關華豆膠[編輯]
| 關華豆膠 | |
|---|---|
 | |
| 識別 | |
| CAS號 | 9000-30-0 |
| ChemSpider | NA |
| ATC代碼 | A10BX01 |
| 性質 | |
| pKa | 5-7 |
| 危險性 | |
| MSDS | MSDS |
| 若非註明，所有數據均出自一般條件（25 ℃，100 kPa）下。 | |
關華豆膠（Guar gum），也叫做 瓜爾膠（guaran），是一種半乳甘露聚醣( galactomannan)。CAS登録號碼是9000-30-0。它主要是瓜爾豆的胚乳。瓜爾豆種子去殼，碾磨和篩選取得瓜爾豆膠。[1] 它通常是一種可自由流動的灰白色粉末。
特性[編輯]
- 分子量在20～30萬的時候，有血糖値上昇抑制作用、以及降低膽固醇、使排便更順暢等等的生理效果。
- 可被認可的食品添加物，廣泛用於增稠劑、安定劑。下列產品，幾乎都有使用，例如：冰淇淋、和菓子、海鮮煉製品、沙拉醬等等。還有，利用瓜爾豆酵素處理的豆酵素分解物中有水溶性食物繊維。
生產與交易[編輯]
瓜爾豆(關華豆)主要生長在印度和澳大利亞，在美國，中國和非洲的小作物。在印度的古吉拉特邦(Gujarat)、拉賈斯坦邦(Rajasthan)、和哈里亞納邦(Haryana)是主要種植區，而主要交易市場是在 Rajasthan 的三個轄區，轄區如下：Jodhpur、Sri GangaNagar、Hanumangarh。
印度每年生產10.0-12.5萬盧比噸（1 - 125萬噸）瓜爾，使印度成為最大的生產國，約佔世界總產量的80％。而在巴基斯坦，旁遮普邦是其瓜爾豆主產區。
瓜爾膠及其衍生物是世界總產量的約7萬盧比噸（700,000噸）。工業用瓜爾豆膠約佔總需求量的45％左右。它是用來作為在鑽油井中的控制劑，以方便的鑽井和防止流體損失。
在2012年，瓜爾豆價格增長了9倍至10倍。主要原因是，由於拉賈斯坦邦持續乾旱，瓜爾豆膠的短缺陷入恐懼之中，導致哈里伯頓公司之前建立的庫存產生大規模的價格上漲。
屬性[編輯]
化學式[編輯]
溶解度和粘度[編輯]
關華豆膠相較於刺槐豆膠有更好的水溶性，由於關華豆膠有較多的半乳糖支鍊，同時也是較好的安定劑。和刺槐豆膠不同，關華豆膠並不會自己形成凝膠。[2] 然而使用硼砂或者鈣可以使關華豆膠產生交聯 (Cross-linking)使其形成凝膠。在水中關華豆膠是非離子性的水狀膠體，並不會因為離子強度或pH值的改變造成結構或者性質產生變化。一般而言，在pH值介於5到7時關華豆膠結構仍然能保持穩定。但在極端的酸性或者溫度下 (如pH = 3且溫度為50 °C時)[2]關華豆膠可能會被降解。強酸會導致其水解並且使其黏度下降，而在高濃度強鹼下年度也會降低。另外，關華豆膠無法溶於大部分的有機溶劑。
Guar gum shows high low-shear viscosity but is strongly shear-thinning. It is very thixotropic above 1% concentration, but below 0.3%, the thixotropy is slight. It has much greater low-shear viscosity than that of locust bean gum, and also generally greater than that of other hydrocolloids. Guar gum shows viscosity synergy withxanthan gum. Guar gum and micellar casein mixtures can be slightly thixotropic if a biphase system forms.[2][3]
增稠[編輯]
關華豆膠的增稠效果比玉米澱粉高出接近八倍，經濟效益更為突出。添加少量即可產生足夠的黏度。因此也在很多較多相的配方中扮演重要角色：關華豆膠可以當作乳化劑使用，可以防止油滴聚集；也可以做為安定劑來防止顆粒物質沉澱。
關華豆膠是一種豆類胚乳的樹膠，其含有超過６０﹪的高分子重量的水合膠性粘多糖體叫GALACTOMANNAN，食用後胃中產生膨脹的功能。糖尿病患者可以使用關華豆膠以及藥物來減低血糖濃度。通常是在飯前使用，並約飲２００毫升的水。關華豆膠還有減低血脂肪的功能（D.J.A.JENKINS et al.,AM.J.CLIN NUTR.）
Ice crystal growth[編輯]
Guar gum retards ice crystal growth nonspecifically by slowing mass transfer across the solid/liquid interface. It shows good stability during freeze-thaw cycles.[2]
分級[編輯]
關華豆膠分析如下：
| Test | Test Method | Test | Test method |
|---|---|---|---|
| Colour | TP/09 | Acid-insoluble residue | TP/115 |
| Viscosity | TP/10/04 | Fat content | TP/18 |
| Granulation (mesh) | TP/21 | Ash content | TP/12 |
| Moisture, pH | TP/1 and TP/29 | Gum content | TP/03 |
| Protein | TP/05 | Heavy metals | TP/13 |
| Insolubles Ash | TP/11 | Filterability | TP/20A |
Guar gum powder standards are:
- HS-Code- 130 232 30
- CAS No.- 9000-30-0
- EEC No.- E 412
- BT No.- 1302 3290
- EINECS No. - 232-536-8
- Imco Code- Harmless
製造過程[編輯]
根據最終產品的要求後，使用各種處理技術。瓜爾豆膠的商業化生產，通常採用焙燒、差分減員、過篩、和拋光。
Food-grade guar gum is manufactured in stages. Guar split selection is important in this process. The split is screened to clean it and then soaked to prehydrate it in a double-cone mixer. The prehydrating stage is very important because it determines the rate of hydration of the final product.
The soaked splits, which have reasonably high moisture content, are passed through a flaker. The flaked guar split is ground and then dried. The powder is screened through rotary screens to deliver the required particle size. Oversize particles are either recycled to main ultra fine or reground in a separate regrind plant, according to the viscosity requirement.
This stage helps to reduce the load at the grinder. The soaked splits are difficult to grind. Direct grinding of those generates more heat in the grinder, which is not desired in the process, as it reduces the hydration of the product. Through the heating, grinding, and polishing process, the husk is separated from the endosperm halves and the refined guar split is obtained. Through the further grinding process, the refined guar split is then treated and converted into powder.
The split manufacturing process yields husk and germ called 「guar meal」, widely sold in the international market as cattle feed. It is high in protein and contains oil and albuminoids, about 50% in germ and about 25% in husks. The quality of the food-grade guar gum powder is defined from its particle size, rate of hydration, and microbial content. E412 guar gum is an important natural food supplement with high nutritional value.[來源請求]
Manufacturers define different grades and qualities of guar gum by the particle size, the viscosity generated with a given concentration, and the rate at which that viscosity develops. Coarse-mesh guar gums will typically, but not always, develop viscosity more slowly. They may achieve a reasonably high viscosity, but will take longer to achieve. On the other hand, they will disperse better than fine-mesh, all conditions being equal. A finer mesh, such as a 200 mesh, requires more effort to dissolve.[4]
Modified forms of guar gum are available commercially, including enzyme-modified, cationic and hydropropyl guar.[5]
工業用途[編輯]
- 紡織工業(sizing, finishing and printing)
- 造紙工業([improved sheet formation, folding and denser surface for printing)
- 製藥生技工業([as binder or as disintegrator in tablets; main ingredient in some bulk-forming laxatives)
- 化樁品化學工業([thickener in toothpastes, conditioner in shampoos (usually in a chemically modified version))
- 火藥工業(Explosives industry –as waterproofing agent mixed with ammonium nitrate, nitroglycerin, etc.)
- 油田、天然氣田
- 採礦工業(Mining)
- Hydraulic fracturing Shale oil and gas extraction industries consumes about 90% of guar gum produced from India and Pakistan. [6]
- Hydroseeding – formation of seed-bearing "guar tack"[7]
- Medical institutions, especially nursing homes - used to thicken liquids and foods for patients with dysphagia
- Fire retardant industry - as a thickener in Phos-Chek
- Nanoparticles industry - to produce silver or gold nanoparticles, or develop innovative medicine delivery mechanisms for drugs in pharmaceutical industry.
食品中的應用[編輯]
瓜爾豆膠的最大市場是在食品工業。在美國，各種食品中的應用，設置為不同百分比的其允許濃度。[8] 在歐洲，瓜爾豆膠的歐盟食品添加物號碼是E412。Xanthan gumand guar gum are the most frequently used gums in gluten-free recipes and gluten-free products.
應用領域包括：
- 在焙烤食品， it increases dough yield, gives greater resiliency, and improves texture and shelf life; in pastry fillings, it prevents "weeping" (syneresis) of the water in the filling, keeping the pastry crust crisp. It is primarily used in hypoallergenic recipes that use different types of whole-grain flours. Because the consistency of these flours allows the escape of gas released by leavening, guar gum is needed to improve the thickness of these flours, allowing them to rise as a normal flour would. [9]
- 在奶製品，it thickens milk, yogurt, kefir, and liquid cheese products, and helps maintain homogeneity and texture of ice creams and sherbets. It is used for similar purposes in plant milks.
- 至於肉類，它的功能作為粘合劑。
- In condiments, it improves the stability and appearance of salad dressings, barbecue sauces, relishes, ketchups and others.
- 在罐頭湯，它是用來作為增稠劑和穩定劑。
- It is also used in dry soups, instant oatmeal, sweet desserts, canned fish in sauce, frozen food items, and animal feed.
營養與藥用功效[編輯]
Several studies have found significant decreases in human serum cholesterol levels following guar gum ingestion. These decreases are thought to be a function of its high soluble fiber content.[來源請求]關華豆膠(瓜爾豆膠), 是一種可溶於水的可溶性纖維，acts as a bulk-forming laxative, so is claimed to be effective in promoting regular bowel movements and relievingconstipation and chronic related functional bowel ailments, such as diverticulosis, Crohn's disease, colitis and irritable bowel syndrome.
Guar gum has been considered of interest in regard to both weight loss and diabetic diets. It is a thermogenic substance.[10] Moreover, its low digestibility lends its use in recipes as a filler, which can help to provide satiety, or slow the digestion of a meal, thus lowering the glycemic index of that meal. In the late 1980s, guar gum was used and heavily promoted in several weight-loss products. The US Food and Drug Administration eventually recalled these due to reports of esophagealblockage from insufficient fluid intake, after one brand alone caused at least 10 users to be hospitalized, and a death.[11] For this reason, guar gum is no longer approved for use in over-the-counter weight loss aids in the United States. Moreover, a meta-analysis combining the results of 11 randomized, controlled trials found guar gum supplements were not effective in reducing body weight.[12]
Two Japanese studies using rats showed guar gum supports increased absorption of calcium occurring in the colon instead of in the small intestine. This means lesser amounts of calcium may be consumed to obtain its recommended minimum daily intake. This has obvious implications for reduced calorie diets, since some calcium-rich dairy products tend to be high in calories.[來源請求]
Guar gum, though, is also capable of reducing the absorbability of dietary minerals (other than calcium), when foods or nutritional supplements containing them are consumed concomitantly with it, but this is less of a concern with guar gum than with various insoluble dietary fibers.
Some studies have found guar gum to improve dietary glucose tolerance.[13] Research has revealed the water-soluble fiber in it may help people with diabetes by slowing the absorption of sugars by the small intestine. Although the rate of absorption is reduced, the amount of sugar absorbed is the same overall. This may help diabetic patients by moderating glucose "spikes".
Allergies[編輯]
Some studies have found an allergic sensitivity to guar gum developed in a few individuals working in an industrial environment where airborne concentrations of the substance were present. In those affected by the inhalation of the airborne particles, common adverse reactions were occupational rhinitis and asthma.[14]
Soy protein occurs as an impurity in manufactured guar gum, and can make up as much as 10%. The guar gum can therefore adversely affect those with sensitivity to soy.[15]
Dioxin contamination[編輯]
In July 2007, the European Commission issued a health warning to its member states after high levels of dioxins were detected in a food additive - guar gum - used as thickener in small quantities in meat, dairy, dessert or delicatessen products. The source was traced to guar gum from India that was contaminated withpentachlorophenol, a pesticide no longer in use.[16] PCP contains dioxins as contamination. Dioxins damage the human immune system.[17]
瓜爾膠
拼音：guā ěr jiāo (gua er jiao)
瓜爾膠，爲大分子天然親水膠體，主要由半乳糖和甘露糖聚合爲食品而成，屬於天然半乳甘露聚糖，品質改良劑之一，一種天然的增稠劑。外觀是從白色到微黄色的自由流動粉末，能溶於冷水或熱水，遇水後及形成膠狀物質，達到迅速增稠的功效。
簡介
瓜爾膠溶於冷水和熱水，不溶於油、油脂、烴、酮和酯。水溶液無味、無臭、無毒、呈中性。由於溶液中含有少量的纖維和纖維素，呈淡灰色半透明狀。在水中還呈現高黏性。其黏度變化取決於顆粒的大小、pH值和溫度。與其他植物膠、澱粉和水溶性蛋白質等具有相容性。由瓜爾豆籽經磨碎、篩分、吹風除皮和胚芽、胚乳處理等工序加工制成。用作增稠劑、絮凝劑、浮選劑、成膜劑和上漿劑等。
化學性質
白色至淺黄褐色自由流動的粉末。接近無臭。能分散在熱或冷的水中形成粘稠液，1%水溶液的粘度約4～5Pa?S，爲天然膠中粘度最高者。添加少量四硼酸鈉則轉變成凝膠。分散於冷水中約2h後呈現很強粘度，以後粘度逐漸增大，24h達到最高點。粘稠力爲澱粉糊的5～8倍。加熱則迅速達到最高粘度。水溶液爲中性。pH值6～8粘度最高，pH值10以上則迅速降低。pH值6.0～3.5範圍内隨pH值降低，粘度亦降低。pH值3.5以下粘度又增大。
衛生標准
中國《食品添加劑使用衛生標准》（GB2760―1996）中規定：可按生產需要適量用於各類食品中。FAO（1984）規定：用於青刀豆、黄莢刀豆、甜玉米、蘑菇、蘆筍、青豌豆等罐頭，10g/kg；加工幹酪制品，8g/kg；乳汁幹酪，5 g/kg；酪農幹酪，5 g/kg；（按稀奶油混合物計）；沙丁魚及其制品、鯖、鮐魚等罐頭，20 g/kg（按罐裝湯汁）；配置嬰兒食品，1g/kg；芥菜型酸黄瓜、肉湯、羹，按GMP ；胡蘿蔔，10g/kg；發酵後經加熱處理的增香酸奶，5g/kg；冷飲，10 g/kg（以最終產品計）。
用途
用作頭髮及皮膚的調理劑、抗靜電劑及增稠劑，適用於洗發香波、護發素。研究表明，瓜爾膠能適應現代工廠零排放的要求，在提高紙頁留着和濾水的同時能保持或提高紙頁勻度，是一種前景廣闊的環保助劑。作乳化穩定劑和增稠劑。中國規定可用於各類食品，按生產需要適量使用。
生產方法
（1） 以豆科植物瓜爾豆的種子胚乳爲原料，幹燥、粉碎後，加壓水解，然後用20%的乙醇沉澱，離心分離後幹燥、粉碎得成品。
（2）由豆科植物瓜爾豆rCyamposi5￡以一ragonolobus或c．psDraloides]的種子去皮去胚芽後的胚乳部分，幹燥粉碎後加水，進行加壓水解後用20％乙醇沉澱，離心分離後幹燥、粉碎而成。
發展
瓜爾膠的最初出現是作爲刺槐豆膠(Locustbeangum)的替代品而產生的。在此之前，刺槐豆膠被廣泛應用於工業生產並造成了需求緊張。後來研究證明，雖然瓜爾膠和刺槐豆膠均爲聚半乳糖甘露糖，但二者在化學組成和行爲上有着明顯的區别。刺槐豆膠要達到最大粘度需要高溫水煮，而瓜爾膠在冷水中就可以水化。化學組成上，刺槐豆膠平均每4個甘露糖單元才有1.5個乳糖支鏈。所以瓜爾膠分支單元數爲刺槐豆膠的2倍。而這被認爲是瓜爾膠比刺槐豆膠更容易水化和氫鍵結合活性更大的主要原因。除此之外，瓜爾膠的成本僅是刺槐豆膠的一半。
瓜爾膠直鏈上沒有非極性基團，大部分伯羥基和仲羥基都處在外側，而且半乳糖支鏈並沒有遮住活性的醇羥基。因而瓜爾膠具有最大的氫鍵結合面積，當與纖維結合時，形成的氫鍵結合距離短，結合力大。爲賦予瓜爾膠更好的使用性能，通常對瓜爾膠原粉進行化學改性。瓜爾膠的改性主要有兩個方向：一是在分子鏈上引入陽離子基團，從而穫得一定的正電性。如用季銨鹽3-氯2-羥丙基氯化銨與瓜爾膠原粉在有機溶劑中醚化反應生成陽離子瓜爾膠。這種帶正電的改性瓜爾膠便可以與帶負電的纖維、填料粒子相互作用從而提高原有的助留、助濾和增強效果。另一改性方向便是設法增加瓜爾膠分子鏈的長度，增大其分子量，從而增強其架橋連接能力。陽離子瓜爾膠在冷水中可溶，這與陽離子澱粉相比是一個很大優勢。
許多澱粉分子形成螺鏇狀結構，而瓜爾膠分子則形成直鏈結構。所以瓜爾膠的活性基團比陽離子澱粉更容易與纖維接近，從而少量的陽離子瓜爾膠便可能達到較多量陽離子澱粉才能達到的使用效果。當今，聚丙烯醯胺和改性澱粉廣泛應用於造紙中的助留助濾劑。但其效果隻能達到一定程度。它們在提高濾水的同時可能使纖維過度凝聚，從而降低紙頁勻度和強度。天然瓜爾膠作爲造紙助劑時，可以提高紙頁強度，減少灰斑形成並提高紙頁勻度。但它的缺點便是造成濾水困難，從而降低了產量或提高了幹燥部負荷。而經過化學改性的兩性或陽離子瓜爾膠則在很大程度上克服了這一弊病。實驗發現，這些改性的瓜爾膠能在提高紙頁濾水的同時保持或提高紙頁勻度；通過吸附細小纖維和粒子可以進一步改善濾水，同時提高一次留着率。而在過去，這兩方面都是互斥的。
由於陽離子瓜爾膠的有效性主要取決於它與纖維的親和性(即直接性)，所以它並不與“陰離子垃圾”反應。鑒於這一點，陽離子瓜爾膠在黑液的存在下仍能有效地發揮作用。對於新聞紙、未漂硫酸鹽漿、廢紙漿等含有較多雜質的漿料，隨着封閉水循環的推廣，陰離子垃圾的積累將顯著增加。這便會使得許多傳統的造紙助劑如陽離子聚丙烯醯胺(CPAM)等失去作用效果。陽離子瓜爾膠可以有效地克服這一點。實驗研究發現，陽離子瓜爾膠在Zeta電位從-8ｍV到0ｍV範圍内效果最好。該Zeta電位範圍與絕大部分造紙過程相吻合。
使用優點
1.在2合1香波配方中的表現使用配方完全一樣的2合1香波體系，包含有陽離子調理劑，硅油和相同的表面活性劑。香波中含有陽離子瓜爾膠及作爲比對的國内外常用同類調理劑A、B、C，結果顯示含陽離子瓜爾膠的體系性能和其它產品類似，不同的地方如下：在濕梳理和濕發感覺上，陽離子瓜爾膠優於A聚合物香波；在幹梳理方面，優於B聚合物香波；在濕梳理和泡沫量上，優於C聚合物香波。
2.陽離子瓜爾膠具有更少的積聚性和更好的親和能力 聚合物對頭髮的調理作用是在頭髮被沖洗時發生，被使用後頭髮具光澤，有回複自然的感覺。同沒有調理劑的一般香波比較，含有調理劑的香波往往會使幹發體積減少（頭髮緊貼頭皮，不蓬松），從原理上講，使用調理劑後幹發的梳理阻力減少得越多，頭髮的蓬松度越差，說明該聚合物有積聚行爲。試驗得知；陽離子瓜爾膠通過10次反複洗滌，仍然保持頭髮的豐盈程度，而不是越來越沉重，緊貼頭皮。說明該聚合物具有更少的積聚性。消除了長期使用後有積聚、沉重、發粘和頭髮枯萎的負面影響。
3.增加頭髮的光澤和健康 使用陽離子瓜爾膠聚合物的香波體系，能增加活性成分硅油和ZPT在頭髮上的停留，使頭髮呈現光彩和健康，保持易梳理、光亮和無靜電特征。
4.提高配方的穩定性 由於陽離子瓜爾膠具有懸浮、乳化的功能，當配方中硅油含量較高時，能起到懸浮和擕帶的作用，幫助在香波配方中穩定硅油。
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