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刘容旭，李春雨，王语聪，等. 超高压辅助酶解法改性汉麻分离蛋白及其理化性质的研究[J]. 食品工业科技，2023，44（19）：99−107.doi: 10.13386/j.issn1002-0306.2023010016LIU Rongxu, LI Chunyu, WANG Yucong, et al. Study on the Modification and Physicochemical Properties of Hemp Protein Isolate by Ultra-High Pressure Assisted Enzymatic Hydrolysis[J]. Science and Technology of Food Industry, 2023, 44(19): 99−107. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2023010016· 研究与探讨 ·超高压辅助酶解法改性汉麻分离蛋白及其理化性质的研究刘容旭1，李春雨2，王语聪2，谢智鑫2，谢宜桐2，李双鹏2，刘丹怡1, *，韩建春2,*（1.黑龙江省绿色食品科学研究院，黑龙江哈尔滨 150028；2.东北农业大学 食品学院，黑龙江哈尔滨 150030）摘 要：本研究以汉麻分离蛋白（Hemp Protein Isolate ，HPI ）为原料，通过超高压辅助酶解反应对HPI 进行改性，以溶解度和水解度为判定指标筛选酶解改性反应最佳条件，并探究超高压辅助酶解反应对酶解产物溶解性、起泡性、乳化性、持水性、持油性的影响。
结果表明，HPI 酶解反应最适条件为：加酶量（复合蛋白酶）5000 U/g 、酶解改性pH8.0、酶解改性温度55 ℃、酶解改性时间50 min 。
以HPI 为对照，当压力为200 MPa 时，酶解产物的溶解度、起泡性、乳化性、持油性最高，压力为100 MPa 时，泡沫稳定性最好，酶解后的乳化稳定性存在不同程度的下降，压力为0.1 MPa 时其持水性达到最大值。
李安林，王琳，许程剑，等. 基于主成分分析和响应曲面法的烤肉腌制剂配方优化[J]. 食品工业科技，2023，44（10）：195−202. doi:10.13386/j.issn1002-0306.2022080015LI Anlin, WANG Lin, XU Chengjian, et al. Optimization of Roasted Pork Curing Agent Formulation Based on Principal Component Analysis and Response Surface Methodology[J]. Science and Technology of Food Industry, 2023, 44(10): 195−202. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2022080015· 工艺技术 ·基于主成分分析和响应曲面法的烤肉腌制剂配方优化李安林1，王 琳2，许程剑3，周 宇3，熊双丽3, *（1.四川旅游学院图书馆，四川成都 610100；2.西南科技大学生命科学与工程学院，四川绵阳 621010；3.四川旅游学院食品学院，四川成都 610100）摘 要：论文以猪里脊肉为原料，考察茶多酚、大豆分离蛋白和大蒜对烤肉品质的影响。
以感官评分、色泽、丙二醛含量和过氧化值为响应指标，通过进行单因素、主成分分析及Box-Benhnken 响应曲面设计优化烤制猪肉腌制剂配方。
结果表明，单因素实验中茶多酚对烤肉感官评分影响不显著。
感官评分随大豆分离蛋白、大蒜和菜籽油添加量的加大，皆呈先升高后降低趋势，在三者分别为2%、5%和12%时最高。
大豆分离蛋白和茶多酚抑制脂肪氧化效果优于大蒜和菜籽油，茶多酚和菜籽油能较好提升烤肉L *值。
主成分分析及Box-Benhnken 响应曲面设计优化结果显示，各添加剂最佳添加量分别为大蒜4.8%、大豆分离蛋白2.0%、菜籽油12.0%，茶多酚0.03%，得到规范化综合评分0.95，与预测值0.98基本一致。
文伟，胡淼，侯丽真，等. 大豆乳清蛋白特性及回收利用研究进展[J]. 食品工业科技，2023，44（9）：413−421. doi:10.13386/j.issn1002-0306.2022060059WEN Wei, HU Miao, HOU Lizhen, et al. Research Progress on Characteristics and Recycling of Soybean Whey Proteins[J]. Science and Technology of Food Industry, 2023, 44(9): 413−421. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2022060059· 专题综述 ·大豆乳清蛋白特性及回收利用研究进展文 伟，胡 淼，侯丽真，高雅鑫，田志良，李丹枫，范 蓓，王凤忠*，李淑英*（中国农业科学院农产品加工研究所，北京 100193）摘 要：大豆分离蛋白加工过程中产生大量乳清废水，直接排放会造成环境污染和资源浪费。
大豆乳清废水中含有大豆乳清蛋白（Soybean Whey Proteins, SWP ）、大豆异黄酮、大豆低聚糖等多种营养成分，其中大豆乳清蛋白应用价值极高，富含胰蛋白酶抑制剂、β-淀粉酶、大豆血球凝集素、脂肪氧合酶等多种功能因子。
基于此，本文针对大豆乳清蛋白的回收利用，归纳总结了大豆乳清蛋白中的主要组成成分，并对各组分的研究利用以及其功能特性进行总结与分析，同时对大豆乳清蛋白的回收方法及利用进行了梳理，以期为工业生产实践中高值化利用提供理论和技术上的参考。
关键词：大豆乳清蛋白，组分成分，理化性质，分离提取，食品应用本文网刊:中图分类号：TS201 文献标识码：A 文章编号：1002−0306（2023）09−0413−09DOI: 10.13386/j.issn1002-0306.2022060059Research Progress on Characteristics and Recycling ofSoybean Whey ProteinsWEN Wei ，HU Miao ，HOU Lizhen ，GAO Yaxin ，TIAN Zhiliang ，LI Danfeng ，FAN Bei ，WANG Fengzhong *，LI Shuying *（Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing 100193, China ）Abstract ：Soybean protein isolate processing and production produces a large amount of soybean whey wastewater, which causes environmental pollution and waste of resources directly discharged. Soybean whey wastewater contains soybean whey proteins (SWP), soybean isoflavones, soybean oligosaccharides and other nutrients, of which soybean whey proteins application value is extremely high, rich in trypsin inhibitors, β-amylase, soybean hemagglutinin, lipoxygenase and other functional factors. Therefore, with regard to the recycling of soy whey proteins, this paper sumerizes the main components in soybean whey proteins, analyses functional properties and research purposes of each component, and sortes out the recovery methods and applications of soy whey proteins. The aim of this paper is to provide a theoretical and technical reference for high value utilisation in industrial production practice.Key words ：soybean whey proteins ；components ；physical and chemical properties ；separation and extraction ；food application大豆原产于中国，是一年生草本植物，是优质植物蛋白质、食用油脂和饲用蛋白的主要来源。
V o l.24,2017，N〇.6乂。
：=择粮食与食品工&Cereal and Fc^od Industry粮油工程大豆分离蛋白的功能特性及应用冯建岭1，彭云婷1，李迎秋21.威海市食品药品检验检测中心（威海 264210)2.齐鲁工业大学食品科学与工程学院（济南 250353)摘要：综述了大豆分离蛋白的功能特性及应用，并展望了大豆分离蛋白的发展前景，为未来大豆分离蛋白的研究趋势和新型大豆蛋白产品的开发提供一定的科学指导和理论依据。
关键词：大豆分离蛋白；功能特性；应用中图分类号：T S201 文献标识码：B文章编号：1672- 5026(2017)06-037-04Functional properties and applications of soy protein isolateF e n g Jianling1，P e n g Y u n t i n g1，Li Y i n g q i u21. Weihai Center for Food and Drug Inspection (Weihai 264210)2. College of Food Science & Engineering，Qilu University of Technology (Jinan 250353)Abstract：T h e functional properties a n d applications of soy protein isolate w e r e s h o w e d.F u rt h e r m o r e，the prospect of soy protein isolate w a s reviewed a n d substantial scientitic guidance a n d theoretical basis for the future research trends a n d exploitation of n e w products o late w e r e provided.Key words：soy protein isolate；functional properties；application大豆因其高营养价值及良好的功能特性而闻名，不仅是一种优良的油料作物，更是一种理想的食 用蛋白质资源，多不饱和脂肪酸和有益的生物活性物质含量丰富。
崔颂，张月，刘超然，等. 羧甲基纳米纤维素稳定的低油相Pickering 乳液凝胶的制备及性质分析[J]. 食品工业科技，2023，44（10）：70−77. doi: 10.13386/j.issn1002-0306.2022070180CUI Song, ZHANG Yue, LIU Chaoran, et al. Preparation and Property Analysis of Carboxymethyl Nanocellulose Stabilized Low Oil Phase Pickering Emulsion Gels[J]. Science and Technology of Food Industry, 2023, 44(10): 70−77. (in Chinese with English abstract).doi: 10.13386/j.issn1002-0306.2022070180· 研究与探讨 ·羧甲基纳米纤维素稳定的低油相Pickering乳液凝胶的制备及性质分析崔 颂，张 月，刘超然，王一凡，代 蕾*（青岛农业大学食品科学与工程学院，山东青岛 266109）摘 要：结合pH 对羧甲基纳米纤维素（CMCN ）的ζ-电位、接触角的影响，本文以CMCN 溶液为连续相，玉米油为分散相构建低油相（20%）Pickering 乳液凝胶，研究了CMCN 稳定的Pickering 乳液凝胶的类型、微观结构、流变学特性和不同条件下的稳定性。
结果表明：从pH2到pH9，CMCN 的ζ-电位从−2 mV 减小到−67 mV ，其中在pH4时ζ-电位绝对值相对较大且具有最接近90°的接触角，因此pH4时的CMCN 更适合稳定低油相Pickering 乳液凝胶。
荧光显微镜和流变学结果分别证明CMCN 稳定的Pickering 乳液凝胶为O/W 型，且在低油浓度下形成了类弹性结构（G'>G''），为假塑性流体。
胡婷，韩嘉龙，耿勤，等. 动物蛋白与植物蛋白对甜菜苷的热保护作用机制研究[J]. 食品工业科技，2023，44（7）：10−18. doi:10.13386/j.issn1002-0306.2022090301HU Ting, HAN Jialong, GENG Qin, et al. Study of the Thermal Protection Mechanism of Animal Proteins and Plant Proteins on Betanin[J]. Science and Technology of Food Industry, 2023, 44(7): 10−18. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2022090301· 青年编委专栏—食品营养素包埋与递送（客座主编：黄强、蔡杰、陈帅） ·动物蛋白与植物蛋白对甜菜苷的热保护作用机制研究胡 婷1，韩嘉龙1，耿 勤1，陈 军1，李 俶1，刘成梅1，何雪梅2，戴涛涛1,2,*（1.南昌大学食品科学与技术国家重点实验室，江西南昌 330047；2.广西果蔬贮藏与加工新技术重点实验室，广西南宁 530007）摘 要：为探究不同蛋白质对甜菜苷的热保护作用，明晰其保护机制，本文拟采用两种动物蛋白（乳铁蛋白和β-乳球蛋白）、两种植物蛋白（大米蛋白和大豆分离蛋白）为原料，采用浊度、紫外光谱、粒径、分子模拟等手段表征蛋白-甜菜苷复合物的形成和相互作用机制。
结果表明，四种蛋白质均能提高甜菜苷的热稳定性，保护效果为：乳铁蛋白>大豆分离蛋白>β-乳球蛋白≈大米蛋白，蛋白质对甜菜苷热稳定性的提高与蛋白-甜菜苷复合物的形成有关。
通过浊度、紫外光谱、粒径的实验结果推测，甜菜苷与乳铁蛋白、β-乳球蛋白、大豆分离蛋白的结合程度高于大米蛋白，这可能是由于大米蛋白的低溶解度和紧密结构造成的。
第1期（总第520期) 2021年1月农产品加工Farm Products ProcessingNo.1Jan.文章编号：1671-9646 (2021)01b-0059-05大豆肽的功能活性及其在食品加工中的应用王露露，史茜茜，王雨桐，谷鑫，姜雨彤，**韩齐(黑龙江八一农垦大学食品学院，黑龙江大庆163319)摘要：大豆活性肽是大豆蛋白的水解产物，因具有多种功能活性而受到广泛关注，并且大豆活性肽的稳定性更好，加工性能也优于大豆蛋白。
综述了大豆肽的活性功能，如降血压、降血脂、抗疲劳和抗氧化等，并对其在不同种类 食品中的应用进行了分析和展望，为大豆活性肽在食品加工中的应用提供参考。
关键词：大豆肽；功能活性；食品加工；应用中图分类号：TS202.1 文献标志码： A doi：10.16693/ki.1671-9646(X).2021.01.050Function of Soybean Bioactive Peptides and its Application in Food Processing WANG Lulu,SfflQianqiaii,WANG Yutong,GUXin,JIANG YutBng,*H A N Q i(College of Food Science，Heilongjiang Bayi Agricultural University，Daqing，Heilongjiang 163319，China) Abstract：Soybean bioactive peptides were the hydrolysate of soybean protein，which have been attracted lots of attention due to its various functional activities，and the stability and processing properties of soybean bioactive peptides were better than soybean protein. The functional activities of soybean bioactive peptides，such as antihypertensive，antilipemic，antifatigue and antioxidant，were reviewed in the paper. The application of soybean bioactive peptides in food processing were described and prospected，either. The paper would provide references for the further application of soybean active peptide in food processing.Key words：soybean bioactive peptides;functional activities;food processing;application〇引言大豆蛋白是一种植物源高蛋白食品，蛋白质含 量可达36%~56%，氨基酸组成也十分均衡，包含人 体所需的全部必需氨基酸[1-2]。
木瓜蛋白酶与中性蛋白酶水解大豆分离蛋白的研究钟振声，陈钰，文锡莲（华南理工大学化学与化工学院，广东广州 510640）摘要：研究了大豆分离蛋白经过加热预处理后用木瓜蛋白酶和中性蛋白酶水解的可行性。
以水解度(DH)为指标，考察了单因素水解条件得出：木瓜蛋白酶水解反应的最佳条件为反应底物浓度3.0%，pH 7.0，反应温度55 ℃，酶用量30 μg/g；中性蛋白酶水解反应的最佳条件为反应底物浓度5.0%，pH 7.0，反应温度55 ℃, 酶用量40 μg/g。
在此条件下，大豆分离蛋白水解度分别为3.69%和9.80%。
在一定条件下复合酶分步水解优于单一酶水解。
关键词：木瓜蛋白酶；中性蛋白酶；大豆分离蛋白；水解反应；水解度中图分类号：Q814；文献标识码：A；文章篇号:1673-9078(2009)09-1039-05Hydrolysis of Soybean Protein Isolate by Papain and NeutralProteaseZHONG Zhen-sheng, CHEN Yu, WEN Xi-lian(School of Chemistry and Chemi cal Engineering, South China University of Technology, Guangzhou 510640, China) Abstract: The feasibility of hydrolysis of heat-treated soybean protein isolate (SPI) by papain and neutral protease was studied. Single factor experiment showed that the optimum conditions for papain catalyzed hydrolysis of SPI were as follows: papain dosage 30 μg/g, mass concentration of substrate 3.0%, hydrolysis temperature 55 ℃ and pH 7.0. For neutral protease catalyzed hydrolysis of SPI, the best conditions were neutral protease dosage 40μg/g, mass concentration of substrate 5.0%, hydrolysis temperature 55 ℃, and pH 7.0. Under the above-mentioned two kinds of conditions the hydrolysis degree of protein reached 3.69% and 9.80%, respectively. It was also found that hydrolysis by mixed enzymes was more efficient than that by single enzyme.Key words: papain; neutral protease; soybean protein isolate; hydrolysis reaction; hydrolysis degree大豆分离蛋白的蛋白质含量高达85%-90%，含有丰富的赖氨酸、亮氨酸、苏氨酸和色氨酸等八种人体必需的氨基酸[1]，应用前景十分广阔。
zgrpgy@中国乳品工业0引言液态婴儿配方奶是以水、牛奶、脱盐乳清粉、植物油为原料，添加适量的维生素、矿物质或其它微量有益成分，经超高温(UHT)灭菌处理后，无菌包装而成[1]，既有植物油等脂类物质构成的油相，又有乳蛋白、矿物质、维生素及其他营养素构成的水相，是一种比牛奶更复杂的客观不稳定分散体系，容易出现脂肪上浮、蛋白质沉淀等不稳定现象。
为克服这一缺点，在加工过程中采用均质工艺将脂肪颗粒破碎成较小的脂肪球，使其均匀分散在乳中，有效地防止了产品分层、沉淀。
但均质使脂肪球总表面积增大，原来的成膜物质不足以包裹新生的脂肪球，新产生的表面被乳中的蛋白包裹，导致界面蛋白含量增加，容易与乳清蛋白发生作用，因而使得均质乳的热稳定性降低。
而在实际生产中几乎所有的乳制品都要经过超高温瞬时杀菌(UHT)等热杀菌处理，因而形成稳定的乳状液以抵抗热杀菌防止热凝固是十分必要的。
要达到这一目的，加入适量的表面活性剂是行之有效的方法之一。
大豆磷脂是常用的表面活性剂，是非常有效的稳定剂，能够在较大的pH 范围内(pH 6.3～pH 7.1)提高乳的热稳定性，甚至在均质之后加入也能使乳的热稳定性得到提高[2]。
大豆磷脂和酪蛋白能共同保护新生的脂肪球表面，建立新的脂肪球结构，并能降低热处理过程中吸附的总界面蛋白含量[3]，进而提高乳的热稳定性。
本研究以液态婴儿配方奶蛋白乳状液为基础研究大豆磷脂对牛乳蛋白乳状液热稳定性的影响，研究了添加大豆磷脂对牛乳蛋白乳状液的热凝固时间(HCT)、粒径分布、表面疏水性、Zeta 电位和游离巯基含量的影响，并探讨了相关作用机理，以期为研究大豆磷脂影响牛乳蛋白乳状液热稳定性的机制提供理收稿日期：2009-03-24基金项目：“十一五”黑龙江省科学技术计划攻关项目(GB07B407)。
作者简介：贾娜(1982-)，女，硕士研究生，从事乳品加工与营养研究。
通讯作者：刘宁大豆磷脂对牛乳蛋白乳状液热稳定性的影响贾娜1，2,刘宁1，2（1.黑龙江省乳品工业技术开发中心，国家乳业工程技术研究中心，哈尔滨150086；2.东北农业大学食品学院乳品科学教育部重点实验室，哈尔滨150030）摘要：研究了大豆磷脂对牛乳蛋白乳状液热稳定性的影响，并对相关作用机理进行了探讨。
BASIC NUTRITIONAL INVESTIGATIONSoy Protein Isolate and Its Hydrolysate ReduceBody Fat of Dietary Obese Rats and GeneticallyObese Mice(Yellow KK)Toshiaki Aoyama,PhD,Kensuke Fukui,MSc,Kiyoharu Takamatsu,PhD,Yukio Hashimoto,BS,and Takashi Yamamoto,PhDFrom the Department of Novelty Materials,Research Institute,Fuji Oil Co.,Ltd.,Izumisano,Osaka,JapanThis study examined in dietary obese and genetically obese rodents the effects of soy protein isolate(SPI)and its hydrolysate(SPI-H)on the rate of body-fat disappearance.Male Sprague-Dawley rats(4–16wkold)and yellow KK mice(6–10wk old)were made obese by feeding high-fat diets containing30%fat.They were then fed energy-restricted,low-fat(5.0%),and high-protein(35%casein,SPI,or SPI-H)dietsfor4wk at60%of the level of the energy intake of rodents on laboratory chow.The body-fat contentsof rats and mice fed a high-fat diet were27.3and33.6g/100g body weight,respectively,at the end ofthe obese period.For rats,the apparent absorbability of dietary energy and fat was significantly lower inthe SPI and SPI-H groups than in the casein group,but vice-versa for nitrogen balance.Body-fat contentin mice fed SPI and SPI-H diets was significantly lower than in those fed the casein diet.In rats,plasmatotal cholesterol level was lower with the SPI-H diet,and plasma glucose level was lower with the SPIand SPI-H diets than with the casein diet.These results indicate that SPI and SPI-H are suitable proteinsources in energy-restricted diets for the treatment of obesity.Nutrition2000;16:349–354.©ElsevierScience Inc.2000Key words:obesity,weight reduction,soy protein,protein hydrolysate,body fat,dietary obese rats,genetically obese miceINTRODUCTIONObesity is induced by an imbalance of energy intake and consump-tion.Because overeating is one of the major causes of obesity, restriction of energy intake is the basis of dietary therapy for this disorder.However,simple food restriction reduces not only body fat but also body protein.1The low-energy diet used for the treatment of obese diabetics simultaneously decreases the protein-efficiency ratio.2High-protein diets help maintain body protein when energy intake is restricted.3Protein turnover can be main-tained at a normal level during energy deprivation as long as protein intake is optimized.4Garlick et al.5suggested that weight reduction under energy restriction required protein supplementa-tion.Volgarev et al.6reported that soy protein was effective for reducing weight in obesity,suggesting that the kind of dietary protein influences weight reduction,although they did not compare the effectiveness of soy protein with other proteins.No additional information is available concerning a suitable protein source for diets of weight reduction or energy restriction in obese subjects.Soybean protein has a hypocholesterolemic effect compared with animal proteins such as casein,7,8and it also markedly de-creases the activity of hepatic lipogenic enzymes.9In addition,the weight of brown adipose tissue is higher in rats fed a soy protein diet than in those fed a casein diet.10However,dietary protein affects metabolism of polyunsaturated fatty acids in the liver,and soy protein in relation to casein tends to reduce the metabolism of linoleic acid to arachidonic acid and,hence,the production of several eicosanoids.11Although there is a possibility that these effects may involve the reduction of body fat,it is not clear whether soy protein is suitable as the protein source for weight reduction.Therefore,we investigated the influence of soy protein isolate(SPI)and its hydrolysate(SPI-H)on weight reduction by using dietary obese rats and genetically obese mice. MATERIALS AND METHODSAll animals were treated in accordance with the National Institutes of Health’s Guide for the Care and Use of Laboratory Animals.12 They were housed individually in cages under a controlled atmo-sphere(temperatureϭ23°CϮ1,humidityϭ55%Ϯ5,lightϭ0700–1900h).Table I shows the composition of the experimental diets.Nitrogen content was determined by the Kjeldahl method (Kjeltec Auto1030Analyzer,Nippon General Trading Co.,To-kyo,Japan).SPI-H was prepared by hydrolyzing SPI with protease from Bacillus subtilis(Hynute-D1,Fuji Oil Co.,Osaka,Japan); average peptide chain length wasfive to six.The experimental protocol is summarized in Figure1.Experiment1ANIMALS AND DIETS.Specific pathogen-free3-wk-old male Sprague-Dawley rats,weighing45–60g,were purchased from Japan SLC(Hamamatsu,Japan)and fed commercial pellets (CRF-1,Oriental Yeast Co.,Ltd.,Tokyo,Japan)for5d until they weighed85–100g.Rats were then fed a high-fat diet(containing 30%fat)to induce obesity.One group of7rats was fed commer-cial pellets for12wk(chow group),and another group of26ratsCorrespondence to:Toshiaki Aoyama,PhD,Department of Novelty Ma-terials,Research Institute,Fuji Oil Co.,Ltd.,1Sumiyoshi-cho,Izumisano-shi,Osaka598-8540,Japan.E-mail:aoyama@hkc.fujioil.co.jpDate accepted:Jan.11,2000.Nutrition16:349–354,20000899-9007/00/$20.00was fed a high-fat diet for 12wk (high-fat group).Rats were then randomly assigned to four groups,with the same body weight in each group.Six rats were killed at this stage,and the remaining obese rats were fed energy-restricted diets for additional 4wk (85–112d).Although the number of rats in each restricted group was the same,8rats per group,2rats in the casein and SPI-H groups did not ingest diets during nitrogen-balance measurement,possibly due to a change in the environment.This was not the case for rats in the SPI group.The energy-restricted diets containing 5.6%nitrogen from either casein,SPI,or SPI-H were fed at the level corresponding to 60%of the average daily energy intake by chow-fed rats during 6–18wk of the feeding period.In addition to the observation in rats that the restriction of energy intake to 60%produced a clear difference in growth,the amount of energy humans usually consume was considered.The energy intake of 1200–1600kcal is necessary to maintain human basal metabolism,and this quantity corresponds to about 60%of the amount of energy intake,between 2000and 2500kcal.A similar response might be reproducible if the extent of restriction is adequate.Therefore,we devised an energy restriction of 60%.MEASUREMENT.Food intake and body weight were recorded daily.Feces and urine were collected for 3d every 110–112d.On day 85or 113,food was not provided for 16h (1800–1000h).Blood was drawn from the abdominal aorta into a heparinized syringe under intraperitoneal sodium pentobarbital (15mol/100g body weight)anesthesia,and the liver,epididymal,and perirenal fat pads and the carcass were excised and immediately weighed.Plasma was separated by centrifugation at 1900g for 15min at 5°C and frozen at Ϫ30°C until analyzed.ANALYSES.Feces were freeze dried and powdered with a small electric coffee mill.The energy value of diets and feces was measured with an autocalculating bomb calorimeter (CA-4P,Shi-FIG.1.Experimental protocol in experiments 1and 2.TABLE I.COMPOSITIONS OF EXPERIMENTAL DIETSComponentObesity producing dietEnergy-restricted diet Chow High fat Casein SPI SPI-H Commercial chow*10060.0———Protein source†Casein‡39.1——Soy protein isolate§—41.1—Soy protein hydrolysate ——40.4Cornstarch 36.234.234.9Sucrose 10.010.010.0Shortening¶25.0———Condensed milk#15.0———Soybean oil5.0 5.0 5.0Cellulose powder 5.0 5.0 5.0Mineral mixture** 3.5 3.5 3.5Vitamin mixture** 1.0 1.0 1.0Choline bitartrate 0.20.20.2Protein (%)23.115.035.035.035.0Fat (%)5.930.0 5.0 5.0 5.0Energy (kJ/g)17.223.017.217.217.2*Powdered,CRF-1Oriental Yeast Co.,Tokyo,Japan.†The percentage of nitrogen in each diet was 5.6.‡Oriental Yeast Co.,Tokyo,Japan.§Fujipro-R by Fuji Oil Co.,Osaka,Japan.Hinute-D1,Fuji Oil Co.,Osaka,Japan.Free amino acid content,0.8%.¶Panpas Deluxe by Fuji Oil Co.,Osaka,Japan.#Delicatessen condensed milk,Tsukuba Dairy Products Co.,Ibaraki,Japan.**AIN-7613mixtures,Oriental Yeast Co.,Tokyo,Japan.was analyzed by the Kjeldahl method,and a conversion factor of 6.25was used.The apparent nitrogen balance during the experi-mental diet period was calculated as follows:apparent nitrogen balanceϭINϪFNϪUN,where IN is dietary nitrogen intake, FN is fecal nitrogen,and UN is urine nitrogen output.Total fat content of feces was calculated by the difference of the fecal weight before and after extraction of fat with petroleum ether: acetic acid(50:3,v/v)(Ex-fat,Nippon General Trading Co.,To-kyo,Japan).The apparent digestibilities of energy,protein,and fat were calculated as follows:apparent digestibility(%)ϭ(IϪF)/Iϫ100,where I is dietary energy,protein,or fat intake,and F is fecal energy,protein,or fat output.The carcass including ex-cised tissues was dried by heating at105°C for48h and weighed, and the moisture content was calculated by the difference.Dried carcasses were milled with a mixer,and the protein and fat content was analyzed.The ash content was determined by heating at600°C for4h.Total cholesterol,high-density lipoprotein(HDL)choles-terol,triacylglycerol,and glucose in plasma were measured enzy-matically with the Dry Chem5500auto analyzer(Fuji Film Co., Tokyo,Japan).Experiment2ANIMALS AND DIETS.Five-week-old,male,genetically obese mice(yellow KK mice),weighing26–30g,were purchased from Nihon Clea Co.(Tokyo,Japan)and fed commercial pellet (CRF-1)for7d until they weighed28–32g.Mice were initially fed a high-fat diet(containing30%fat)for31d.Thirty-six obese mice were randomly assigned to three groups.Seven obese mice were killed at this stage;the remaining mice were fed the energy-MEASUREMENTS AND ANALYSES.Food intake and body weight were recorded daily.At58d,the mice were anesthetized with diethyl ether,and tissues were excised after16h of food deprivation(1000–1800h).The body moisture,protein,fat,and ash were measured as described for experiment1.Statistical AnalysesThe results are expressed as meansϮSEM.The results were analyzed by one-way analysis of variance(StatView4.0,Abacus Concepts,Inc.,Berkeley,CA,USA),followed by Duncan’s multiple-range test14to identify significant differences across groups of rats fed energy-restricted diets.In experiment1,the statistical difference between chow and high-fat groups was ana-lyzed by Student’s t test.Differences were considered significant at PϽ0.05.RESULTSTable II summarizes growth parameters and nutrient digestibility of rats in experiment1.The mean food and energy intakes of the chow group were20.0Ϯ0.8g/d and343Ϯ13kJ/d,respectively. The food intake in the high-fat group(17.8Ϯ0.5g/d)was lower, whereas energy intake(410.0Ϯ11.7kJ/d)was significantly higher than those in the chow group(PϽ0.05).Consequently,weight gain in the high-fat group was significantly greater than weight gain in the chow group(382Ϯ112versus299Ϯ18g,PϽ0.05). The food intake during the period of energy-restricted diets was reduced to12.0g/d,corresponding to60%of the energy intake in the chow group.Rats fed SPI and SPI-H diets tended to reduce body weight more than those fed the casein diet.Fecal weights of rats fed SPI and SPI-H diets tended to be greater than in those fed the casein diet,but the difference was not statistically significant.TABLE II.BODY WEIGHT,FOOD INTAKE,FECAL EXCRETION,AND APPARENT DIGESTIBILITY OF NUTRIENTS AND ENERGY IN RATS FEDREFERENCE AND ENERGY-RESTRICTED DIETS(EXPERIMENT1)*Reference group Energy-restricted groupChow(7)High fat(6)Casein(6)SPI(8)SPI-H(6) Initial body weight(g)92.0Ϯ2.0†94.4Ϯ2.3491Ϯ21503Ϯ15499Ϯ15 Final body weight(g)391Ϯ20†476Ϯ12436Ϯ15442Ϯ12437Ϯ15 Weight gain(g/d) 3.6Ϯ0.2† 4.5Ϯ0.1Ϫ2.0Ϯ0.3Ϫ2.2Ϯ0.2Ϫ2.2Ϯ0.1 Food intakeDiet(g/d)20.0Ϯ0.8†17.8Ϯ0.511.7Ϯ0.111.7Ϯ0.111.6Ϯ0.1 Energy(kJ/d)343.0Ϯ13.8†410.0Ϯ11.7201.0Ϯ1.7200.0Ϯ0.8199.0Ϯ0.8 Protein(g/d) 4.6Ϯ0.2† 2.7Ϯ0.1 4.1Ϯ0.1 4.1Ϯ0.1 4.1Ϯ0.1 Fat(g/d) 1.2Ϯ0.1† 5.3Ϯ0.20.6Ϯ0.10.6Ϯ0.10.6Ϯ0.1 Fecal excretionFeces,dry weight(mg/d)3641Ϯ177†2165Ϯ731046Ϯ331127Ϯ351128Ϯ35 Energy(kJ/d)60.2Ϯ2.9†43.1Ϯ2.116.3Ϯ0.4a18.8Ϯ0.4b20.1Ϯ0.8b Protein(mg/d)925Ϯ45†311Ϯ25237Ϯ22a275Ϯ16ab304Ϯ6b Fat(mg/d)136Ϯ10†382Ϯ1238.3Ϯ3.8a54.2Ϯ3.1b61.1Ϯ3.2b Apparent digestibilityEnergy(%)80.8Ϯ0.2†87.4Ϯ0.392.3Ϯ0.2b90.0Ϯ0.3a90.4Ϯ0.3a Protein(%)77.9Ϯ0.678.1Ϯ1.294.1Ϯ0.693.3Ϯ0.492.3Ϯ0.7 Fat(%)86.8Ϯ0.6†93.4Ϯ0.393.5Ϯ0.7b90.5Ϯ0.5a89.3Ϯ0.5a *Values are meansϮSE.Number of rats is given in parentheses.Among energy-restricted groups,values in the same row with different superscripts are different at PϽ0.05.†PϽ0.05,chow versus high fat by Student’s t test.SPI,soy protein isolate;SPI-H,soy protein isolate hydrolysate.than did those fed casein,whereas energy and fat excretion in the SPI and SPI-H groups was significantly higher than that in the casein group.Therefore,the apparent digestibility of dietary en-ergy and fat in the SPI and SPI-H groups was significantly lower than that in the casein group.Body weight gain in experiment2during the energy-restricted diet period is shown in Table III.The food and energy intakes and weight gain of mice during the initial high-fat diet were5.2g/d, 120.0kJ/d,and0.54g/d,respectively(data not shown).The amount of diet consumed during energy-restricted diets was re-duced to3.0g/d,and mice fed the SPI-H diet lost more weight than those fed the casein diet for2–3wk(PϽ0.05).In experiment1,the nitrogen balance during energy-restricted diets was negative,and it was in the order of casein,SPI,and SPI-H(Table IV).As shown in Table V,the relative liver weight in rats fed the SPI-H diet was significantly lower than that in those fed the casein diet and was intermediate in those fed the SPI diet.A similar trend was observed in the weight of fat pads,but the difference was not significant.In mice the liver weight was comparable across the three restricted groups,but the weight of fat pads was significantly lower in the two vegetable-nitrogen groups than in the animal-protein group.The body-fat contents of rats and mice fed the high-fat diet were27and29g/100g body weight,respectively,and they lost weight on the energy-restricted diets(Table VI).Body fat in rats and mice fed the SPI and SPI-H diets tended to be lower than the body fat in those fed the casein diet,and the difference in mice was significant.Water,nitrogen,and ash content in the SPI and SPI-H groups tended to be higher than those in the casein group,and the ash content was significantly different between the casein and SPI-H groups(Table VI).In experiment1,plasma total cholesterol and HDL cholesterol levels were significantly lower in rats fed the SPI-H,but not SPI, diet than in those fed the casein diet(Table VII).Plasma triacyl-glycerol levels also tended to decrease more in rodents fed the SPI and SPI-H diets than those fed the casein diet.Plasma glucose level was significantly reduced in the two groups of rats fed vegetable-nitrogen sources,and the degree of the reduction was more marked in the SPI-H than in the SPI group. DISCUSSIONIn this study,we examined the effects of SPI and SPI-H on body-fat amount in dietary obese rats and genetically obese mice. The results suggest that these diets are better than casein as a dietary protein source to reduce body fat while maintaining body nitrogen.During diet therapy of obese patients,it is important to main-tain body nitrogen and restrict energy intake.Therefore,supple-mentation of the proper protein source is needed.In this study,rats and mice fed soy protein recovered more effectively from obesity than did the animals fed casein.Thus,the body fat in rats and mice fed SPI and SPI-H was lower than that in those fed casein. Whereas no difference was observed in body-protein content across the three different nitrogen sources,rats fed SPI and SPI-H showed lowered fat and energy digestibility due to an increase in fecal-fat excretion.The difference attributable to the change in digestibility between casein and SPI-H groups was estimated to be 2.5–5.0kJ,i.e.,about1kcal.Consequently,the difference in the decrease in body fat across groups cannot be explained by the difference in energy absorption alone.Baba et al.15and Shinjyo et al.16reported in rats that the soy-protein versus the casein diet reduced body fat and serum insulin levels significantly.Soy protein affected the conversion of thyroxine to triiodothyronine17and suppressed hepatic lipogenic enzyme gene expression in Wistar fatty rats.18Barth and Pfeuffer19 observed that feeding soy protein isolate resulted in a significantly higher total thyroxine concentration in serum than did casein in minipigs.Forsythe20also reported that gerbils fed soy protein had significantly higher plasma thyroxine and thyroid-stimulating hor-mone levels than did those fed casein.From these observations it is suggested that SPI and SPI-H alter the hormone balance and in turn accelerate lipid metabolism.TABLE III.BODY WEIGHT IN MICE FED ENERGY-RESTRICTED DIETS(EXPERIMENT2)*Casein(12)SPI(12)SPI-H(12)Initial body weight(g)46.8Ϯ0.446.8Ϯ0.446.8Ϯ0.4Weight reduction(g)1wk39.3Ϯ0.339.0Ϯ0.338.6Ϯ0.42wk36.9Ϯ0.3b36.2Ϯ0.3ab35.5Ϯ0.4a3wk36.0Ϯ0.3b35.4Ϯ0.3ab34.8Ϯ0.3a4wk35.7Ϯ0.335.5Ϯ0.335.1Ϯ0.3*Values are meansϮSE.Number of rats is given in parentheses.Among energy-restricted groups,values in the same row with differentsuperscripts are different at PϽ0.05.SPI,soy protein isolate;SPI-H,soy protein isolate hydrolysate.TABLE IV.APPARENT NITROGEN BALANCE IN RATS FED REFERENCE AND ENERGY-RESTRICTED DIETS(EXPERIMENT1)*NitrogenReference diet Energy-restricted dietChow(7)High fat(6)Casein(6)SPI(8)SPI-H(6)Intake(mg/3d)1896Ϯ93‡1048Ϯ361774Ϯ10a1839Ϯ15b1811Ϯ10b Fecal(mg/3d)435Ϯ21‡241Ϯ9111Ϯ10a129Ϯ6ab145Ϯ3b Urinary(mg/3d)1375Ϯ73‡653Ϯ351742Ϯ151769Ϯ401715Ϯ35 Balance(mg/3d)†86Ϯ21153Ϯ30Ϫ78Ϯ20Ϫ59Ϯ24Ϫ49Ϯ33 *Values are meansϮSE.Number of rats in parentheses.Among energy restricted groups,values in the same row with different superscripts are dif-ferent at PϽ0.05.†Apparent nitrogen balance.‡PϽ0.05,chow versus high fat,by Student’s t test.The hydrophobic high-molecular-weight fraction of soy protein appeared to affect lipid metabolism,21and this fraction is regarded as the principal component22responsible for lowering serum total cholesterol and triacylglycerol activity of soy protein.These hy-polipidemic effects may also relate to the reduction of body fat. The SPI-H used in the present study contained a hydrophobic high-molecule-weight fraction.Our study also showed a signifi-cant hypocholesterolemic effect of SPI-H compared with casein. Lowering the total plasma cholesterol level may well be concerned with the reduced absorption of cholesterol and fat and,hence,the reduction of body-fat accumulation.It is interesting to know whether the observed beneficial effects of SPI and in particular SPI-H can be attributable to the change in brown adipocyte activity because several studies with SPI-H have indicated this possibility.23,24One plausible explanation of the different response of liver and adipose tissue weight between rats and mice is the different met-abolic characteristics of those rodents.It seems likely that mice are less tolerant than rats to energy restriction.In this context,it is known that the fat in the liver is used earlier than that in epidid-ymal and perirenal fat pads.In conclusion,the present results indicated that SPI and SPI-H reduce body fat in genetically obese mice and accelerate lipid and energy metabolism,suggesting their beneficial property as theRELATIVE LIVER,EPIDIDYMAL,AND PERIRENAL FAT-PAD WEIGHT OF RATS AND MICE FED REFERENCE AND ENERGY-RESTRICTED DIETS(EXPERIMENTS1AND2)*Reference group Energy-restricted groupChow High fat Casein SPI SPI-H Experiment1n76686 Liver weight(g/100g bw) 2.98Ϯ0.20 3.17Ϯ0.11 2.86Ϯ0.10b 2.60Ϯ0.07ab 2.47Ϯ0.02a Fat-pad weightEpididymal(g/100g bw) 2.16Ϯ0.13† 3.41Ϯ0.12 3.12Ϯ0.08 2.81Ϯ0.18 2.71Ϯ0.25 Perirenal(g/100g bw) 2.58Ϯ0.13† 4.38Ϯ0.17 3.69Ϯ0.31 3.60Ϯ0.23 3.12Ϯ0.37 Experiment2n7121212 Liver weight(g/100g bw) 6.69Ϯ0.27 3.87Ϯ0.10 3.66Ϯ0.06 3.67Ϯ0.08 Fat-pad weightEpididymal(g/100g bw) 3.55Ϯ0.11 2.17Ϯ0.10b 1.88Ϯ0.09a 1.84Ϯ0.05a Perirenal(g/100g bw) 2.80Ϯ0.12 2.57Ϯ0.10b 1.87Ϯ0.09a 1.94Ϯ0.94a *Values are meansϮSE.Among the energy-restricted groups,values in the same row with different superscripts are different at PϽ0.05.†PϽ0.05,chow versus high fat,by Student’s t test.bw,body weight;SPI,soy protein isolate;SPI-H,soy protein isolate hydrolysate.TABLE VI.BODY COMPOSITION OF RATS AND MICE FED REFERENCE AND ENERGY-RESTRICTED DIETS(EXPERIMENTS1AND2)*Reference group Energy-restricted groupChow High fat Casein SPI SPI-H Experiment1n76686 Carcass weight(g)374Ϯ20†447Ϯ13410Ϯ14412Ϯ12407Ϯ14 Water(%)58.3Ϯ0.5†51.3Ϯ0.753.6Ϯ0.754.5Ϯ1.856.1Ϯ5.5 Protein(%)19.3Ϯ0.2†17.2Ϯ0.318.6Ϯ0.319.1Ϯ0.319.2Ϯ0.5 Fat(%)18.2Ϯ0.6†27.3Ϯ1.023.4Ϯ0.721.7Ϯ0.919.4Ϯ2.4 Ash(%) 3.2Ϯ0.1† 2.8Ϯ0.1 3.1Ϯ0.1 3.3Ϯ0.2 3.4Ϯ0.2 Experiment2n7121212 Carcass weight(g)37.0Ϯ0.529.8Ϯ0.329.1Ϯ0.428.6Ϯ0.3 Water(%)48.4Ϯ0.351.6Ϯ0.853.1Ϯ0.553.2Ϯ0.5 Protein(%)14.4Ϯ0.215.6Ϯ0.2a16.6Ϯ0.1c16.1Ϯ0.1b Fat(%)33.6Ϯ0.429.1Ϯ0.7b26.5Ϯ0.5a26.4Ϯ0.3a Ash(%) 2.7Ϯ0.1 3.2Ϯ0.1a 3.3Ϯ0.1ab 3.4Ϯ0.1b *Values are meansϮSE.Among energy-restricted groups,values in the same row with different superscripts are different at PϽ0.05.†PϽ0.05,between chow versus high fat,by Student’s t test.nitrogen source even in energy-restricted diets.The diet-induced obese rats also responded similarly but to a lesser extent.There-fore,the soy-protein products may be recommended as a nitrogen source in energy-restricted diets.SUMMARYBody-fat content and total plasma cholesterol and glucose levels in animals fed SPI and SPI-H diets were significantly lower than in those fed the casein diet under the condition of energy restriction. These results indicate that SPI and SPI-H are suitable protein sources in energy-restricted diets for treatment of obesity. ACKNOWLEDGMENTSThe authors are indebted to Prof.M.Sugano of the Prefectural University of Kumamoto and Prof.S.Yamamoto of the University of Tokushima for support and encouragement of this study and for helpful suggestions during the preparation of the manuscript. 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