Comparison between reconstituted and fresh skim milk chemical and electrochemical acidifications

The aim of this study was to compare the electrochemical and chemical acidification of reconstituted and fresh skim milk in terms of electrodialytic parameters, precipitation kinetics, chemical composition and physicochemical and functional properties of isolates produced by bipolar membrane electro acidification (BMEA). The electrodialytic parameters were not influenced by the type of milk when both milks were compared at a similar protein and salt content. The difference in precipitation kinetics observed between the two milks, whatever the acidification procedure, can be explained mainly by a difference in salt content. Isolates produced by BMEA showed similar physicochemical and functional properties (except for foaming capacity) to isolates produced chemically. The main factor affecting the composition and the physicochemical and functional properties was the pre‐treatment of milk prior to acidification: it had a higher impact on the functional properties than the acidification treatment itself. Copyright © 2002 Crown in the right of Canada. Published for SCI by John Wiley & Sons, Ltd     

Effect of added salt and increase in ionic strength on skim milk electroacidification performances

Bipolar-memibrane electroacidification (BMEA) technology which uses the property of bipolar membranes to split water and the demineralization action of cation-exchange membranes (CEM), was tested for the production of acid casein. BMEA has numerous advantages in comparison with conventional isoelectric precipitation processes of proteins used in the dairy industry. BMEA uses electricity to generate the desired ionic species to acidify the treated solutions. The process can be precisely controlled, as electro-acidification rate is regulated by the effective current density in the cell. Water dissociation at the bipolar membrane interface is continuous and avoids local excess of acid. In-situ generation of dangerous chemicals (acids and bases) reduces the risks associated with the handling, transportation, use and elimination of these products. The aim of this study was to evaluate the performance of BMEA in different conditions of added ionic strength (p(added) = 0, 0.25, 0.5 and 1.0 M) and added salt (CaCl2, NaCl and KCl). The combination of KCl and p(added) = 0.5 M gave the best results with a 45% decrease in energy consumption. The increased energy efficiency was the result of a decrease in the anode/cathode voltage difference. This was due to an increase of conductivity, produced by addition of salt, necessary to compensate for the lack of sufficiently mobile ions in the skim milk. However, the addition of salts, irrespective of type or ionic strength, increased the required operation time. The protein profile of isolates were similar under all experimental conditions, except at 1.0 M-CaCl2.     

Study of taste-active compounds in the water-soluble extract of mature Cheddar cheese

The chemical composition of the water-soluble extracts of mature Cheddar cheese were identified, with the emphasis on understanding the interplay of compounds contributing to the savoury taste in Cheddar. The ultra-filtered water-soluble extracts of two mature Cheddar cheeses were fractionated by gel permeation chromatography (GPC). By sensory evaluation, two taste-active GPC fractions were identified from each cheese. On the basis of chemical profiling of these fractions, aqueous model tastant mixtures were prepared and sensory omission tests carried out. Glutamic acid, organic acids and mineral salts were the main tastants, whereas the other amino acids had a limited impact on taste. The characteristic umami taste was explained by a synergistic effect of glutamic acid and salts. Matching umami taste intensities were obtained from different concentrations of glutamic acid and salts. Unmasking of a bitter or sweet taste from mixtures of sub-threshold concentrations of amino acids without glutamic acids was also observed.     

Coagulation and electrocoagulation of wastes polluted with dyes

Dyes are common pollutants in a large variety of industrial wastewaters, and the treatment of these wastes by coagulation has been extensively studied in the literature. This work is focused on the comparison of the efficiencies of the chemical and the electrochemical coagulation processes with hydrolyzing aluminum salts, and it tries to determine the similarities or differences that exist between the two coagulation processes. To do this, Eriochrome Black T solutions were used as a model of dye-polluted wastewater, and experiments of both coagulation technologies were planned to meet the same operation conditions. The pH, the aluminum concentration, the type of electrolyte, and the mode of dosing of aluminum were found to influence the process. Moreover, the speciation of aluminum was found to be the key parameter to explain the results, in terms of the mechanisms previously proposed in the literature for dissolved organic matter coagulation.     

Two by-products of the olive oil extraction industry as oleic acid supplement source for Iberian pigs: effect on the meat's chemical composition and induced lipoperoxidation

BACKGROUND: The objective of the present study was to evaluate the effect of two by‐products of the olive oil extraction industry—olive soapstocks and olive‐pomace oil—as added fat sources into feed concentrates, in two different rearing systems (free‐range complemented with concentrates and intensive rearing with concentrates) on the chemical composition and oxidative stability of Iberian pig meat. RESULTS: No differences in the chemical composition, colour and fatty acid composition of gluteobiceps m. were found due to added fat source. However, the feeding system had a significant effect on protein (P < 0.05), γ‐tocopherol (P < 0.05), colour (P < 0.01) and fatty acid composition of gluteobiceps m. Neither added fat source nor the feeding system had an effect on the malondialdehyde content. CONCLUSION: The addition of olive soapstock or olive‐pomace oil as fat sources into concentrates did not influence meat composition or fatty acid profile. However, there are differences in the fatty acid composition of meat from Iberian pigs as a result of the production system used. Copyright © 2012 Society of Chemical Industry     

Sherry wine vinegar: physicochemical changes during the acetification process

The quality of a wine vinegar is determined by the raw wine substrate and the acetification process employed in its production. Attempts to characterise vinegars have been based on these two features, along with variables such as total extract, glycerol, organic acids, volatile compounds and phenolic composition. When the final products are analysed, it is difficult to evaluate to what extent quality differences are due to the raw material or to differences in production methods, so it is necessary to determine the influence of each feature separately. The present work focuses on monitoring physicochemical changes during the acetification of sherry wine by submerged culture. ANOVA showed significant differences for ethanol, acetic and lactic acids and some volatile compounds (methanol, 1‐propanol, 2‐methyl‐1‐propanol, 2‐methyl‐1‐butanol, 3‐methyl‐1‐butanol, acetoin, acetaldehyde, ethyl acetate and ethyl lactate). However, no statistical changes were found for phenolic compounds during acetification. The phenolic composition of the final product was determined by the substrate employed. In addition, the influence of cycle duration on the chemical composition was studied; the only compound affected by this factor was 2‐methyl‐1‐butanol. © 2001 Society of Chemical Industry     

Invited review: perspectives on the basis of the rheology and texture properties of cheese

Physical and chemical properties of cheese, such as texture, color, melt, and stretch, are primarily determined by the interaction of casein (CN) molecules. This review will discuss CN chemistry, how it is influenced by the cheese-making process, and how it impinges on the final product, cheese. We attempt to demonstrate that the application of principles governing the molecular interactions of CN can be useful in understanding the many physical and chemical properties of cheese and, in turn, how this can be used by the cheesemaker to produce the desired cheese. The physical properties of cheese (as well as flavor) are influenced by a number of factors including: milk composition; milk quality; temperature; the rate and extent of acidification by the starter bacteria; the pH history of cheese; the concentration of Ca salts (proportions of soluble and insoluble forms); extent and type of proteolysis, and other ripening reactions. Our hypothesis is that these factors also control and modify the nature and strength of CN interactions. The approach behind the recently proposed dual-binding model for the structure and stability of CN micelles is used as a framework to understand the physical and chemical properties of cheese.     

两个产地洋葱的UHPLC图谱分析及前列腺素A1含量测定

目的:对不同产地洋葱化学成分含量的差异进行分析评价。方法:以中国南北(云南和黑龙江)两个主产地的洋葱为原料,采用超高效液相色谱(UHPLC),结合多元统计学分析两个产地洋葱化学成分含量差异及特征化学成分前列腺素A1(PGA1)。结果:洋葱UHPLC化学成分含量图谱共标定73个共有色谱峰,通过正交偏最小二乘法,能区别出两个产地洋葱化学成分含量,结合VIP值>1、P<0.05和S-plot分析共筛选出11种主要差异标志物。云南洋葱PGA1含量[(197.21±63.22)mg/kg]显著高于黑龙江洋葱[(121.37±43.12)mg/kg]。结论:云南和黑龙江两个产地洋葱化学成分含量及PGA1含量存在显著差异。     

Cheese‐making capacity of goat's milk during lactation: influence of stage and number of lactations

The effect of the stage and number of lactations on the technological properties and cheese‐making capacity was studied in Murciano‐Granadina goat's milk. Controls were done every month to evaluate the evolution of chemical composition and the values of the clotting properties which define the milk quality with regards to rennet curdling. The influence of the month of kidding was also evaluated. The average composition of the milk in the two kidding periods considered was as follows: fat 5.05% and 5.31%; protein 3.68% and 3.58%; casein 2.80% and 2.66%; lactose 4.71% and 4.68%, and dry matter 14.29% and 14.45%. No significant differences were found in the chemical composition due to the stage and lactation number; however, higher values of the protein fractions were determined in the first kidding period than in the second one. We determined that a higher casein concentration was associated with a lower milk clotting time and higher rate of firmness. We also found a highly significant (P < 0.001) correlation between titration acidity values and casein content (0.551). No significant differences, however, were found in cheese composition between kidding periods. © 1999 Society of Chemical Industry     

Change in surface chemistry of the cuticle of human hair by chemical and photochemical oxidation

This is a multifaceted study on the characterization and quantification of damage to the hair fiber surface caused by photochemical and cosmetic chemical oxidative processes. Unique techniques were used, including a microfluorometric method that had been adapted to characterize and quantify the delipidation and acidification of the human hair surface during light exposure and cosmetic chemical grooming processes such as bleaching. During photochemical and chemical oxidation, breakdown of the lipid domains (also called the F‐layer) of the outer b‐layer occurs on the exposed scale faces and cysteic acid groups are generated on the cuticle cell surface. The newly formed acid functionalities can be tagged with the cationic fluorochrome Rhodamine B, allowing not only quantification of the level of progressive acidification but also localization of the newly formed acid functionalities. On the other hand, the negative charges generated on the hair surface by oxidation can also bind low molecular weight quaternary cationic conditioning compounds such as cetyltrimethylammonium bromide. This process can be considered a relipidation by adsorption. We have shown that the entire process of delipidation/acid formation and subsequent relipidation by adsorption on the scale faces can be quantified by X‐ray photoelectron spectroscopy. Since X‐ray photoelectron spectroscopy analysis is highly sensitive and able to detect atomic species at the very surface of the hair fibers, receiving signals from an escape depth as shallow as 25 Å, it appeared ideal for the characterization of treatment‐induced changes in the hair surface. However, X‐ray photoelectron spectroscopy provides an average elemental composition of the hair surface including scale faces and scale edges. The microfluorometric technique, on the other hand, can distinguish progressive delipidation of the scale faces from changes occurring at the broken scale edges. This distinction was shown and characterized in detail by slow speed microfluorometric scanning of the hair surface. Chemical and photochemical oxidative processes at the hair surface result in certain collateral effects. Particularly changes in surface wettability and fiber friction are of significance to the cosmetic chemist because they affect the spreading and wicking of products in hair as well as the managability and the body of hair assemblies. Methods of characterizing these effects are discussed briefly.     

Effect of cactus pear (Opuntia ficus‐indica (L.) Miller) on the antioxidant capacity of donkey milk

The cladodes of Opuntia ficus‐indica (L.) Miller were fed to lactating donkeys as an alternative food, in order to evaluate effects on the chemical composition and antioxidant activity of their milk. Lactating donkeys were divided into two groups: standard feeding and alternative feeding. With regard to chemical composition, no differences were observed. Total antioxidant capacity was constant in the standard feeding group, while it increased in the alternative feeding group: the radical scavenging activity increased from 95.53% to 96.62% in the ABTS test and from 28.40% to 33.33% in the DPPH test. This indicated that alternative feeding affects the antioxidant capacity of milk.     

Improvement of mead fermentation by honey‐must supplementation

Through honey's fermentation, diverse beverages can be obtained, among which is mead, an alcoholic drink with 8 to 18% of ethanol (v/v). Since honey is a matrix with a low nutrient concentration and other unfavourable growth conditions, several problems are usually encountered, namely delayed or arrested fermentations, unsatisfactory quality parameters and lack of uniformity of the final product, as well as unpleasant sensory properties. In this context, the aim of this work was to optimize mead production through honey‐must supplementation with (a) salts, (b) vitamins or (c) salts + vitamins. The effects of the honey‐must formulation on the fermentation kinetics, growth profile and physicochemical characteristics of final meads were evaluated. The results showed minor differences in the fermentation profile and time between fermentations with the different formulations. The growth profile was influenced more by the yeast strain than by the supplements added to the honey‐must. In general, the honey‐must composition did not influence meads’ final characteristics, except regarding the SO₂ concentration of the meads produced using the strain QA23. In summary, the addition of salts and/or vitamins to honey‐must had no positive effects on the fermentation, growth profile or characteristics of the final products. Copyright © 2015 The Institute of Brewing & Distilling     

Acidification kinetics,physicochemical properties and sensory attributes of yoghurts prepared from mixtures of goat and buffalo milks

Five formulations of set‐type yoghurt were produced using different caprine–bubaline milk ratios. They were investigated in regard to the acidification kinetics, yoghurt composition, rheology and sensory attributes. The acidification profile of all five experimental groups was similar, but the maximum acidification rate was higher for yoghurts of milk mixtures. The addition of buffalo milk increased total solids, fat and overall acceptance of yoghurt, besides decreasing synaeresis. Yoghurts made from caprine–bubaline milk mixtures reached good sensory scores and yoghurt prepared with 30% of goat milk and 70% of bubaline milk received the best sensory scores.     

Characterization and Quantitation of Triterpenoid Saponins in Raw and Sprouted Chenopodium berlandieri spp. (Huauzontle) Grains Subjected to Germination with or without Selenium Stress Conditions

Pseudocereal Chenopodium berlandieri spp. (huauzontle) was evaluated to determine saponin composition. Saponins were evaluated in raw and germinated grains subjected to chemical stress induced by sodium selenite. Analysis by liquid chromatography coupled with ELSD detector revealed the presence of 12 saponins, identified according to compounds previously assayed in Chenopodium quinoa. Saponins found at the highest concentrations in raw grains were derived from oleanolic and phytolaccagenic acids. Total saponin concentration significantly decreased in germinated compared to raw grains due to the significant loss of 90.1% and 95.7% of the phytolaccagenic acid without and with chemical selenium stress, respectively. The most abundant saponin in germinated sprouts decreased during normal germination. Interestingly, the concentration of this particular saponin significantly increased during the Se‐induced stress germination. Chemical stress with selenium salts proved to change the saponin composition in geminated Chenopodium berlandieri spp. grains, therefore affecting their potential use as ingredient in the food industry.     

滞头废水的预处理试验

通过采用酸析法和化学混凝法对滞头废水进行预处理,其中化学混凝法选择聚合氯化铝(PAC)作为混凝剂.试验结果表明:在单独采用酸析法对CODcr去除和蛋白质回收不理想的情况下,采用酸析-离心方法,CODcr去除率为68.2%,蛋白质回收率为64.3%;采用化学混凝法,CODcr去除率为73.7%,蛋白质回收率69.8%.通过对滞头废水进行预处理,不仅能有效回收滞头废水中的蛋白质,而且能大幅降低污染负荷.     

Physical and sensory properties of regional sea salts

Seven varieties of sea salt and a Kosher control were characterized by composition, various physical properties and rates of dissolution in artificial saliva. These measures were compared to sensory time–intensity data in which the temporal profile of salt taste of the sea salt crystals was measured by a trained panel (n = 12). Salts contained either the same or less sodium than the Kosher salt. Three salts contained similar sodium contents as the Kosher control while True Kona contained the lowest sodium content with 16.75% less sodium than Kosher salt. Significant differences were observed among salts for their rates of dissolution, temporal perception of salt taste as well as composition. From a sensory perspective, there were few differences in maximum salt taste intensity. There were, however, some differences in the salts' time–intensity profiles. Red Aelea exhibited the lowest maximum intensity but also exhibited the longest duration of salt taste intensity in comparison to all other salts. Rates of dissolution were found to be negatively correlated with time to maximum salt taste intensity and overall duration of salt taste. Significant differences were found between the size of the salt particles and size was strongly correlated with rates of in-vitro dissolution as well as with a variety of time–intensity sensory measures Based on the fact that salts did not show large differences is taste intensity and many of the salts did not contain less sodium than the Kosher control, using the studied sea salts as a sodium reduction strategy is not viable.     

Antioxidant activity of essential oil of oregano species from Argentina in relation to their chemical composition

The purpose of this work was to determine chemical composition and antioxidant activity of essential oil of different oregano species from Argentina: ‘Cordobes’, ‘Criollo’, ‘Mendocino’ and ‘Compacto’. The essential oil composition was determined by gas–liquid chromatography and mass spectrometry. Scavenging activity was analysed by DPPH test. The antioxidant activity of the essential oils was determined by an accelerated oxidation test in canola oil. Thirty‐nine compounds were identified in the oregano essential oils. The oregano species showed differences in their chemical composition, radical scavenging activity and antioxidant activity. The main compounds in the studied oregano species were thymol and trans‐sabinene hydrate followed by γ‐terpinene, terpinen‐4‐ol and α‐terpinene. The oregano, ‘Criollo’, was rich in γ‐terpinene and had lower thymol and trans‐sabinene hydrate and higher α‐terpinene and carvacrol contents than the other oregano species. ‘Mendocino’ had higher trans‐sabinene hydrate and limonene than the other oregano species. ‘Cordobes’ and ‘Compacto’ had higher thymol content, radical scavenging activity and antioxidant activity in canola oil.