Proteolytic processing of the peanut allergen Ara h 3

The allergen Ara h 3 has been purified recently from peanuts. In contrast to recombinant Ara h 3, a 60 kDa single-chain polypeptide, the allergen isolated from its native source is extensively proteolytically processed. The characteristic proteolytic processing for 11S plant storage proteins of the glycinin family is observed for Ara h 3 yielding an acidic and a basic subunit, bound by a disulfide bridge. In addition to this, proteolytic truncation is observed for the acidic subunit but not for the basic subunit of Ara h 3. A series of Ara h 3 polypeptides ranging from 13-45 kDa was separated by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and each band was digested by trypsin. Peptides related to the bands were identified and a scheme positioning the different polypeptides in the Ara h 3 sequence has been constructed. Peptide analysis showed sequence heterogeneity at two positions indicating the presence of multiple genes encoding variant, but highly homologous Ara h 3 proteins. The pool of Ara h 3 polypeptides from its native source illustrated that allergen from the peanut is much more complex than the recombinant protein used for epitope mapping experiments. From several Ara h 3 truncation products one or more immunoglobulin E (IgE) binding sites had been removed. Characterization of the allergenicity of Ara h 3 should therefore also include IgE-binding studies with peanut-derived Ara h 3, providing the high degree of variation in the Ara h 3 protein structure, as this is what peanut-allergic individuals are confronted with.     

Demineralization of animal blood plasma by ion exchange and ultrafiltration

The blood waste from slaughterhouses is strictly controlled due to its high pollutant load, the treatment for its purification being of great economic interest. The separation of proteins, the most valuable components of blood, in a chromatographic column requires the use of well treated plasma, in particular the removal of inorganic salts. Accordingly, a demineralization process is usually required. In this paper, ion exchange and ultrafiltration demineralization techniques were tested and the results compared. In the ion exchange experiments, the blood plasma was treated with cationic and anionic resins in packed columns, studying the removal of the major cations and anions, protein loss and pH evolution in both the loading and elution steps. In the demineralization process by means of membranes, a 10KDa ultrafiltration membrane was used, the blood plasma being filtered to concentrate all the proteins in the retentate while removing the inorganic ions and other compounds in the permeate. The evolution of the major anions and cations in the plasma and the protein loss were studied at different volumetric concentration factors. The results obtained enable us to draw conclusions as regards the advantages and disadvantages of each technique at a laboratory scale and to offer some considerations regarding the operation at an industrial scale.     

Microstructure alterations in beef intramuscular connective tissue caused by hydrodynamic pressure processing

Scanning electron microscopy (SEM) was utilized to evaluate microstructural changes in intramuscular connective tissue of beef semimembranosus muscle subjected to hydrodynamic pressure processing (HDP). Samples were HDP treated in a plastic container (HDP-PC) or a steel commercial unit (HDP-CU). Control and HDP samples were obtained immediately post-treatment and after 14 days of aging for SEM and Warner–Bratzler shear force (WBSF) analysis. Immediately post-treatment, HDP treated samples exhibited lower (P < 0.01) WBSF than did controls. After aging, HDP-PC samples had lower (P < 0.01) WBSF than that of aged controls. SEM analysis indicated that HDP-PC treatment disrupted the integrity of the collagen fibril network of the endomysium in both the non-aged and aged samples. Aging effects on the intramuscular connective tissue were observed in the HDP-PC and control samples. Both WBSF and connective tissue changes were greater in the HDP-PC than in the HDP-CU treated samples. Data suggest that shockwave alterations to connective tissue contribute to the meat tenderization of HDP.     

A new hydroxytyrosol metabolite identified in human plasma: Hydroxytyrosol acetate sulphate

We report progress in the study of olive oil phenolic metabolites in humans and identify a new hydroxytyrosol metabolite called hydroxytyrosol acetate sulphate, which was determined using tandem MS, after ingestion of 30 ml of olive oil with a high phenolic content (500 mg/kg oil), reaching a maximum concentration of 1.63 μM. In order to understand and explain the generation of this metabolite, two different pathways are proposed.     

Control of disinfection by-products in canned vegetables caused by water used in their processing

ABSTRACT

Canned vegetables come into contact with sanitizers and/or treated water in industry during several steps (namely washing, sanitising, blanching and filling with sauces or brine solutions) and therefore they can contain disinfection by-products – DBPs). This study focused on the occurrence of trihalomethanes (THMs) and haloacetic acids (HAAs) in a wide variety of canned vegetables (75 samples). For each vegetable, the edible solid and liquid phases of the package were separated and analysed individually. DBPs can be present in both solid (up to eight species) and liquid (up to 11 species) phases, their levels being higher in liquid ones. Volatile THMs predominate in the edible solid phase (up to four species), while HAAs do so in the liquid phase (up to five species) according to their ionic and non-volatile nature. The lowest concentrations of DBPs were found in tomatoes because they were often preserved in their own juice, without water.     

Estimating volume and mass of citrus fruits by image processing technique

An image processing based technique was developed to measure volume and mass of citrus fruits such as lemons, limes, oranges, and tangerines. The technique uses two cameras to give perpendicular views of the fruit. An efficient algorithm was designed and implemented in Visual Basic (VB) language. The product volume was calculated by dividing the fruit image into a number of elementary elliptical frustums. The volume is calculated as the sum of the volumes of individual frustums using VB. The volumes computed showed good agreement with the actual volumes determined by water displacement method. The coefficient of determination (R²) for lemon, lime, orange, and tangerine were 0.962, 0.970, 0.985, and 0.959, respectively. The Bland–Altman 95% limits of agreement for comparison of volumes with the two methods were (−1.62; 1.74), (−7.20; 7.57), (−6.54; 6.84), and (−4.83; 6.15), respectively. The results indicated citrus fruit’s size has no effect on the accuracy of computed volume. The characterization results for various citrus fruits showed that the volume and mass are highly correlated. Hence, a simple procedure based on computed volume of assumed ellipsoidal shape was also proposed for estimating mass of citrus fruits. This information can be used to design and develop sizing systems.     

The effect of sample grinding procedures after processing on gas production profiles and end‐product formation in expander processed barley and peas

Grinding is a technological process widely applied in the feed manufacturing industry and is a prerequisite for obtaining representative samples for laboratory procedures (e.g. gas production analysis). When feeds are subjected to technological processes other than grinding (e.g. expander treatment), grinding afterwards may disturb the effect of processing, both in practice and when laboratory techniques are applied. Therefore, this study aimed to establish the possible effects of different grinding procedures and sample preparation on the degradative behaviour of expander processed barley and peas. Samples of expander processed barley and peas were subjected to six different sample preparation procedures (intact sample, dissolved sample, samples ground stepwise over 6 and 3 mm sieves, samples ground stepwise over 6, 3 and 1 mm sieves, samples ground over a 3 mm sieve and samples ground over a 1 mm sieve). The patterns of gas production in these samples were studied over a period of 72 h incubation using an automated in vitro gas production system. The particle size distribution determined by dry sieve analysis and the Coulter counter method changed due to the different grinding procedures. Grinding the samples of expander processed barley and peas changed the kinetics of gas production and led to a faster degradation, most pronounced after stepwise grinding. However, the formation of the fermentation end‐product was not affected by the method of sample preparation. In expander processed barley, the difference in the degradation pattern due to the different grinding procedures was small. Copyright © 2007 Society of Chemical Industry     

高效液相色谱-电感耦合等离子体质谱法测定栉孔扇贝中6种砷形态化合物

目的建立高效液相色谱-电感耦合等离子体质谱法(highperformanceliquid chromatography-inductively coupled plasma mass spectrometry, HPLC-ICP-MS)定量测定栉孔扇贝中6种砷形态的方法。方法称取均质后的样品1.0 g置于50 mL离心管中,加入5 mmol/L(NH4)2CO3溶液20 mL,混匀,超声提取30 min,经0.45μm滤膜过滤。采用DionexIonPac AS-7(250 mm×4.0 mm, 10μm)色谱柱分离,流动相为5 mmol/L(NH4)2CO3溶液和200 mmol/L(NH4)2CO3溶液,然后ICP-MS测定栉孔扇贝中的6种砷形态。结果市售栉孔扇贝中总砷含量高,64.8%～86.0%砷元素是以无毒砷甜菜碱的形式存在,无机砷含量低于国标限量要求。在优化实验条件下,6种砷形态质量浓度在0～100μg/L范围内线性良好,检出限(3S/N)在0.0002～0.0005 mg/kg之间,定量限在0.001～0.002 mg/kg之间,加标回收率在80.0%～100.4%之间, RSD在2.02%～5.78%之间。结论该方法快速、准确、灵敏,适合测定栉孔扇贝中的主要砷形态化合物。     

Evaluation of the quality of olive oil using fatty acid profiles by direct infusion electrospray ionization mass spectrometry

Electrospray ionization mass spectrometry is used to predict the olive oil quality according to European Union marketing standards. Samples were 1:50 diluted in an alkaline 85:15 (v/v) propanol/methanol mixture and directly infused into the electrospray ionization source of an ion trap mass spectrometer. The establishment of ratios of the peak abundances of the free fatty acids followed by linear discriminant analysis was employed to predict the olive oil quality grade. In addition, using multiple linear regression and partial least-squares regression, the percentages of extra virgin and virgin olive oils in binary mixtures were predicted with 5–11% average prediction errors.     

Prediction of the genetic variety of Spanish extra virgin olive oils using fatty acid and phenolic compound profiles established by direct infusion mass spectrometry

The genetic varieties of Spanish extra virgin olive oils (Arbequina, Hojiblanca and Picual) were predicted by direct infusion of the samples in the electrospray ionization source of a mass spectrometer, followed by linear discriminant analysis of the spectral data. The samples were 1:50 diluted (v/v) with an 85:15 propanol/methanol (v/v) mixture containing 40 mM KOH and infused. The abundances of the [M–H]⁻ peaks of the free fatty acids (7 peaks) and 28 phenolic compounds (20 peaks) were measured. Ratios of pairs of peak abundances were used as predictors in the construction of the linear discriminant analysis models. An excellent resolution between the three genetic varieties was achieved.     

Studies on structures and activities of initial Maillard reaction products by electrospray ionisation mass spectrometry combined with liquid chromatography in processing of red ginseng

Electrospray ionisation-mass spectrometry (ESI-MS) was applied to analyse the water-soluble extract of red ginseng (RG). Several new compounds were produced from the Maillard reaction during the steaming and drying process for preparing RG. Both the tandem electrospray ionisation (ESI-MS(n)) and Fourier transform ion cyclotron resonant mass spectrometric (FT-ICR-MS) data of these products proved that they were the initial Maillard reaction products (MRPs) of maltose with glutamic acid/aspartic acid, which were specific components in RG. In addition, their anti-diabetic and antioxidant activities were examined in vitro. The anti-diabetic activities were evaluated by studying the α-glucosidase inhibition using ultrafiltration LC-MS/MS techniques, while the antioxidant activities were investigated by UPLC-ESI-MS method. The results demonstrated that four initial MRPs in RG were identified as α-glucosidase inhibitors, and showed marked scavenging effect on the hydroxyl radical ((·)OH). Based on these studies, the processing method of RG was improved to generate more active compounds.     

Prediction of the processing factor for pesticides in apple juice by principal component analysis and multiple linear regression

The main objective of this work was to establish a mathematical function that correlates pesticide residue levels in apple juice with the levels of the pesticides applied on the raw fruit, taking into account some of their physicochemical properties such as water solubility, the octanol/water partition coefficient, the organic carbon partition coefficient, vapour pressure and density. A mixture of 12 pesticides was applied to an apple tree; apples were collected after 10 days of application. After harvest, apples were treated with a mixture of three post-harvest pesticides and the fruits were then processed in order to obtain apple juice following a routine industrial process. The pesticide residue levels in the apple samples were analysed using two multi-residue methods based on LC-MS/MS and GC-MS/MS. The concentration of pesticides was determined in samples derived from the different steps of processing. The processing factors (the coefficient between residue level in the processed commodity and the residue level in the commodity to be processed) obtained for the full juicing process were found to vary among the different pesticides studied. In order to investigate the relationships between the levels of pesticide residue found in apple juice samples and their physicochemical properties, principal component analysis (PCA) was performed using two sets of samples (one of them using experimental data obtained in this work and the other including the data taken from the literature). In both cases the correlation was found between processing factors of pesticides in the apple juice and the negative logarithms (base 10) of the water solubility, octanol/water partition coefficient and organic carbon partition coefficient. The linear correlation between these physicochemical properties and the processing factor were established using a multiple linear regression technique.     

Effect of thermal processing on phenolic profiles and antioxidant activities in Castanea mollissima

The effect of three domestic thermal processing methods on chestnut fruit was analysed in this study. By evaluating the changes of the contents of free and bound phenolic profiles as well as the antioxidant activity in chestnut fruit, our study indicated that steaming could better preserve and enhance the level of phenolics and flavonoids in chestnut fruit and thus brought to a higher antioxidant activity. Microwaving could increase the phenolic content and the antioxidant activity of chestnut fruits within a short time, while blanching caused a decrease of flavonoid contents. In addition, our research suggested that there was formation of new phenolics in chestnut fruit, which were discovered during thermal processing because of the increases of bound phenolics after processing. Therefore, the potential of chestnut fruits to be developed as a kind of functional food could be highly expected.     

Classification of ‘Chemlali’ accessions according to the geographical area using chemometric methods of phenolic profiles analysed by HPLC-ESI-TOF-MS

The present work describes a classification method of Tunisian ‘Chemlali’ olive oils based on their phenolic composition and geographical area. For this purpose, the data obtained by HPLC-ESI-TOF-MS from 13 samples of extra virgin olive oils, obtained from different production area throughout the country, were used for this study focusing in 23 phenolics compounds detected. The quantitative results showed a significant variability among the analysed oil samples. Factor analysis method using principal component was applied to the data in order to reduce the number of factors which explain the variability of the selected compounds. The data matrix constructed was subjected to a canonical discriminant analysis (CDA) in order to classify the oil samples. These results showed that 100% of cross-validated original group cases were correctly classified, which proves the usefulness of the selected variables.     

燕麦加工中苦味物质的分离与初步鉴定

目的通过极性分离与感官评价相结合的方法,采用高效液相色谱-四极杆飞行时间质谱(高分辨率液相色谱质谱)联用方法对燕麦加工中的苦味物质进行初步鉴定。方法燕麦样品经过正己烷、75%甲醇萃取,经固相萃取柱净化,经半制备液相色谱富集,利用高分辨率液相色谱质谱技术鉴定。结果 5类苦味物质的可能分子式有C_(27)H_(16)N_2O_4、C_(23)H_(42)N_3O_(14)、C_(24)H_(30)N_(2O)、C_(19)H_(30)N_(4O)、C_(45)H_(64)O_4、C_(22)H_(32)N_2O、C_(17)H_(37)N_(12)O、C_(35)H_(33)N_4O_(14)以及C_(25)H_(38)N_4O_(13)。结论本研究初步鉴定出5类苦味物质的可能分子式,为后续结构鉴定奠定基础。     

等离子体质谱法测定高钠食品中微量铅的应用研究

高钠食品中微量铅用传统的石墨炉原子吸收光谱法直接测定时,样品中大量钠会对铅的信号产生很大的光谱干扰,导致测定结果偏低,没有简便易行的方法去除钠的基体干扰.经微波消解处理过的溶液可以直接用电感耦合等离子体质谱测定铅的含量,经验证该方法操作简便、结果准确、精密度高、检出限低,是测定高盐食品中微量铅的理想方法.     

降低小麦致敏性的食品加工研究进展

小麦是人类的主要食物之一,但同时也是一种主要的食物过敏原,可以引发多种过敏性疾病。目前,降低小麦粉致敏性的加工包括热加工和非热加工处理两大类。其中,热加工处理有高压灭菌和烘焙处理,非热加工处理包括静态超高压、脉冲紫外光、酶法改性、梯度抛光、酸解以及γ辐射处理。在各类加工方法中,高压灭菌、脉冲紫外光、酶法改性、梯度抛光、酸解和γ辐射均能很好地降低小麦的致敏性,显示了广阔的应用前景。但是,制备低致敏性小麦制品的技术仍然匮乏,值得高度关注。      

Identification of isomers and determination of octenylsuccinate in modified starch by HPLC and mass spectrometry

A high performance liquid chromatographic (HPLC) analysis of octenylsuccinic anhydride (OSA) reagent and its bound and un-reacted forms in modified starch was developed. The HPLC system consisted of a C(18) column, an elution system of acetonitrile and water containing 0.1% TFA (45:55, v/v), and a diode array detector (DAD). Using the combination of HPLC-DAD and HPLC-APCI (atmospheric pressure chemical ionisation)-MS (mass spectrometry), four main and two minor peaks were identified as 1-OS acid, cis-2-OS acid, trans-2-OS acid, 1-OSA, cis-2-OSA and trans-2-OSA, respectively. Both free and bound OS content in modified starch were successfully determined by HPLC, and direct measurement of composition of OS was achieved.