Immunochemical study of changes in the soluble proteins of wheat during germination

During germination and early growth the general immuno-electrophoretic pattern of soluble proteins of two wheat species showed similar changes. Several of the antigenie proteins detected, including the esterase and peroxidase, did not appear to be modified up to 13 days from the start of germination. Others decreased in quantity or disappeared altogether. In contrast to the esterase and peroxidase, the amylolytic enzymes exhibited marked changes. The antigenic β-amylases existing in electrophoretically different forms in the mature wheat seeds appeared to change to an electrophoretically more homogeneous form in germinated seeds. The (β-amylase in germinated wheat seeds retained its antigenic resemblance to the forms of the mature seeds but differed in other aspects from these isozymes. The antigenic α-amylase of germinated seeds was shown to be absent from the mature seeds, even as an inactive-form. Its increase in activity during germination was ascribed to a synthesis rather than activation of a precursor or proenzyme.     

Immunochemical quantification of heat denaturation of camel ( Camelus dromedarius ) whey proteins

The major whey proteins IgG, serum albumin and alpha-lactalbumin were purified from camel milk using gel permeation and ion-exchange chromatography. Specific antisera against each of them were raised and used to quantify their heat denaturation in early or mature milk over a range of 60-90 degrees C for 10-60 min using the single radial immunodiffusion technique. The heat denaturation midpoints for the mature milk heated 30 min were 67.2, 73.0 and 77.5 degrees C for IgG, albumin and alpha-lactalbumin respectively. The early milk was more sensitive to heat treatment with coagulation at low temperature and heat denaturation midpoints of 64.8, 71.6 and 72.6 degrees C respectively. This difference was related to the high IgG content of the early milk (12.6 mg/ml v. 0.5 mg/ml for the mature milk) and stresses the importance of monitoring the IgG level of milk to assess the absence of colostrum.     

Immunochemical examination of the surface physico-chemical properties of various dicotyledonous and monocotyledonous globulin seed storage proteins

Immunochemical analysis of the surface properties of seed globulins indicated that the 11S seed globulins of monocotyledonous and dicotyledonous plants possibly share some similarity in their primary structures, i.e. amino acid sequence on their surface topography as well in their structural conformation. Although homologies were found in all globulins, stronger antigenic responses were found to occur between the amaranth globulin antibody and the purified globulins from monocotyledonous than those originating from dicotyledonous seeds. Homologies in primary structure were found to occur almost exclusively in the ‘basic’ (20–27 000 Da) type subunit of the respective globulins. Data would imply that gene families encoding for these different proteins were derived from a common ancestral gene and must have been present before divergence of the angiosperms into dicotyledonous and monocotyledonous plants.     

不同柑橘品种对柑橘果酒香气成分的影响

采用顶空固相微萃取-气质联用技术对由脐橙、锦橙、椪柑和蜜柑所酿造的柑橘果酒的香气成分进行分析。结果表明,在4种柑橘果酒中共分离鉴定出43种香气化合物,其中包含酯类、醇类、酸类、醛类、酮类、烃类等,主要的香气贡献成分是酯类化合物,相对含量在58%~68%之间。柑橘果酒主体香气成分有乙酸乙酯、乙酸异戊酯、3-苯丙酸乙酯、乳酸乙酯、己酸乙酯、庚酸乙酯、壬酸乙酯、癸酸异戊酯、癸酸乙酯、月桂酸乙酯、苯甲酸乙酯、异戊醇、苯乙醇、2-乙基己醇、辛酸、月桂酸、2-氨基苯乙酸、苯乙醛、4-苯基丁醛、苯乙烯等,这些成分是决定柑橘果酒酒香和果香的重要组分。而锦橙果酒中这类化合物含量最高,且其感官评分也最高。因此,川南地区宜选锦橙用于柑橘果酒的制作。     

The interfacial behaviour of three food proteins studied by the drop volume technique

The adsorption behaviour of three food proteins, a soy protein isolate, a sodium casein-ate and a whey protein concentrate, at the air-water interface has been studied by the drop volume method. The kinetics of surface tension decay were evaluated in terms of different rate-determining steps at different ionic strengths and concentrations. This analysis indicates the following characteristics concerning the surface behaviour of the protein systems studied. The soy proteins diffuse slowly to the interface compared to the other proteins, probably due to the large particle size of the association complex of soy proteins. For the soy proteins, diffusion is slower in distilled water than in 0.2M-NaCl solution and spreading of molecules at the interface is most easily performed in 0.2M-NaCl solution. The whey proteins diffuse quickly to the interface, which is in accordance with their aqueous association; mainly small molecular complexes. Diffusion is slower and spreading easier in distilled water than in 0.2M-NaCl solution. Although the caseinate has a complex quaternary structure, like the soy proteins, it has a very different surface behaviour. The diffusion step is rapid at concentrations above 10^?3 wt % and contributes to a large extent to the interfacial tension decay, especially when the caseinate is dispersed in 0.2M-NaCl solution. At a concentration of 10^?3 wt % and below, the rate of the diffusion step is slowed down drastically, with an accompanying drop in the surface activity of the protein. This type of surface behaviour can be explained if the migration of the caseinates to the interface takes place via the casein monomers in the bulk phase.     

Utilisation of orange by-products—orange peel carotenoids

Carotenoids were extracted from fresh orange peel with various solvents. Acetone was the most efficient of the solvents tested. Two successive extractions with acetone after an initial washing with either acetone or methanol were adequate to remove 89% of the total carotenoids. The extracts were concentrated, the carotenoids transferred to hexane and a crude pigment concentrate was obtained by hexane evaporation. Water washings prior to acetone extraction eliminated the solvent-solvent transfer to hexane. The extraction residue was used for pectin recovery. Carotenoid removal from the peel did not affect the yield and quality of the pectin.     

Influence of milk proteins on the pasting behaviour and microstructural characteristics of waxy maize starch

Gelatinisation of 5 wt% waxy maize starch (WMS) under shear (16.8 s⁻¹), alone and in mixtures with 5 wt% α-lactalbumin (α-lac), β-lactoglobulin (β-lg), α-caseinate or β-caseinate, showed reinforcement of the starch granule structure by both caseinates, but not by the whey proteins (α-lac and β-lg). Reinforcement was evident from (i) later onset of increase in viscosity on heating; (ii) higher gelatinisation temperature by differential scanning calorimetry; (iii) micrographs showing reduced swelling during heating and in the final pastes obtained on cooling; and (iv) elimination of a characteristic “secondary swelling peak” observed for WMS immediately after completion of heating to 95 °C and attributed to fracture of a restricting layer of lipid and protein at the surface of the granules. A likely mechanism of reinforcement is binding of caseinate to the lipid–protein layer. Images from confocal laser scanning microscopy with fluorescent labelling of protein showed attachment of aggregated β-caseinate to the surface of WMS granules in mixtures that had been heated (under shear) to 70 °C. Corresponding images for mixtures with α-caseinate (which is less aggregated) showed penetration of protein to the interior of the granules, which would allow binding to occur on the inside of the surface layer as well as the outside. The inability of the more hydrophilic whey proteins to reinforce the WMS granules suggests that binding of caseinates to the lipid–protein layer occurs predominantly by hydrophobic association. The understanding that caseinates make gelatinised WMS granules smaller and tougher could be useful in product formulation.     

The adsorption behaviour of faba bean proteins at a sunflower oil-water interface

The present study aims at investigating the absorption behaviour of acetylated (AFBPI) and non-acetylated (FBPI) faba bean protein isolate at a sunflower oil-water interface in dependence on different environmental conditions (protein concentration, pectin addition).     

甜橙全果去皮技术的研究

研究试验了一种新的去除甜橙外果皮并得到全果的方法技术。该技术主要包括两个部分:首先用注水的方法去除鲜果的外果皮;然后再用果胶酶处理的方法脱除全果的外露囊衣,得到色泽鲜艳、风味良好、营养丰富的去皮全果。     

橘皮果醋的研制

采用液体发酵法酿制橘皮果醋,经水解、酒精发酵及醋酸发酵等工序。试验结果表明:酶解后橘皮汁的还原糖含量可达3.8g/100mL,用大米糖浆补糖至7.8g/100mL;经酒精发酵60h,酒精度达5.0°;再经醋酸发酵80h,酸度达3.15g/100mL。产品澄清透明,有柑橘特有的清香,酸味浓郁,醇香不涩。     

橙皮果酱的研制

对橙皮果酱的加工工艺进行研究,生产出了具有浓郁橙子风味、酱体均匀细腻、流散性适宜的优质果酱。     

柑桔类果汁苦味物质的脱除研究

柠碱和柚苷是柑桔汁和柑桔其他制品中的主要苦味成分,采用吸附脱苦法、酶脱苦法、β-环糊精脱苦法、乙烯利代谢脱苦法及其他脱苦法可将它们除去,文中还提出了采用综合脱苦法应用于生产实际的观点。     

低糖凝固型柳橙酸奶的研制

研究了以奶粉和柳橙果肉为原料,并以高倍甜味剂替代大部分蔗糖来生产凝固型酸奶的最佳配方及工艺。通过感官测评确定甜味剂的最佳配方：蔗糖2％,安赛蜜0．015％,三氯蔗糖0．005％;通过正交实验确定奶粉、稳定剂、果肉的用量,并对发酵工艺进行优化,最终获得风味突出、质感细腻的酸奶。     

Immunochemical assays of enzymes in foodstuffs

Abstract

The paper reviews immunochemical methods used in the field of food enzymology. The advantages of immunochemical identification and assessment of enzymes include high specificity and sensitivity, and the possibility of detecting inactivated enzymes. Immunochemical methods have been applied mainly to the investigation of cereal and malt enzymes, the determination of chill‐proofing proteinases and amyloglucosidase in beer, the analysis of combined rennets, and the detection of enzymes of psychrotrophic bacteria in milk as a measure of unfavorable microbial contamination.     

Volatiles of orange juice and orange wines using spontaneous and inoculated fermentations

The effect of spontaneous fermentation and inoculated fermentation on the volatile compounds of orange wine was studied. The differences on volatile compounds of orange juice and orange wine were also observed. The volatile compounds were analyzed by sensory and instrumental analysis. Solid phase microextraction was used for extraction of volatile compounds. Sensory analysis indicated that no significant differences existed on the wine odor between the two methods. A total of 17 and 19 volatile compounds were identified and quantified in spontaneous and inoculated fermentations, respectively. Esters followed by alcohols and terpenes were the most abundant volatile compounds in the two orange wines. Thirteen of these compounds were present both in the two methods. Totally 31 volatile compounds were found in orange juice, and terpenes were quantitatively the dominant group. Esters were found to be the important volatile compounds formed during fermentation, such as isoamyl acetate, ethyl hexanoate, ethyl benzoate, diethyl succinate, ethyl decanoate and ethyl laurate, etc.     

Precipitation behaviour of caseinomacropeptides and their simultaneous determination with whey proteins by RP-HPLC

A reversed-phase high-performance liquid chromatographic (RP-HPLC) method on polyvinylbenzene/divinylbenzene copolymer resin was applied for the quantitative determination of glycosylated and non-glycosylated caseinomacropeptides (CMP), in presence of the major whey proteins (α-lactalbumin and β-lactoglobulin). The peak profile of the CMP-fractions was calibrated using the response factor determined by amino acid analysis. By omitting any critical precipitation step (e.g. trichloroacetic acid, TCA) usually applied to remove whey proteins, the method allows the simultaneous determination of the major whey proteins and CMP—the complete native spectrum—in a single run. As a prerequisite for forthcoming kinetic studies of CMP release, the precipitation sensitivity of individual whey proteins or CMP fractions against TCA or perchloric acid (PCA) was studied systematically. All CMP fractions were partially precipitated even at low TCA concentrations, whereas PCA treatment resulted in negligible decrease of CMP solubility.     

橙汁饮料中橙与橘成分双重实时荧光定量PCR检测技术

目的：建立双重实时荧光定量PCR检测橙汁饮料中橙与橘成分的方法。方法：通过设计和筛选橙、橘成分的引物和探针,检测水果寻找橙和橘的荧光扩增规律,利用橙和橘在FAM/VIC两个荧光通道上的比值差异来判定橙、橘成分。采用模拟橙汁掺杂柑橘汁试验验证方法检测的最低掺杂比例,对市售橙汁饮料进行检验来验证方法可行性。结果：纯橙水果在FAM和VIC两通道均有荧光扩增曲线,FAM/VIC通道荧光比值在0.5±0.2的范围内,而纯橘水果仅在FAM通道有很强的荧光扩增曲线。模拟掺杂试验中,可以检测出橙汁中掺有10%及以上的柑橘汁。结论：该方法能够检测橙汁饮料中的橙和橘成分,可用于市售橙汁饮料的鉴伪。     

桔子酒澄清剂配方优化

采用单一澄清剂明胶、皂土、果胶酶、硅藻土在冷处理（4 ℃）和室温条件下对桔子发酵原酒进行澄清实验。结果表明,不同质量浓度的澄清剂对桔子酒的处理效果均显著,相对于果胶酶、明胶和皂土的澄清效果,硅藻土的澄清效果不好。冷处理的澄清效果优于室温处理。正交试验结果表明,复合澄清剂的澄清效果优于单一澄清剂,在0.8 g/L果胶酶、0.7 g/L明胶和2.5 g/L皂土构成的复合澄清剂在冷处理（4 ℃）下静置48 h,酒体澄清度最好,可达98.0%。澄清后酒体透明清亮,色泽明快,桔子发酵原酒的风味不变。