[發明所欲解決之問題] 如上所述，先前之濃稠流質食品之大多數為1～2 kcal/mL之高能量型，且多為pH7附近之中性型，故而因其濃稠性導致後味之不佳成為問題。又，於專利文獻1、及專利文獻2中所揭示之酸性型濃稠流質食品中，來自乳肽及/或膠原蛋白肽之獨特之苦味(蛋白質分解臭味)之產生、及該酸性型濃稠流質食品本身之滲透壓之上升成為問題。 為了解決所述問題，只要可提供一種含有乳肽及/或膠原蛋白肽以外之蛋白質原料例如酪蛋白等乳蛋白原料之酸性型液狀營養組合物即可。另一方面，例如已知酪蛋白中在pH4.6周邊有等電點。若將酪蛋白應用於酸性型液狀營養組合物中，則由於蛋白質之凝聚，導致液狀營養組合物發生分離或沈澱。又，為了獲得乳化穩定性，專利文獻3中揭示有關於包含單甘油有機酸酯或聚甘油脂肪酸酯之酸性型濃稠流質食品之技術。單甘油有機酸酯或聚甘油脂肪酸酯為了獲得充分之乳化穩定性而必須以0.1～2.0重量%左右之濃度含有。於該情形時，因單甘油有機酸酯或聚甘油脂肪酸酯，導致風味降低。 本發明之課題在於開發一種以高濃度含有乳肽及/或膠原蛋白肽以外之蛋白質原料例如乳蛋白原料，風味良好，且乳化穩定性較高(不易發生分離或沈澱)之酸性液狀營養組合物。 [解決問題之技術手段] 本發明者等人鑒於上述先前之問題方面而進行努力研究，結果發現含有包含90質量%以上之乳清蛋白之蛋白質、脂質、糖質、膳食纖維、及0.01～2.0質量%之果膠的酸性液狀營養組合物其風味良好，且乳化穩定性較高(不易發生分離或沈澱)，從而完成本發明。 先前，於在酸性條件下使包含酪蛋白之豐富之乳蛋白的液狀營養組合物穩定之情形時，使用高甲氧基果膠(HM果膠)。藉由HM果膠之電荷之排斥作用，防止液狀營養組合物之分離或沈澱。本發明係乳清蛋白占蛋白質之90質量%以上之酸性型液狀營養組合物。 於本發明中，儘管酪蛋白幾乎不存在，但仍可使用HM果膠提高乳化穩定性。這令人震驚。本發明之酸性型液狀營養組合物由於不使用乳肽等肽原料，故而可避免來自肽原料之風味之惡化。 本發明之酸性液狀營養組合物由於乳化穩定性較高，且即便供於長時間保管亦抑制分離或沈澱，故而亦能夠長達數月地長時間保存。又，本發明之酸性液狀營養組合物可製成高蛋白質型，從而可獲得為高濃度高卡路里、穩定且風味良好之組合物。 即，本發明係提供以下[1]～[12]者。 [1]一種酸性液狀營養組合物，其含有：包含90質量%以上之乳清蛋白之蛋白質、脂質、糖質、膳食纖維、及0.01～2.0質量%之果膠。 [2]如[1]中所記載之酸性液狀營養組合物，其中上述乳清蛋白未經水解。 [3]如[2]中所記載之酸性液狀營養組合物，其中上述乳清蛋白選自由乳清蛋白濃縮物、乳清蛋白微胞、乳清蛋白分離物所組成之群中。 [4]如[1]至[3]中任一項所記載之酸性液狀營養組合物，其中上述酸性液狀營養組合物經加熱。 [5]如[1]至[4]中任一項所記載之酸性液狀營養組合物，其中pH為3～5。 [6]如[1]至[5]中任一項所記載之酸性液狀營養組合物，其中上述果膠為酯化度70%以上之高甲氧基果膠。 [7]如[1]至[6]中任一項所記載之酸性液狀營養組合物，其中上述蛋白質之含量為0.5～20 g/100 mL。 [8]如[1]至[7]中任一項所記載之酸性液狀營養組合物，其中能量含量為1～10 kcal/mL。 [9]如[1]至[8]中任一項所記載之酸性液狀營養組合物，其中上述蛋白質中之肽含量實質上為0質量%。 [10]如[1]至[9]中任一項所記載之酸性液狀營養組合物，其中上述蛋白質中之酪蛋白含量實質上為0質量%。 [11]如[1]至[10]中任一項所記載之酸性液狀營養組合物，其含有實質上為0質量%以上且未達0.1質量%之單甘油有機酸酯或聚甘油脂肪酸酯。 [12]如[1]至[11]中任一項所記載之酸性液狀營養組合物，其中單甘油有機酸酯及聚甘油脂肪酸酯之含量實質上為0質量%。 [發明之效果] 本發明係一種酸性液狀營養組合物，其含有：包含90質量%以上之乳清蛋白之蛋白質、脂質、糖質、維生素、礦物質、膳食纖維、及0.01～2.0質量%之果膠。[Problems to be Solved by the Invention] As mentioned above, most of the previous thick liquid foods were high energy types of 1 to 2 kcal / mL, and most of them were neutral types near pH 7, so their thickness caused Poor aftertaste becomes a problem. Furthermore, in the acidic thick liquid foods disclosed in Patent Documents 1 and 2, the unique bitterness (proteolytic odor) derived from milk peptides and / or collagen peptides is generated, and the acidic rich The increase in the osmotic pressure of the thick liquid food itself becomes a problem. In order to solve the problem, an acidic liquid nutrition composition containing a protein material other than milk peptide and / or collagen peptide, such as a milk protein material such as casein, may be provided. On the other hand, for example, it is known that casein has an isoelectric point around pH4.6. When casein is used in an acidic liquid nutrition composition, the liquid nutrition composition is separated or precipitated due to the aggregation of the protein. In addition, in order to obtain emulsion stability, Patent Document 3 discloses a technique for an acidic thick liquid food containing a monoglycerol organic acid ester or a polyglycerol fatty acid ester. The monoglycerol organic acid ester or polyglycerol fatty acid ester must be contained at a concentration of about 0.1 to 2.0% by weight in order to obtain sufficient emulsification stability. In this case, the monoglycerol organic acid ester or polyglycerol fatty acid ester causes a decrease in flavor. The object of the present invention is to develop an acidic liquid nutrition combination containing protein ingredients other than milk peptides and / or collagen peptides at high concentrations, such as milk protein raw materials, with good flavor and high emulsification stability (not easily separated or precipitated). Thing. [Technical means to solve the problem] The inventors of the present invention conducted diligent research in view of the foregoing problems, and found that the protein, lipid, sugar, dietary fiber, and 0.01 to 2.0 containing 90% by mass or more of whey protein were found. The pectin-based acidic liquid nutritional composition has a good flavor and high emulsification stability (not easy to separate or precipitate), thereby completing the present invention. Previously, in the case of stabilizing a liquid nutritional composition containing casein-rich milk protein under acidic conditions, high methoxy pectin (HM pectin) was used. By the repulsive effect of the charge of HM pectin, the separation or precipitation of the liquid nutritional composition is prevented. The present invention is an acidic liquid nutrition composition in which whey protein accounts for more than 90% by mass of protein. In the present invention, although casein is almost absent, HM pectin can still be used to improve emulsion stability. This is shocking. Since the acidic liquid nutrition composition of the present invention does not use peptide raw materials such as milk peptides, it is possible to avoid deterioration of the flavor derived from the peptide raw materials. The acidic liquid nutritional composition of the present invention has high emulsification stability and suppresses separation or precipitation even when it is stored for a long time, so it can be stored for a long time for several months. In addition, the acidic liquid nutritional composition of the present invention can be made into a high-protein type, so that a high-concentration, high-calorie, stable, and good-flavored composition can be obtained. That is, the present invention provides the following [1] to [12]. [1] An acidic liquid nutritional composition comprising a protein, lipid, saccharide, dietary fiber, and 0.01 to 2.0% by mass of pectin, which contains 90% by mass or more of whey protein. [2] The acidic liquid nutritional composition according to [1], wherein the whey protein is not hydrolyzed. [3] The acidic liquid nutritional composition according to [2], wherein the whey protein is selected from the group consisting of a whey protein concentrate, a whey protein cell, and a whey protein isolate. [4] The acidic liquid nutritional composition according to any one of [1] to [3], wherein the acidic liquid nutritional composition is heated. [5] The acidic liquid nutritional composition according to any one of [1] to [4], wherein the pH is 3 to 5. [6] The acidic liquid nutritional composition according to any one of [1] to [5], wherein the pectin is a high methoxyl pectin having an esterification degree of 70% or more. [7] The acidic liquid nutritional composition according to any one of [1] to [6], wherein the content of the protein is 0.5 to 20 g / 100 mL. [8] The acidic liquid nutritional composition according to any one of [1] to [7], wherein the energy content is 1 to 10 kcal / mL. [9] The acidic liquid nutritional composition according to any one of [1] to [8], wherein the peptide content in the protein is substantially 0% by mass. [10] The acidic liquid nutritional composition according to any one of [1] to [9], wherein the casein content in the protein is substantially 0% by mass. [11] The acidic liquid nutritional composition according to any one of [1] to [10], which contains substantially 0% by mass or more and less than 0.1% by mass of a monoglyceryl organic acid ester or a polyglycerol fat Acid ester. [12] The acidic liquid nutritional composition according to any one of [1] to [11], wherein the content of the monoglycerol organic acid ester and the polyglycerol fatty acid ester is substantially 0% by mass. [Effects of the Invention] The present invention is an acidic liquid nutritional composition containing protein, lipids, sugars, vitamins, minerals, dietary fiber, and 0.01-2.0% by mass containing whey protein of 90% by mass or more Of pectin.
以下，對本發明進行詳細說明，但本發明並不限於以下所述之各個形態。 本發明係一種酸性液狀營養組合物，其含有：包含90質量%以上之乳清蛋白之蛋白質、脂質、糖質、膳食纖維、及0.01～2.0質量%之果膠。 蛋白質只要包含乳清蛋白，則其種類、及精製度等並無限制。乳清蛋白可使用包含乳清蛋白之原料：例如乳清粉、乳清蛋白濃縮物(WPC(Whey protein concentrate，乳清濃縮蛋白)、WPI(Whey protein isolate，乳清分離蛋白))、乳清、乳清蛋白微胞、乳清蛋白濃縮物。乳清蛋白較佳為未經水解者。即，於本發明之酸性液狀營養組合物中，較佳為不含肽。本發明之酸性液狀營養組合物中亦幾乎不含酪蛋白。只要為無損本發明之效果之量，則亦可包含肽及酪蛋白等。 本發明之酸性液狀營養組合物中之乳清蛋白之含量較佳為0.5～20質量%。乳清蛋白之含量更佳為1～15質量%，進而較佳為2～12質量%，進而更佳為3～10質量%，特佳為5～10質量%。藉由將乳清蛋白之含量設為0.5質量%以上，可實現本發明之效果。又，藉由將乳清蛋白之含量設為20質量%以下，而提高乳化穩定性。即，抑制酸性液狀營養組合物之分離或沈澱。 本發明之酸性液狀營養組合物中之蛋白質整體之90質量%以上為乳清蛋白。若乳清蛋白占蛋白質整體之90質量%以上，則可實現本發明之效果。乳清蛋白之含量較佳為蛋白質整體之92質量%以上，更佳為94質量%以上，進而更佳為96質量%以上，最佳為98質量%以上。 本發明之酸性液狀營養組合物可應用於高濃度型即濃稠型之流質食品。例如，蛋白質含量較佳為0.5～20 g/100 mL。蛋白質含量更佳為1～15 g/100 mL，進而較佳為2～12 g/100 mL，進而更佳為3～10 g/100 mL，特佳為5～10 g/100 mL。又，例如酸性液狀營養組合物之能量含量較佳為1～10 kcal/mL，更佳為1～5 kcal/mL，進而較佳為1～3 kcal/mL，特佳為1～2 kcal/mL。 脂質可使用公知之脂質原料，其種類、及精製度等並無限制。脂質原料可使用市售之食用油脂等，例如動物油脂、植物油脂、魚油等。 本發明之酸性液狀營養組合物中之脂質之含量較佳為0.5～10質量%，更佳為1～8質量%，進而更佳為2～6質量%，特佳為3～5質量%。藉由將脂質之含量設為0.5質量%以上，本發明之酸性液狀營養組合物之營養價值增高。若脂質之含量為10質量%以下，則可避免本發明之酸性液狀營養組合物之風味之降低。 糖質可使用公知之糖質原料，其種類、及精製度等無限制。糖質原料可使用市售之糖質原料等，例如單糖類、二糖類等寡糖類，澱粉、糊精等。 本發明之酸性液狀營養組合物中之糖質之含量較佳為5～50質量%，更佳為10～40質量%，進而更佳為15～30質量%，特佳為15～25質量%。藉由將糖質之含量設為5質量%以上，本發明之酸性液狀營養組合物之營養價值增高。若糖質之含量為50質量%以下，則可避免本發明之酸性液狀營養組合物之風味之降低。 膳食纖維可使用公知之膳食纖維，其種類、及精製度等並無限制。膳食纖維原料可使用市售之原料等，例如難消化性糊精、葡聚糖等水溶性膳食纖維。 本發明之酸性液狀營養組合物中之膳食纖維之含量較佳為0.1～20質量%，更佳為0.2～10質量%，進而更佳為0.3～5質量%，特佳為0.4～1質量%。藉由將膳食纖維之含量設為0.1質量%以上，本發明之酸性液狀營養組合物之營養價值提高。又，藉由將膳食纖維之含量設為20質量%以下，可享受來自膳食纖維之功能性。 於本發明之酸性液狀營養組合物中，含有果膠作為穩定劑之至少一部分。果膠可使用公知之果膠原料，尤其較佳為酯化度70%以上之高甲氧基果膠(HM果膠)。又，與HM果膠同樣地有電荷之排斥作用之原料例如大豆多糖類、羧甲基纖維素、海藻酸鈉等，可作為果膠之代替品而使用。只要為無損本發明之效果之量，則亦可包含單甘油有機酸酯或聚甘油脂肪酸酯等。 本發明之酸性液狀營養組合物中之果膠之含量可設為0.01～20質量%。果膠之含量較佳為0.02～10質量%，更佳為0.03～5質量%，最佳為0.01～2.0質量%。果膠之含量亦可設為0.05～1質量%。藉由將果膠之含量設為0.01質量%以上，可實現本發明之效果。又，藉由將果膠之含量設為2.0質量%以下，本發明之酸性液狀營養組合物成為容易飲用之形態。 本發明之酸性液狀營養組合物若為已加熱處理者，就保存或流通之觀點而言較佳。加熱處理可於與公知之可常溫流通之流質食品或營養食品相同的條件下進行。加熱處理例如可設為在110～150℃且1～60秒鐘下之UHT(Ultra High Temperature，超高溫)殺菌。加熱條件較佳為120～150℃且1～30秒鐘，更佳為120～145℃且1～30秒鐘。 本發明之酸性液狀營養組合物由於為酸性，故而風味清爽而容易攝入。本發明之酸性液狀營養組合物之pH較佳為3～5，更佳為3.5～4.5，最佳為3.8～4.2。 於本發明之酸性液狀營養組合物中，可任意添加維生素、礦物質等公知之食品原料或食品添加物。 作為本發明之酸性液狀營養組合物之形態，可列舉「流質食品」。「流質食品」為應用於經口、經管地投予之食品組合物，主要是對胃腸系疾病之患者或高齡者等有效地補充營養。「流質食品」尤其多用於住院患者中之術前、術後之營養管理。此種流質食品必須為高濃度、且高卡路里。進而，「流質食品」較佳為消化吸收亦良好，且平衡性良好地調配蛋白質、脂質、糖質之3大營養元素與維生素類、礦物質類。 再者，本發明之酸性液狀營養組合物較佳為具有作為流質食品之普通黏度(3～500 mPa・s(20℃))。本發明之酸性液狀營養組合物之黏度更佳為5～100 mPa・s(20℃)，進而較佳為7～75 mPa・s(20℃)，特佳為20～50 mPa・s(20℃)。 [實施例] 以下，列舉實施例對本發明進行進一步詳細說明，但本發明並不受其限定。再者，於實施例中，「%」標識除特殊說明之情形外，表示質量%。 [試驗例] 向1600 mL之溫水(60℃)中添加未經水解處理之乳清蛋白濃縮物226.5 g、粉末糊精(松谷化學公司之TK-16)726 g、植物性油脂121.5 g、難消化性糊精(松谷化學公司之Pine fiber C)27 g、礦物質混合物(含檸檬酸)62.2 g、維生素混合物2.3 g、香料0.3 g。以相同之組成製備6種。分別以成為特定之濃度之方式加入作為穩定劑之HM果膠(CP Kelco公司之YM115-LJ，酯化度72%)，從而獲得組合物原料。 利用TK均質攪拌機(TK homomixer)(特殊機化工業股份有限公司製造)將各組合物原料預乳化後，添加水將總量製備成3000 mL。該等6種預乳化物中之各成分之組成如表1所示。HM果膠之濃度設為0%(試驗例1)、0.5%(試驗例2)、0.6%(試驗例3)、0.8%(試驗例4)、1.0%(試驗例5)、1.2%(試驗例6)。 [表1]
對於試驗例1～6之預乳化物，利用高壓均質機(GEA Process Engineering股份有限公司製造)實施2階段均質化處理。2階段均質化處理中之每單位面積之質量設為第一階段50 kg/cm2
、第二階段200 kg/cm2
。進行該2階段均質化處理共計2次，經過125℃且5秒鐘之加熱殺菌，從而獲得試驗例1～6之酸性液狀營養組合物。 試驗例1～6之酸性液狀營養組合物之pH為4.0。試驗例1～6之酸性液狀營養組合物其能量含量為1.6 kcal/mL，蛋白質濃度為6 g/100 mL。試驗例1～6之酸性液狀營養組合物其蛋白質之100質量%為乳清蛋白。肽及酪蛋白未包含於試驗例1～6之酸性液狀營養組合物中。而且，試驗例1～6之酸性液狀營養組合物由於含有HM果膠作為穩定劑，故而風味良好。 將試驗例1～6之酸性液狀營養組合物於40℃下保存2週時間。其結果為，於作為穩定劑之HM果膠之添加量為0%之試驗例1中，發生分離、離水。相對於此，於含有0.5～1.2%之HM果膠之試驗例2～6中，未發生分離、離水。 [表2]
[實施例1] 向26000 mL之溫水(60℃)中添加乳清蛋白濃縮物4500 g、HM果膠90 g、液體糊精16200 g、蔗糖600 g、植物性油脂2340 g、難消化性糊精940 g、礦物質混合物1850 g、維生素混合物53 g、香料415 g，並利用均質攪拌機進行預乳化。向所獲得之預乳化物中添加水，將總量製備成60000 mL。 對於預乳化物，實施2次利用高壓均質機之2階段均質化處理。第1次處理中之每單位面積之質量設為第一階段50 kg/cm2
、第二階段300 kg/cm2
。第2次處理中之每單位面積之質量設為第一階段50 kg/cm2
、第二階段200 kg/cm2
。進而，進行125℃且5秒鐘之加熱殺菌，從而獲得實施例1之酸性液狀營養組合物。 實施例1之酸性液狀營養組合物之pH為4.0。實施例1之酸性液狀營養組合物其能量含量為1.6 kcal/mL，蛋白質濃度為6 g/100 mL(其中，蛋白質中之乳清蛋白之比率為100%)，黏度為25 mPa・s(20℃)。 實施例1之酸性液狀營養組合物其過喉感良好，為良好之風味。將該酸性液狀營養組合物於25℃下保存，於8個月後開封。於開封之酸性液狀營養組合物中，未發生分離或沈澱。 [產業上之可利用性] 本發明可提供一種風味良好、物性穩定，乳化穩定性較高(不易發生分離或沈澱)，且可長期保存之酸性液狀營養組合物。Hereinafter, the present invention is described in detail, but the present invention is not limited to each aspect described below. The present invention is an acidic liquid nutrition composition, which contains: protein, lipid, saccharide, dietary fiber, and 0.01 to 2.0% by mass of pectin, which contains 90% by mass or more of whey protein. As long as the protein includes whey protein, there is no limitation on the type, the refined system, and the like. For whey protein, raw materials including whey protein can be used: for example, whey powder, whey protein concentrate (WPC (Whey protein concentrate), WPI (Whey protein isolate, whey protein isolate)), whey , Whey protein cells, whey protein concentrate. Whey protein is preferably one without hydrolysis. That is, it is preferable that the acidic liquid nutritional composition of this invention does not contain a peptide. The acidic liquid nutritional composition of the present invention also contains almost no casein. As long as the effect of the present invention is not impaired, peptides, casein, and the like may be included. The content of whey protein in the acidic liquid nutrition composition of the present invention is preferably 0.5 to 20% by mass. The content of whey protein is more preferably 1 to 15% by mass, still more preferably 2 to 12% by mass, still more preferably 3 to 10% by mass, and particularly preferably 5 to 10% by mass. The effect of the present invention can be achieved by setting the content of whey protein to 0.5% by mass or more. Moreover, emulsification stability is improved by setting the content of whey protein to 20% by mass or less. That is, the separation or precipitation of the acidic liquid nutrition composition is suppressed. 90% by mass or more of the entire protein in the acidic liquid nutritional composition of the present invention is whey protein. If the whey protein accounts for more than 90% by mass of the entire protein, the effect of the present invention can be achieved. The content of whey protein is preferably 92% by mass or more, more preferably 94% by mass or more, still more preferably 96% by mass or more, and most preferably 98% by mass or more. The acidic liquid nutrition composition of the present invention can be applied to high-concentration type, that is, thick liquid food. For example, the protein content is preferably 0.5 to 20 g / 100 mL. The protein content is more preferably 1 to 15 g / 100 mL, more preferably 2 to 12 g / 100 mL, still more preferably 3 to 10 g / 100 mL, and particularly preferably 5 to 10 g / 100 mL. For example, the energy content of the acidic liquid nutrition composition is preferably 1 to 10 kcal / mL, more preferably 1 to 5 kcal / mL, even more preferably 1 to 3 kcal / mL, and particularly preferably 1 to 2 kcal. / mL. As the lipid, well-known lipid materials can be used, and there are no restrictions on the type and the precise system. As the lipid raw material, commercially available edible oils and fats, such as animal fats, vegetable fats, and fish oils, can be used. The lipid content in the acidic liquid nutrition composition of the present invention is preferably 0.5 to 10% by mass, more preferably 1 to 8% by mass, even more preferably 2 to 6% by mass, and particularly preferably 3 to 5% by mass. . By setting the lipid content to 0.5% by mass or more, the nutritional value of the acidic liquid nutrition composition of the present invention is increased. When the content of the lipid is 10% by mass or less, the flavor of the acidic liquid nutritional composition of the present invention can be prevented from decreasing. As the saccharide, a known saccharide material can be used, and there are no restrictions on its type and refinement system. As the sugar material, commercially available sugar materials can be used, such as oligosaccharides such as monosaccharides and disaccharides, starch, dextrin, and the like. The content of the saccharide in the acidic liquid nutrition composition of the present invention is preferably 5 to 50% by mass, more preferably 10 to 40% by mass, even more preferably 15 to 30% by mass, and particularly preferably 15 to 25% by mass. %. By setting the content of saccharides to 5 mass% or more, the nutritional value of the acidic liquid nutrition composition of the present invention is increased. When the content of the saccharide is 50% by mass or less, the flavor of the acidic liquid nutritional composition of the present invention can be prevented from decreasing. As the dietary fiber, a well-known dietary fiber can be used, and there are no restrictions on the type and the refined system. As the dietary fiber raw material, commercially available raw materials can be used, for example, water-soluble dietary fiber such as indigestible dextrin and dextran. The content of dietary fiber in the acidic liquid nutrition composition of the present invention is preferably 0.1 to 20% by mass, more preferably 0.2 to 10% by mass, even more preferably 0.3 to 5% by mass, and particularly preferably 0.4 to 1% by mass. %. By setting the content of dietary fiber to 0.1% by mass or more, the nutritional value of the acidic liquid nutrition composition of the present invention is improved. In addition, by setting the content of dietary fiber to 20% by mass or less, the functionality derived from dietary fiber can be enjoyed. The acidic liquid nutritional composition of the present invention contains pectin as at least a part of the stabilizer. As the pectin, a well-known pectin raw material can be used, and high methoxy pectin (HM pectin) having an esterification degree of 70% or more is particularly preferable. In addition, raw materials having a charge-repellent effect similar to HM pectin, such as soybean polysaccharides, carboxymethyl cellulose, and sodium alginate, can be used as substitutes for pectin. As long as it is the amount which does not impair the effect of this invention, it may contain monoglycerol organic acid ester, polyglycerol fatty acid ester, etc. The content of pectin in the acidic liquid nutritional composition of the present invention may be set to 0.01 to 20% by mass. The content of pectin is preferably 0.02 to 10% by mass, more preferably 0.03 to 5% by mass, and most preferably 0.01 to 2.0% by mass. The content of pectin can also be set to 0.05 to 1% by mass. The effect of the present invention can be achieved by setting the content of pectin to 0.01% by mass or more. In addition, by setting the content of pectin to 2.0% by mass or less, the acidic liquid nutritional composition of the present invention is in a form easy to drink. The acidic liquid nutritional composition of the present invention is preferably heat-treated, from the viewpoint of storage or distribution. The heat treatment can be performed under the same conditions as the liquid foods or nutritional foods which are known to circulate at normal temperature. The heat treatment may be, for example, UHT (Ultra High Temperature) sterilization at 110 to 150 ° C. for 1 to 60 seconds. The heating conditions are preferably 120 to 150 ° C and 1 to 30 seconds, and more preferably 120 to 145 ° C and 1 to 30 seconds. Since the acidic liquid nutrition composition of the present invention is acidic, the flavor is refreshing and easy to take in. The pH of the acidic liquid nutritional composition of the present invention is preferably 3 to 5, more preferably 3.5 to 4.5, and most preferably 3.8 to 4.2. In the acidic liquid nutrition composition of the present invention, known food materials or food additives such as vitamins and minerals can be arbitrarily added. As a form of the acidic liquid nutrition composition of this invention, "liquid food" is mentioned. "Liquid food" is a food composition used for oral and management administration, and is mainly used to effectively supplement nutrition for patients with gastrointestinal diseases or the elderly. "Liquid food" is especially used for nutrition management before and after surgery in hospitalized patients. This liquid food must be high in concentration and high in calories. Furthermore, the "liquid food" is preferably one that has good digestion and absorption, and is well-balanced with the three major nutrients of proteins, lipids and sugars, vitamins and minerals. The acidic liquid nutritional composition of the present invention preferably has an ordinary viscosity (3 to 500 mPa · s (20 ° C)) as a liquid food. The viscosity of the acidic liquid nutritional composition of the present invention is more preferably 5 to 100 mPa · s (20 ° C), more preferably 7 to 75 mPa · s (20 ° C), and particularly preferably 20 to 50 mPa · s ( 20 ° C). [Examples] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. Furthermore, in the embodiment, the "%" mark indicates the mass% unless otherwise specified. [Test Example] To 1600 mL of warm water (60 ° C), 226.5 g of whey protein concentrate without hydrolysis treatment, 726 g of powder dextrin (TK-16 of Matsushita Chemical Co., Ltd.), 121.5 g of vegetable oils and fats, Indigestible dextrin (Pine fiber C from Matsugu Chemical Co.) 27 g, mineral mixture (including citric acid) 62.2 g, vitamin mixture 2.3 g, and flavor 0.3 g. Six kinds were prepared with the same composition. HM pectin (YM115-LJ of CP Kelco Company, degree of esterification 72%) was added as a specific concentration to obtain a raw material for the composition. Each composition raw material was pre-emulsified with a TK homomixer (manufactured by Special Machinery Co., Ltd.), and water was added to prepare a total amount of 3000 mL. The composition of each component in these 6 kinds of pre-emulsification is shown in Table 1. The concentration of HM pectin was set to 0% (Test Example 1), 0.5% (Test Example 2), 0.6% (Test Example 3), 0.8% (Test Example 4), 1.0% (Test Example 5), 1.2% ( Test example 6). [Table 1] The pre-emulsified products of Test Examples 1 to 6 were subjected to a two-stage homogenization process using a high-pressure homogenizer (manufactured by GEA Process Engineering Co., Ltd.). The mass per unit area in the two-stage homogenization process was set to 50 kg / cm 2 in the first stage and 200 kg / cm 2 in the second stage. This two-stage homogenization treatment was performed a total of two times, and heat sterilization was performed at 125 ° C. for 5 seconds to obtain the acidic liquid nutritional composition of Test Examples 1 to 6. The pH of the acidic liquid nutrition composition of Test Examples 1 to 6 was 4.0. The acidic liquid nutrition composition of Test Examples 1 to 6 had an energy content of 1.6 kcal / mL and a protein concentration of 6 g / 100 mL. 100% by mass of the protein in the acidic liquid nutrition composition of Test Examples 1 to 6 was whey protein. The peptide and casein were not included in the acidic liquid nutritional composition of Test Examples 1 to 6. In addition, the acidic liquid nutritional compositions of Test Examples 1 to 6 had good flavor because they contained HM pectin as a stabilizer. The acidic liquid nutritional compositions of Test Examples 1 to 6 were stored at 40 ° C for two weeks. As a result, in Test Example 1 in which the addition amount of HM pectin as a stabilizer was 0%, separation and dehydration occurred. In contrast, in Test Examples 2 to 6 containing 0.5 to 1.2% of HM pectin, no separation or water separation occurred. [Table 2] [Example 1] To 26000 mL of warm water (60 ° C), 4500 g of whey protein concentrate, 90 g of HM pectin, 16200 g of liquid dextrin, 600 g of sucrose, 2340 g of vegetable oil, and indigestibility were added. 940 g of dextrin, 1850 g of mineral mixture, 53 g of vitamin mixture, and 415 g of flavor were pre-emulsified with a homomixer. Water was added to the obtained pre-emulsion to prepare a total amount of 60,000 mL. The pre-emulsified product was subjected to a two-stage homogenization treatment using a high-pressure homogenizer twice. The mass per unit area in the first treatment was set to 50 kg / cm 2 in the first stage and 300 kg / cm 2 in the second stage. The mass per unit area in the second treatment was set to 50 kg / cm 2 in the first stage and 200 kg / cm 2 in the second stage. Furthermore, heat sterilization was performed at 125 ° C. for 5 seconds to obtain the acidic liquid nutrition composition of Example 1. The pH of the acidic liquid nutritional composition of Example 1 was 4.0. The acidic liquid nutritional composition of Example 1 had an energy content of 1.6 kcal / mL, a protein concentration of 6 g / 100 mL (wherein the ratio of whey protein in the protein was 100%), and a viscosity of 25 mPa · s ( 20 ° C). The acidic liquid nutritional composition of Example 1 had a good throat feeling and was a good flavor. The acidic liquid nutritional composition was stored at 25 ° C, and opened after 8 months. In the Kaifeng acidic liquid nutritional composition, no separation or precipitation occurred. [Industrial Applicability] The present invention can provide an acidic liquid nutrition composition with good flavor, stable physical properties, high emulsion stability (not easy to separate or precipitate), and long-term storage.