Thiolysis-HPLC analysis of proanthocyanidins in health foods and their materials

Abstract

Proantocyanidins (PCs) found in plant products, are reported to be beneficial to human health. A thiolysis-HPLC method was developed to determine PC in health foods and the basic PC material, grape seed extract (GSE). PCs were quantitatively resolved by acid-catalysis in the presence of benzyl mercaptan as nucleophiles. The reaction solutions of actual purchased products were injected into an HPLC and the gallic acid (GA), catechin (CT), epicatechin (EC), epicatechin gallate (ECG), epicatechin benzyl sulfide (EC-S), and epicatechin gallate benzyl sulfide (ECG-S) were separated and detected. The HPLC was performed on a Hypersil BDS C 18 (4.6 mm id  250 mm, 5 μm) column at 35°C, formic acid (0.05%) was employed as mobile phase A, and methanol ∶ acetonitrile = 1∶2 (v/v) was employed as mobile phase B. The flow rate of gradient elution was 0.8 mL$min -1 , and the DAD detection was carried out at 280 nm. The relative standard deviation of CA, CT, EC, ECG, EGS and ECG-S followed by repeated reactions and injections were between 0.4%-4.2%, and the PC levels in six health foods were between 6.9-161.3 mg$g -1 with the mean degree of polymerization (mDP) 2.2-4.2. In a GSE product, the PC content was 531.4 mg$g -1 , and the mDP was 9.0, which although higher than other products tested, was far below the labeled, claimed, concentration. Data showed this method to be accurate and sensitive and can be used for the quality evaluation of actual health products containing PC components.

Research on the Relationship between Freshness and Dielectric Spectrum of Postharvest Ling-Wu Long Jujubes

“…Polarization phenomenon often occurs when biological tissues are placed in an alternating electromagnetic field. Because the macromolecules of biological tissues need a period of time for changing from non-polarization status into polarization status during the polarization process, there is a relaxation time, and the reciprocal of the relaxation time is the characteristic frequency (Li et al,2010) [14]. The sudden decrease of the polarization degree of the Ling-Wu long jujubes caused a sudden decrease of ε ′ , and at the same time a big peak of the ε ′ ′ value occurred.…”

The Core Values of the Brand of Chinese Health Food

“…Enterprises should increase investment in science and technology, follow the advanced science and technology of world closely, digest and absorb in time, otherwise it is impossible to make a brand new development with a low level, wandering and original standard only. High-tech is a key for enterprise to develop new products, improve quality and reduce cost [5]. To build a brand, we must upgrade the products constantly, make new products continue to emerge, to maintain the charm of contemporary quality, to meet various needs of different users.…”