considered to be rigor mortis, then increased. The amounts of total collagen, 20degreesC water-soluble collagen and 70degreesC water-soluble collagen did not change significantly in each variety during cold storage. Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) pattern showed that the 580 kDa component gradually disappeared up to 48 h. The correlations between the amounts of 580 kDa component and adhesiveness or firmness were high. Models of fit based on chemical kinetics accurately expressed the behavior of adhesiveness, firmness and penetration showing that 63.2% of adhesiveness changes occurred in 13-19 h and that 63.2% of firmness changes occurred in 18-24 h.

Cockle is popular in sushi bars and restaurants, the purple-gray color of the cockle's edible part being a characteristic feature as well as its taste and unique texture. Raw shellfish are generally preferred to cooked ones in Japan, although, raw cockle is not often eaten as sashimi and sushi. The reasons why cockle is blanched and then frozen are that it has unstable color pigments and is difficult to keep freshness. In this study, we stored raw cockle at low temperature (4℃) when wrapped in a humidity stabilizing sheet containing glycerol, pulp and an absorbing polymer and examined the quality change during storage. The raw sample wrapped in the humidity stabilizing sheet lost weight during storage because of dehydration. Additionally, the surface of the sample increased in toughness and decreased in chewability. The sample stored without wrapping soon decolorized and became faded. Changes in the average amount of ATP and its related compounds and in the freshness indices indicate that the storage wrapped in the sheet were superior to that without wrapping. Sensory tests also show that storage while wrapped kept the sample's fresh appearance for a longer time than without wrapping.

The antisera were raised against pepsin-solubilized abalone collagen and its corresponding gelatin. The reactivity against abalone collagen was higher with the anti-collagen than anti-gelatin antiserum. The two antisera recognized all type I collagens from various vertebrates, whereas these had no reactivity against vertebrate type III and type V collagens. Furthermore, both antisera reacted with only alpha 2(I) chains from chicken, rat, and calf. The strong reactivity was observed against the two antisera in the case of invertebrate and protochordate collagens, especially for turban shell collagen. The seasonal changes of collagen mRNA levels were examined in relation to those of collagen content. Haliotis discus collagens (Hdcols) 1 alpha and 2 alpha coding for abalone collagen pro alpha-chains showed quite similar patterns. The highest mRNA levels in adductor and foot muscles for the two collagens were observed in December and January, in good agreement with the ina rase of collagen content. The mRNA levels decreased in July and August when collagen content decreased. These results indicate that collagen transcription levels are closely related to collagen contents. (C) 2000 Elsevier Science Inc. All rights reserved.

Acid-soluble collagens were prepared from connective tissues in the abalone Haliotis discus foot and adductor muscles with limited proteolysis using pepsin. Collagen preparation solubilized with 1% pepsin contained two types of ct-chains which were different in their N-terminal amino acid sequences. Accordingly, two types of full-length cDNAs coding for collagen pro alpha-chains were isolated from the foot muscle of the same animal and these proteins were named Hdcols (Haliotis discus collagens) la and 2 alpha. The two N-terminal amino acid sequences of the abalone pepsin-solubilized collagen preparation corresponded to either of the two sequences deduced from the cDNA clones. In addition, several tryptic peptides prepared from the pepsin-solubilized collagen and fractionated by HPLC showed N-terminal amino acid sequences identical to those deduced from the two cDNA clones. Hdcols 1 alpha and 2 alpha consisted of 1378 and 1439 amino acids, respectively, showing the primary structure typical to those of fibril-forming collagens. The N-terminal propeptides of the two collagen proa-chains contained cysteine-rich globular domains. It is of note that Hdcol l alpha completely lacked a short Gly-X-Y triplet repeat sequence in its propeptide, An unusual structure such as this has never before been reported for any fibril-forming collagen. The main triple-helical domains for both chains consisted of 1014 amino acids, where a supposed glycine residue in the triplet at the 598th position from the N-terminus was replaced by alanine in Hdcol la and by serine in Hdcol 2a. Both proa-chains of abalone collagens contained six cysteine residues in the carboxyl-terminal propeptide, lacking two cysteine residues usually found in vertebrate collagens. Northern blot analysis demonstrated that the mRNA levels of Hdcols 1 alpha and 2 alpha in various tissues including muscles were similar to each other.

Two-dimensional electrophoretic gel profiles were compared between rat 3Y1 fibroblasts cultured in the presence and absence of 30 mM L-carnosine (beta-alanyl-L-histidine) for one week without any replenishment of medium. While a number of cellular proteins changed their expression levels by the addition of carnosine, we identified one of the most prominently varied proteins as vimentin, Immunoblot analysis with anti-vimentin antibody demonstrated that the vimentin levels increased about 2-fold after one-week culture in the presence of carnosine. We also confirmed that the increase of vimentin expression was dependent on the concentration of carnosine added to the medium. Moreover, when cultured cells were stained with anti-vimentin antibody and observed by light microscopy, most cells grown in the presence of carnosine were found to have markedly developed vimentin filaments, The increase of vimentin expression was also observed by adding with carnosine related dipeptides, N-acetylcanosine and anserine.

A 148 kDa protein which possibly participates in collagen metabolism was isolated from the adductor muscle of the abalone Haliotis discus, by a series of chromatographic procedures involving DEAE-Toyopearl 650 M ion exchange, TSK G3000SWG gel filtration, and Butyl-Toyopearl 650 M hydrophobic columns. Reactivity with collagen was measured as the ability to solubilize the film containing pepsin-solubilized collagen from the same animal. Active fractions of various purification steps solubilized the film at 37 degrees C within 60 min. The purified protein consisted of a single polypeptide chain and the molecular weight was estimated by SDS-PAGE to be 148,000. This protein did not contain methionine and half-cystine, and its N-terminal amino acid sequence differed from any sequences of known collagenases.

Abalone meat was cooked for 0, 15, 30, 60, 180, and 360 min, and changes in the taste and texture during cooking were studied. During cooking, the weight of meat decreased, and it was 65% of the original weight after cooking for 360 min. Collagen content in the meat decreased with a concomitant decrease in the hardness of meat (r=0.82). The amount of adenosine 5'-monophosphate increased after cooking for 15 min and leveled off. The total amount of free amino acids increased after 15-30 min, then decreased. On the contrary, the amount of oligopeptide-bound amino acids kept increasing until 360 min, both in the cooked meat and the drip. In the dominant amino acids of the oligopeptides, collagen constituents amino acids such as glycine, hydroxyproline, and proline were included. By the sensory test, the characteristic abalone taste and odor became stronger as the cooking time increased. This might be the reason why Japanese cookbooks recommend cooking for an extended period such as 15 or 180 min.