This study presents a review of the Folin-Ciocalteu (F-C) assay for total phenolic content (TPC) determinations and describes different approaches to improve its specificity. Phenolics are regarded as the molecules with the highest potential to neutralize free radicals. Therefore, their quantification is a common practice in different areas of food research. However, when determining TPC in plant food extracts, the presence of reducing interferants [ascorbic acid (AA)] produces inaccurate estimations of TPC values. Different methodologies have been proposed to improve the specificity of the F-C assay. These methodologies include: (i) the use of solid phase extraction (SPE) cartridges to separate interferants from phenolics; (ii) the calculation of a corrected TPC value based on the AA reducing activity present in the extract; and (iii) the pre-treatment of extracts with oxidative agents prior to TPC quantification. These methods are described in detail in the present study. Likewise, their advantages and disadvantages are discussed based on new experimental data. A simple modification of the F-C assay procedure is proposed to quantify both the TPC value and the AA reducing activity in plant food extracts. Values obtained by the modified F-C assay can be used to estimate a corrected TPC value. Folin-Ciocalteu (F-C) assay background and theoryThe F-C assay 16 was generated in order to improve the Folin and Denis (F-D) assay, 17 which was designed to indirectly determine

The development of recovery processes using aqueous two-phase systems (ATPS) has been limited by the extensive experimental work required to establish the optimal system parameters to ensure selective partitioning of the product of interest. Although using full factorial experiments has been demonstrated to be an effective strategy for the characterization of the partitioning behaviour of biological products in ATPS, this approach is characterized by its costly and time consuming nature. As an alternative, the use of a robotic-aided strategy has been proposed. However, the need for high cost equipment may limit the generic implementation of this strategy. Based on practical experience using ATPS, practical strategies for the predictive design of primary recovery processes using polymer-salt systems were derived. To evaluate the generic application of the proposed strategies, four experimental models (B-phycoerythrin, C-phycocyanin, double layered rotavirus-like particles and lutein) were selected. The application of these strategies resulted in the development of simplified recovery processes for the selected experimental models. The practical review presented is considered a relevant contribution that will provide general rules to facilitate the establishment of ATPS processes, particularly for new researchers in the field.

The application of postharvest abiotic stresses is an effective strategy to activate the primary and secondary metabolism of plants inducing the accumulation of antioxidant phenolic compounds. In the present study, the effect of water stress applied alone and in combination with wounding stress on the activation of primary (shikimic acid) and secondary (phenylpropanoid) metabolic pathways related with the accumulation of phenolic compound in plants was evaluated. Carrot (Daucus carota) was used as model system for this study, and the effect of abiotic stresses was evaluated at the gene expression level and on the accumulation of metabolites. As control of the study, whole carrots were stored under the same conditions. Results demonstrated that water stress activated the primary and secondary metabolism of carrots, favoring the lignification process. Likewise, wounding stress induced higher activation of the primary and secondary metabolism of carrots as compared to water stress alone, leading to higher accumulation of shikimic acid, phenolic compounds, and lignin. Additional water stress applied on wounded carrots exerted a synergistic effect on the wound-response at the gene expression level. For instance, when wounded carrots were treated with water stress, the tissue showed 20- and 14-fold increases in the relative expression of 3-deoxy-D-arabino-heptulosanate synthase and phenylalanine ammonia-lyase genes, respectively. However, since lignification was increased, lower accumulation of phenolic compounds was detected. Indicatively, at 48 h of storage, wounded carrots treated with water stress showed ~31% lower levels of phenolic compounds and ~23% higher lignin content as compared with wounded controls. In the present study, it was demonstrated that water stress is one of the pivotal mechanism of the wound-response in carrot. Results allowed the elucidation of strategies to induce the accumulation of specific primary or secondary metabolites when plants are treated with water stress alone or when additional water stress is applied on wounded tissue. If the accumulation of a specific primary or secondary metabolite were desirable, it would be recommended to apply both stresses to accelerate their biosynthesis. However, strategies such as the use of enzymatic inhibitors to block the carbon flux and enhance the accumulation of specific compounds should be designed.

Broccoli sprouts contain health-promoting phytochemicals that can be enhanced by applying ultraviolet light (UV) or phytohormones. The separate and combined effects of methyl jasmonate (MJ), UVA, or UVB lights on glucosinolate, phenolic, carotenoid, and chlorophyll profiles were assessed in broccoli sprouts. Seven-day-old broccoli sprouts were exposed to UVA (9.47 W/m2) or UVB (7.16 W/m2) radiation for 120 min alone or in combination with a 25 µM MJ solution, also applied to sprouts without UV supplementation. UVA + MJ and UVB + MJ treatments increased the total glucosinolate content by ~154% and ~148%, respectively. MJ induced the biosynthesis of indole glucosinolates, especially neoglucobrassicin (~538%), showing a synergistic effect with UVA stress. UVB increased the content of aliphatic and indole glucosinolates, such as glucoraphanin (~78%) and 4-methoxy-glucobrassicin (~177%). UVA increased several phenolics such as gallic acid (~57%) and a kaempferol glucoside (~25.4%). MJ treatment decreased most phenolic levels but greatly induced accumulation of 5-sinapoylquinic acid (~239%). MJ treatments also reduced carotenoid and chlorophyll content, while UVA increased lutein (~23%), chlorophyll b (~31%), neoxanthin (~34%), and chlorophyll a (~67%). Results indicated that UV- and/or MJ-treated broccoli sprouts redirect the carbon flux to the biosynthesis of specific glucosinolates, phenolics, carotenoids, and chlorophylls depending on the type of stress applied.

Aqueous Two-Phase Systems (ATPS) is a primary recovery technique that has shown great potential for the efficient extraction and purification of high value biological compounds. The main advantages of this technique include scaling up feasibility, process integration capability and biocompatibility. In this review, the efficient use of ATPS for the extraction of proteins, genetic material, low molecular weight compounds, bioparticles, nanoparticles and cells is highlighted. The important role of ATPS in process integration, i.e., extractive conversion, extractive fermentation, cell disruption integrated with product recovery, and extractive purification, is discussed. A novel approach to protein molecular characterization combining ATPS and 2-dimension electrophoresis (2-DE) is introduced as a first step in the process development. Novel approaches for downstream processing using ATPS and dielectrophoresis are presented. Finally, trends concerning the application of ATPS strategies to address the future challenges of bioseparation are discussed.

No abstract

The last decade has seen an increasing trend in consumer preference of bottled water over tap water. Little is known what type of water children and adolescents prefer for drinking and what their parents think of their community tap water. The study objective was to assess drinking water preferences, perceptions of the qualities of tap water and bottled water, and fluoride knowledge in an urban pediatric population. We conducted an anonymous survey of a convenience sample of caretakers of children and adolescents at an urban clinic regarding their preferences for tap or bottled water, their perceptions of the quality of tap and bottled water and their knowledge of fluoride. Of the 208 participants (79% African American, 9% Latino), 59% drank tap water, 80% bottled water. Only 17% drank tap water exclusively, 38% drank bottled water exclusively, 42% drank both. We found no significant differences in water preferences across age groups, from infancy to adulthood, or among ethnic groups. Ratings for taste, clarity, purity and safety were significantly higher for bottled water than tap water (P< 0.001). Only 24% were aware of fluoride in drinking water. We conclude bottled water was preferred over tap water in an urban minority pediatric population. Perceptions of the qualities of water seemed to drive drinking preferences. Public health strategies are needed to increase public awareness of the impact of bottled water consumption on oral health, household budgets and the environment.

No abstract