Recent applications of high pressure liquid chromatography* to food analysis

Real wine or not? Protecting wine with traceability and authenticity for consumers: chemical and technical basis, technique applications, challenge, and perspectives

Wine is a high-value alcoholic beverage welcomed by consumers because of its flavor and nutritional value. The key information on wine bottle label is the basis of consumers' choice, which also becomes a target for manufacturers to adulterate, including geographical origin, grape variety and vintage. With the improvement of wine adulteration technology, modern technological means are needed to solve the above mentioned problems. The chemical basis of wine determines the type of technique used. Detection technology can be subdivided into four groups: mass spectrometry techniques, spectroscopic techniques, chromatography techniques, and other techniques. Multivariate statistical analysis of the data was performed by means of chemometrics methods. This paper outlines a series of procedures for wine classification and identification, and classified the analytical techniques and data processing methods used in recent years with listing their principles, advantages and disadvantages to help wine researchers choose appropriate methods to meet the challenge and ensure wine traceability and authenticity.

Characterization of acid-extracted pectin-enriched products obtained from red beet (Beta vulgaris L. var. conditiva) and butternut (Cucurbita moschata Duch ex Poiret)

Chemical and rheological characteristics of fractions enriched in soluble dietary fiber are reported. These fractions were obtained through acid hydrolysis of butternut (Cucurbita moschata Duch ex Poiret) and red beet (Beta vulgaris L. var. conditiva) cell wall enriched powders. Hydrolysis was performed using citric acid at different pH values and reaction times (2 and 3 h). Yields obtained for butternut fractions were between 21 and 28 g/100 g; for red beet, yields were 24 and 31 g/100 g for pH 1.5 and 11 and 17 g/100 g for pH 2.0 for previously mentioned times; in general, the increase of the yield was directly correlated with the decrease of pH and the increase of reaction time. Products enriched in low methoxyl pectins were obtained in all cases. At the lowest pH assayed, pectins were essentially constituted by homogalacturonan; a significant content of neutral sugars was determined at the higher extraction pH. Neutral sugars were constituted mainly by arabinose, galactose, rhamnose, and glucose in different proportions for each fraction; in general, butternut fractions showed high glucose contents. Flow behavior for 2.00% (w/v) aqueous systems of the different products was evaluated. Data obtained for fractions isolated at pH 1.5 fit to Herschel-Bulkley and Cross models while those isolated at pH 2.0 fit to Ostwald and Cross models. All samples showed low viscosity and, hence, poor thickening properties.

The chemistry behind redox regulation with a focus on sulphur redox systems

Sulphur metabolism in plants provides a wealth of natural products, including several chemically unusual substances, such as thiosulphinates, polysulphides and isothiocyanates. Many of these reactive sulphur species (RSS) exhibit a distinct redox behaviour in vitro, which translates into a rather interesting biological activity in vivo, such as antibiotic, fungicidal, pesticidal or anticancer activity. While the molecular basis for such activity has long remained obscure, research into sulphur-based redox systems during the past 5-10 years has achieved a better knowledge of the in vitro properties of RSS and has led to an improved understanding of their impact on intracellular redox signalling and control pathways in living cells. It has become apparent that the redox chameleon sulphur occurs in biological systems in about 10 different oxidation states, which give rise to an extensive and complicated network of sulphur-based redox events. Together, natural sulphur products from plants and their intracellular targets provide the basis for innovative design of novel antibiotics, fungicides, pesticides and anticancer agents.

Lipid oxidation on foods

This review discusses the basic chemical reactions that affect food flavor quality. Although there are many reactions that can lead to the deterioration of quality in foods, this review focuses on lipid oxidation and how it adversely affects flavor principals. It also presents technological advances for studying the basic mechanism of lipid oxidation, for measuring its intensity, and for retaining food quality. The food commodities that provide the subject matter for this review include vegetable oils, legumes, cereal grains, eggs, beef, lamb, poultry, seafoods, and catfish. The methodologies for assessing food quality form a multidisciplinary approach that includes primarily instrumental analysis by direct gas chromatography, chemical analysis by the TBA test, and sensory analysis by quantitative descriptive determinations. The author hopes that the information presented in this review is applicable to food commodities not discussed.

Routine high-performance liquid chromatographic determination of carboxylic acids in wines and champagne

Carboxylic acids have an important influence on the biological stability and the organoleptic properties of wines. A simple, rapid and reproducible high-performance liquid chromatographic method for the determination of the main carboxylic acids (tartaric, malic, shikimic, lactic, acetic, citric, succinic, fumaric and propionic acids) in wines is described. There is no interference from either sugars or amino acids. The method does not need any preparation or extraction of the sample. The linearity, the level of detection, the repeatability and the reproducibility were studied for each acid. The results are compared with those obtained by chemical and enzymatic assays.