脂类对反应型香精风味形成影响的研究

根据3种不同原料所含主要脂肪酸及不饱和度的不同,通过反应所生成主要风味物质差异来进一步探讨反应型香精风味形成机理。     

Short communication: Volatiles in microfluidized raw and heat-treated milk

As innovative processing equipment is introduced to milk processing, it is essential to determine its effect on milk aroma, a critical factor in consumer acceptance of the final dairy product. Microfluidization is known to cause severe high-pressure homogenization of milk fat and, although severe processing is known to release undesired aromas, no information is available on the levels of the volatile compounds in milk immediately after microfluidization. We hypothesized that microfluidization would alter levels of volatile compounds in milk that may affect aroma. The concentration of 11 selected volatile compounds in raw, thermized, pasteurized, and UHT 3.0% fat milk samples were compared before and after microfluidization at 170 MPa and common 2-stage homogenization at 15 MPa. Overall, the different milk samples had similar trends in response to homogenization, although UHT milk started with lower values of nonanoic acid, and acetone and higher levels of hexanal and heptanol. In many cases, microfluidization did not significantly alter volatile levels compared with the starting milk. Heptanal was the only compound observed to increase in thermized and UHT milk, whereas nonanoic acid and acetone decreased in raw, thermized, and pasteurized milks and octanoic acid decreased in thermized and UHT milks. The highest levels of almost all of the volatiles were found in the 2-stage homogenized milk. Overall, microfluidization had minimal effect on the volatile compound profiles of milk, although sensory evaluation is needed to confirm effects on aroma and flavor.     

中国白酒的非酶褐变反应的应用

食品在加热处理或长期贮存中，会产生不同程度的类黑精色素，这类反应没有酶的参与，故称非酶褐变反应。白酒在长期贮存中出现微黄色或淡黄色，属非酶褐变反应。白酒中的非酶褐变反应受白酒中微量成分的种类及含量、水分、pH值、温度、时间、金属离子和氧等因素影响。可利用非酶褐变反应鉴别酒曲培制温度及中挺时间、白酒香型和检测产品质量。     

Production of Off-Odor Volatiles from Liposome-Containing Amino Acid Homopolymers by Irradiation

Irradiation not only generated many new volatiles but also destroyed some volatiles already present in nonirradiated amino acid homopolymer‐in‐liposome systems. The amounts of some volatiles greatly increased, but others significantly decreased after irradiation. The majority of newly generated and increased volatiles by irradiation were sulfur compounds, indicating that sulfur amino acids are the most susceptible to changes by irradiation. More than one site in amino acid side chains was labile to free radical attack, and many volatiles were produced by the secondary chemical reactions after the primary radiolytic degradation of side chains. Although nonirradiated samples also produced some sulfury notes, irradiated samples produced much a stronger and astringent sulfury odor than nonirradiated samples.     

pH对墨鱼酶解物美拉德反应产物风味的影响

本实验以墨鱼酶解液和葡萄糖-木糖混合糖为原料,通过气相色谱-质谱联用仪(GC-MS)结合电子鼻、全自动氨基酸分析仪感官评价,研究了不同初始pH对美拉德反应产物风味的影响。结果表明:在初始pH(5~7)反应条件下,随着反应初始pH升高,产物腥味减轻,鲜甜味突出,挥发性化合物中醛类物质相对含量由58.25%增加至60.9%,呋喃类物质由28.26%降低至16.95%,游离氨基酸总含量由5.725 mg/mL增加至6.303 mg/mL;初始pH(8~10)反应条件下,随着反应初始pH升高,产物鲜甜味减轻,糊味突出,同时挥发性化合物中醛类物质相对含量由54.29%降低至26.62%,吡嗪类物质相对含量由0增加至18.41%,游离氨基酸总含量由5.948 mg/mL降低至4.945 mg/mL。同时随着反应初始pH升高(5~10),三甲胺相对含量由0.05%升高至32.79%,含硫化合物相对含量由0升高至12.33%,说明不同初始pH下墨鱼酶解液美拉德反应产物的风味不同。     

酪蛋白的酶促水解及其水解物的美拉德反应

以酪蛋白为原料，经蛋白酶催化水解，得到蛋白水解液，进而和糖进行美拉德反应制成新型非酶棕色化香料。水解酶为胰蛋白酶和木瓜蛋白酶。本文利用正交试验设计，系统地研究了蛋白酶催化条件下酪蛋白的水解，研究了各实验因素对水解效率的影响。最佳水解条件是：水解温度50℃，pH8．0，水解时间24h，酶-底物浓度比0．5％～1．0％。美拉德反应合成的新型非酶棕色化香料，具有浓郁的烤土豆香味。可应用于食品和烟草的加香。     

美拉德反应产物抗氧化活性

该文综述美拉德反应产物抗氧化活性及其国内外研究进展,并对其抗氧化机理进行一些探讨。     

小麦蛋白酶解物制备热反应型肉香调味基料的研究

该研究以深度酶解的小麦面筋蛋白为主要原料,利用控制条件下的美拉德反应,制备得到了肉香风味物质,并采用固相微萃取-气相-质谱技术(SPME-GC-MS)对产物的挥发性组分进行了鉴定。结果表明,体系组成(半胱氨酸和木糖添加量)和反应条件(温度、pH、时间)均对肉香风味物质的形成产生重要影响,其程度为pH值>半胱氨酸用量>温度>时间>木糖用量。通过正交试验对工艺进行优化,得到制备肉香风味物质的最佳条件为：添加15%小麦面筋蛋白酶解物、6%木糖、1.25%半胱氨酸,于pH 7、115 ℃条件下反应75 min。从该工艺制备的产物中共鉴定出46种风味化合物,其中2-甲基-3-呋喃硫醇的相对含量较高,对肉香风味的形成起到了重要作用。     

Investigation of interactions between silicones and stratum corneum lipids

Ingredients of topically applied skin care formulations have not only positive effects on the appearance of human skin but can also disturb the Stratum corneum (SC) lipid barrier. In the present study, the influence of silicones (PDMS), as often used cosmetic ingredients, on the microstructure of SC lipids was investigated. For this purpose the interactions of four different PDMS with excised human SC were examined first using differential scanning calorimetry (DSC) and wide angle X-ray diffraction for physical characterization. Because the physical properties of human stratum corneum strongly depend on the lipid composition, showing inter-and intra-individual differences, the interactions with an in vitro model lipid system containing SC fatty acids were also studied, using polarized light microscopy, transmission electron microscopy, small angle X-ray diffraction and DSC. The results revealed that the investigated PDMS do not change either the microstructure of excised human SC or the biphasic lamellar/inverse hexagonal structure of the in vitro model. We concluded that PDMS will not cause any side-effects when topically applied and that our simplified in vitro model could be helpful for estimating interactions between cosmetic ingredients and other topically applied substances and the skin barrier at an early moment of formulation development.     

酶解—美拉德反应修饰改善烟草薄片品质的研究

在果胶酶—漆酶复合酶解的烟末提取浓缩液中添加一定量的氨基酸、短肽和果糖进行美拉德反应,制得优化处理组薄片。以市售薄片为对照,通过感官评吸、GC—MS—O等方法,对薄片感官品质、香气成分,烟气粒相物成分进行了分析。结果表明,相比于对照组,处理组薄片的香气成分中有利成分大多有所增加,大马士酮提高192.0%,巨豆三烯酮1提高356.0%;烟气粒相物中部分不利成分有所下降,4-乙烯基愈创木酚含量下降100%。处理组感官评吸得分明显提高,香气更加丰富、协调,焙烤香浓郁,杂气、刺激性减小,抽吸品质明显改善。     

烟末酶解物美拉德反应配料的优化

以烟末酶解物为基液,通过添加不同的氨基酸与糖类,进行美拉德反应,选择出合适的氨基酸与糖,同时通过GC-MS检测了氨基酸与部分糖类发生的美拉德反应。结果表明:从评吸得分和褐变程度来看,甘氨酸和木糖是比较合适的氨基酸和糖类,且糖氨比为2:1时,具有良好的风味;GC-MS结果表明:随着糖类的加入,产生了以吡嗪类、呋喃类、吡咯类及醛类为代表的25种风味物质。三种糖都产生了大量的糠醇,且木糖产生了其它两种糖所没有的6种呋喃类物质,同时风味得到了很好的改善。     

论美拉德反应产物与浓香型低度白酒

美拉德反应存在于各类白酒的发酵过程中,其产物对不同香型白酒的呈香呈味都起着或多或少的增强、修饰作用,它可以通过强化发酵而获得提高。美拉德产物在酸性介质中成盐后具有很好的水溶性和较低的阁值,在改善低度白酒的混浊、味淡、延长货架期等方面具有积极的作用。     

Volatile Compounds Recovered by Solid-Phase Microextraction from Fresh Adductor Muscle and Total Lipids of Sea Scallop (Placopecten magellanicus) from Georges Bank (Nova Scotia)

ABSTRACT: The volatile compounds of the adductor muscle of the sea scallop Placopecten magellanicus were recovered by solid-phase microextraction using both polydimethylsiloxane and polydimethylsiloxane/divinylbenzene-coated fibers. Gas chromatography/mass spectrometry revealed the presence of 34 compounds, including 7 long-chain alcohols, 6 aldehydes, and 6 ketones. Two sulfur-containing volatiles were also identified. Six aldehydes, 3 alkanes, and 3 alcohols were tentatively identified from the total lipid fraction. The profiles obtained with the 2 fibers was different because of polarity and polymer differences. The fatty-acid compositions of the total lipid and of the phospholipid class were determined. Phospholipids with 95% of the total lipid are potentially a source of fatty-acid oxidation products.     

两种干燥方式对油茶籽美拉德反应的影响

本文考察了烘箱和微波辐射两种干燥方式对油茶籽美拉德产物抗氧化性的影响。通过测定油茶籽中美拉德产物丙酮醛、乙二醛、3-脱氧奥苏糖含量等指标考察了油茶籽在不同干燥方式中氧化稳定性的变化规律。结果表明:随着微波加热时间的延长,各火力下的油茶籽均具有清除DPPH自由基的能力。在微波高火下加热20 min时清除DPPH自由基能力最强为93.11%。在150℃加热90 min清除DPPH自由基能力最强为92.03%。在微波加热0～10 min时,在美拉德反应中主要影响油茶籽抗氧化性的物质是5-羟甲基糠醛;在微波加热15 min后,主要影响油茶籽抗氧化性等物质是丙酮醛和3-脱氧奥苏糖。在烘箱加热方式下主要影响油茶籽抗氧化性的物质为丙酮醛、3-脱氧奥苏糖和5-羟甲基糠醛。油茶籽中乙二醛含量对其抗氧化性作用不大。本文的研究结果对探究油茶籽油美拉德反应的抗氧化机理以及优化油茶籽加工工艺提供了理论基础。     

甜菊苷对葡萄糖-氨基酸美拉德反应模型褐变强度及抗氧化活性的影响研究

作为低热高甜的新型糖源甜菊苷在食品工业中使用范围日益广泛,甜菊苷赋予食品甜感的同时也影响食品的加工品质,为探讨甜菊苷对美拉德反应的影响及在食品工业中的应用提供理论参考。通过建立葡萄糖与氨基酸之间的美拉德反应模型体系,考察甜菊苷添加量、反应温度、反应时长和初始pH条件对葡萄糖-甘氨酸、组氨酸、谷氨酸、半胱氨酸、苯丙氨酸美拉德反应褐变强度、抗自由基能力及总还原能力的影响。结果表明:在12mL 50mmol/L葡萄糖-氨基酸磷酸缓冲溶液反应体系中,甜菊苷添加量0.100g,加热温度为120℃、反应时间为90min、体系初始pH为8时,甜菊苷能够有效抑制褐变强度,抗氧化能力和反应历程因氨基酸类别而不同。为进一步研究甜菊苷在食品工业生产中与食品组分之间发生化学反应,以及在甜菊苷作用下美拉德反应机制奠定了初步理论基础。     

全面认识谷物原料清液发酵生产酒精

从原料综合利用和技术进步等角度分析了谷物原料清液发酵生产酒精的优劣，提倡谷物原料综合利用走清液发酵生产酒精之路。     

Effects of supercritical carbon dioxide on volatile formation from Maillard reaction between ribose and cysteine

BACKGROUND: Supercritical carbon dioxide (SC‐CO₂) technology is being used in an increasing number of food‐manufacturing applications; however, its effect on the Maillard reaction is not well studied. The objective of this study was to investigate the effect of SC‐CO₂ treatment (140 °C, 40 MPa) on the Maillard reaction of an aqueous ribose–cysteine model system under varying pH conditions (5.6, 7.0 and 8.0), with emphasis on the formation of volatile compounds. RESULTS: SC‐CO₂ had a suppressing effect on the browning stages of the reaction under acidic and neutral pH conditions, while it appeared to have an accelerating effect at pH 8.0. Over 70 volatile compounds were positively identified from the headspace of the model system by gas chromatography–mass spectrometry. The volatiles were dominated by sulfur‐containing compounds including thiophenes and fused bicyclic sulfur‐containing compounds under all experimental conditions. Several compounds, including 2‐methyl‐3‐furanthiol, 2‐furanmethanethiol, 3‐thiophenethiol, and 2‐methyl‐3‐thiophenethiol, and one of the intermediates, furfural, were generated in much higher amounts in the SC‐CO₂‐treated samples, especially at alkaline and neutral pH values. CONCLUSION: SC‐CO₂ treatment was inhibitory to the formation of most volatiles in the Maillard reaction, but enhanced the formation of some intermediates and well‐known meaty flavoured compounds. Copyright © 2007 Society of Chemical Industry     

马氏珠母贝肉美拉德反应产物抗氧化及抑菌活性研究

以木瓜蛋白酶水解马氏珠母贝肉得到的水解液为原料,分别与葡萄糖、果糖和麦芽糖发生美拉德反应,并对3种美拉德反应产物进行抗氧化和抑菌活性测定。结果表明,3种反应产物均具有一定的抗氧化能力和抑菌活性,抗氧化能力随着美拉德产物浓度的升高而增强,尤其是葡萄糖的美拉德反应产物比其他2种糖的反应产物的抗氧化和抑菌能力更强,葡萄糖美拉德产物浓度在10%时,对羟基自由基和超氧阴离子自由基的清除率高达27.35%和13%,均高于其他2种糖美拉德产物的清除率;3种糖的美拉德产物对大肠杆菌、芽孢杆菌、巴氏杆菌的抑制率随美拉德产物浓度的升高而加强,但对沙门氏菌3种美拉德产物却都没有显示出抑制作用。     

Effects of lard on the formation of volatiles from the Maillard reaction of cysteine with xylose

BACKGROUND: The presence of lipid oxidation products in the Maillard reaction pathway is of particular interest today. The objective of this study was to investigate the effect of lard and its oxidation products on the formation of volatiles from cysteine and xylose model systems. RESULTS: Headspace volatiles generated in reaction mixtures were examined by solid‐phase microextraction in combination with gas chromatography‐mass spectrometry. The addition of lipid had a suppressing effect on most of the sulfur‐containing compounds derived from the reaction between cysteine and xylose, especially for 2‐methyl‐3‐furanthiol, 2‐furanmethanethiol, 2‐methylthiophene, and 3‐methylthiophene. One of the intermediates—furfural—was also formed in much lower concentration when lard was present. In addition, cysteine and xylose modified lipid oxidation pathways, so that lipid‐derived alcohols, alkylfurans and aliphatic acids were formed rather than aldehydes. Compared with the lard heated alone, most aldehydes were formed at lower levels in the lard‐containing reaction mixtures, and several aldehydes including hexanal, heptanal, (2E)‐heptenal and (2E,4E)‐heptadienal were absent. CONCLUSION: The addition of lipid was inhibitory to the formation of most sulfur‐containing compounds in the Maillard reaction. Furthermore, Maillard reaction products influenced the formation of products from lipid oxidation. Copyright © 2011 Society of Chemical Industry     

Changes of Headspace Volatiles in Milk with Riboflavin Photosensitization

ABSTRACT:  Effects of fluorescent light, riboflavin, ascorbic acid, sodium azide, and butylated hydroxyanisole (BHA) on the volatiles in milk at 4 °C were determined using a combination of headspace-solid phase microextraction (HS-SPME), gas chromatography (GC), and mass spectrometry (MS). Pentanal, hexanal, heptanal, and dimethyl disulfide were formed only in the milk stored under light and increased significantly as the duration of light exposure increased from 0 to 8 h and the concentration of added riboflavin increased from 5 to 50 ppm ( P  < 0.05). As fat content in milk increased, peak areas of pentanal, hexanal, and heptanal increased significantly ( P  < 0.05) while those of dimethyl disulfide did not change significantly ( P  > 0.05). Sodium azide prevented the formation of dimethyl disulfide in milk, implying that dimethyl disulfide can be formed through singlet oxygen oxidation (type II pathway). Addition of ascorbic acid and BHA reduced the formation of hexanal, heptanal, and dimethyl disulfide significantly ( P  < 0.05). Generation mechanisms of pentanal seem to be different from those of hexanal and heptanal in milk. Both singlet oxygen oxidation (type II pathway) and free radicals (type I pathway) play important roles in the formation of light-induced volatiles in milk.