Ana Frígola

Analytical Methods for Determining Bioavailability and Bioaccessibility of Bioactive Compounds from Fruits and Vegetables: A Review

Determination of bioactive compounds content directly from foodstuff is not enough for the prediction of potential in vivo effects, as metabolites reaching the blood system may be different from the original compounds found in food, as a result of an intensive metabolism that takes place during absorption. Nutritional efficacy of food products may be ensured by the determination of bioaccessibility, which provides valuable information in order to select the appropriate dosage and source of food matrices. However, between all the methods available, there is a need to establish the best approach for the assessment of specific compounds. Comparison between in vivo and in vitro procedures used to determine bioaccessibility and bioavailability is carried out, taking into account the strengths and limitations of each experimental technique, along with an intensive description of actual approaches applied to assess bioaccessibility of bioactive compounds. Applications of these methods for specific bioactive compounds bioaccessibility or bioavailability are also discussed, considering studies regarding the bioavailability of carotenoids, polyphenolic compounds, glucosinolates, vitamin E, and phytosterols.

Ascorbic acid is the only bioactive that is better preserved by high hydrostatic pressure than by thermal treatment of a vegetable beverage.

Variations in levels of antioxidant compounds (ascorbic acid, total phenolics, and total carotenoids), total antioxidant capacity, and color changes in a vegetable (tomato, green pepper, green celery, onion, carrot, lemon, and olive oil) beverage treated by high hydrostatic pressure (HHP) were evaluated in this work. The effects of HHP treatment, four different pressures (100, 200, 300, and 400 MPa) and four treatment times for each pressure (from 120 to 540 s) were compared with those of thermal treatment (90-98 °C for 15 and 21 s). High pressure treatment retained significantly more ascorbic acid in the vegetable beverage than thermal treatment. However, no significant changes in total phenolics were observed between HHP treated and thermally processed vegetable beverage and unprocessed beverage. Color changes (a*, b*, L, chroma, h°, and ΔE) were less for pressurized beverage than thermally treated samples compared with unprocessed beverage.

A Comparative Study of the Analysis of Antioxidant Activities of Liquid Foods Employing Spectrophotometric, Fluorometric, and Chemiluminescent Methods

The antioxidant profile of liquid foods is complex and includes different lipid and water-soluble compounds. These should be considered when assessing total antioxidant capacity (TAC) of these beverages, since it may act synergistically rather than individually. This study describes and compares the use of spectrophotometric methods (Trolox equivalent antioxidant capacity, TEAC and 2,2-diphenyl-1-picrylhydrazyl, DPPH), fluorometric (oxygen radical antioxidant capacity, ORAC), and photochemiluminescence (PCL) for the measurement of the TAC of different liquid foods (fruit juice mixed with milk and vegetables beverage). An evaluation was also made for the influence of certain compounds (ascorbic acid, phenolic compounds, total carotenoids, and tocopherols) with antioxidant capacity that was present in the samples studied. The different methods studied allow the determination of the TAC of the analyzed foods in a precise and accurate way. The TAC values in the studied samples differ from the applied method. An overall antioxidant potency composite index was calculated by assigning each tests equal weight. When an index score was applied, ORAC method had the higher antioxidant capacity values in the analyzed liquid foods in comparison with the other methods. The correlations among the different methods used for the determination of the antioxidant capacity depend on food, that is, mainly due to compounds (lipid and water soluble) of the different food matrix. In addition, ascorbic acid was the main contributor to antioxidant capacity of fruit juice mixed with milk beverages measured with the different methods. However, in vegetables beverages, phenolic compounds were found to correlate more significantly with antioxidant capacity values.

Impact of high-pressure processing on vitamin E (α-, γ-, and δ-tocopherol), vitamin D (cholecalciferol and ergocalciferol), and fatty acid profiles in liquid foods.

In the present study, four high-pressure (HP) treatments (100, 200, 300, and 400 MPa) of 9 min duration were evaluated to assess their effect on the lipid fraction (fat-soluble vitamins and fatty acid profile) of an orange juice-milk and a vegetable beverage. After HP treatment, nonsignificant changes in vitamin D(2) and D(3) contents were observed for both beverages. An increase in vitamin E activity was observed in HP beverages when pressures >100 MPa were applied, mainly due to an increase in α-tocopherol content. Only a small reduction in fat content was found for the orange juice-milk beverage, but no changes were observed for the vegetable beverage. A significant decrease in SFA levels was observed in HP-treated (300-400 MPa) orange juice-milk. With regard to MUFA, a significant increase in oleic acid (C(18:1)) was found in both liquid foods. Nonsignificant differences in the PUFA profiles were observed after HP processing.

Effect of Stevia rebaudiana addition on bioaccessibility of bioactive compounds and antioxidant activity of beverages based on exotic fruits mixed with oat following simulated human digestion.

In order to determine the impact of Stevia rebaudiana (SR) addition on bioactive compounds bioaccessibility of a new developed functional beverage based on exotic fruits (mango juice, papaya juice and açaí) mixed with orange juice and oat, an in vitro gastrointestinal digestion was performed. Ascorbic acid, total carotenoids, total phenolics, total anthocyanins, total antioxidant capacity and steviol glycosides were evaluated before and after a simulated gastrointestinal digestion. Salivary and gastric digestion had no substantial effect on any of the major phenolic compounds, ascorbic acid, total antioxidant capacity and steviol glycosides, whereas carotenoids and anthocyanins diminished significantly during the gastric step. All analysed compounds were significantly altered during the pancreatic-bile digestion and this effect was more marked for carotenoids and total anthocyanins. However, phenolic compounds, anthocyanins, total antioxidant capacity and steviol glycosides bioaccessibility increased as did SR concentration. Ascorbic acid bioaccessibility was negatively affected by the SR addition.

Bioactive Components from Leaf Vegetable Products

Abstract Traditionally, plant-based products have been used for different purposes. From ancient times, people on all continents have long applied poultices and imbibed infusions of indigenous plants. Numerous reports regarding the use of leaf vegetable products for the treatment of many human diseases have been made. Proven medicinal properties include antioxidant, anti-inflammatory, antiallergic, antibacterial, and antiviral effects. Most of these properties can be attributed to its high content in bioactive compounds. Bioactive compounds are secondary metabolites of plants, which are extra nutritional constituents that typically occur in small quantities in foods. They are being intensively studied in order to evaluate their effects on health. These compounds may elicit a long range of different effects in man and animals eating the plants dependent on plant species and amount eaten. Plants with potent bioactive compounds are often characterized as both poisonous and medicinal, and their beneficial or adverse result may depend on the amount eaten and the context of intake. For typical food and feed plants with bioactive compounds with less pronounced effects, the intakes are usually regarded as beneficial. According to several studies, the great number of potentially beneficial compounds and their multifunctional properties makes plant products perfect candidates for the production of health-promoting food and food supplements. The aim of this chapter is to present a review in terms of leaf vegetable products as source of bioactive compounds, including its antioxidant and antimicrobial activities.

Quality parameters, bioactive compounds and their correlation with antioxidant capacity of commercial fruit-based baby foods

Comprehensive research is required to achieve the optimization of the antioxidant protection through baby foods, in particular, the commercially available fruit-based baby foods. This study investigated the physicochemical properties, ascorbic acid (AA), total carotenoids (TC), total phenolic content (TPC), trolox equivalent antioxidant capacity (TEAC) and oxygen radical absorbance capacity (ORAC) of 23 different commercially available fruit-based baby foods. The main contribution to the total antioxidant capacity (trolox equivalent antioxidant capacity and oxygen radical absorbance capacity) was provided by ascorbic acid, followed by phenolic compounds, in accordance with a mathematical equation obtained from the data: TEAC = 245.906 + 7.727 × (AA) + 1.988 × (TPC) − 0.008 × (TC) and ORAC = 318.662 + 2.775 × (AA) − 0.531 × (TPC) − 0.073 × (TC). Moreover, a positive correlation (r = 0.346, p < 0.05) was found for oxygen radical absorbance capacity and trolox equivalent antioxidant capacity methods. Baby foods with different kind of fruits used as ingredients showed higher antioxidant capacity. Among the commercial baby foods analysed in this work, that treated by gentle steam cooking process had high levels of bioactive compounds and antioxidant capacity.

Bioaccessibility of bioactive compounds after non-thermal processing of an exotic fruit juice blend sweetened with Stevia rebaudiana

A comparative study of the bioaccessibility of bioactive compounds and antioxidant capacity in a fruit juice-Stevia rebaudiana mixture processed by pulsed electric fields (PEF), high voltage electrical discharges (HVED) and ultrasound (USN) technology at two equivalent energy inputs (32-256kJ/kg) was made using an in vitro model. Ascorbic acid was not detected following intestinal digestion, while HVED, PEF and USN treatments increased total carotenoid bioaccessibility. HVED at an energy input of 32kJ/kg improved bioaccessibility of phenolic compounds (34.2%), anthocyanins (31.0%) and antioxidant capacity (35.8%, 29.1%, 31.9%, for TEAC, ORAC and DPPH assay, respectively) compared to untreated sample. This was also observed for PEF treated samples at an energy input of 256kJ/kg (37.0%, 15.6%, 29.4%, 26.5%, 23.5% for phenolics, anthocyanins, and antioxidant capacity using TEAC, ORAC and DPPH method, respectively). Consequently, pulsed electric technologies (HVED and PEF) show good prospects for enhanced bioaccessibility of compounds with putative health benefit.

IMPACT OF ELECTROTECHNOLOGIES AND ULTRASOUND TREATMENT IN THE FLAVONOIDS PROFILE OF A PAPAYA, MANGO AND STEVIA REBAUDIANA BEVERAGE

A high content of flavonoids in beverages is desirable not only due to their beneficial health effects, but also due to their ability to protect fruit juices from oxidation. However, food processing has a profound effect on these phytochemicals, with the further loss of most of their beneficial properties. For this reason, five flavonoids (catechin, rutin, hesperidin, quercetin and apigenin) were analyzed by HPLC in accordance to Kelebek et al. (2015) in a fruit juice-stevia beverage before and after pulsed electric fields (PEF), high voltage electical discharges (HVED) and ultrasounds (USN) treatments at two equivalent energy inputs. Catechin and hesperidin were the mayor phenolic compounds. For this two flavonoids, along with quercetin, PEF and USN treatments resulted in a significant increase compared to untreated beverage. By contrast, rutin decreased after PEF, HVED and USN treatment. The highest decrease was obtained when the beverage was treated by HVED at 256 kJ/kg. Apigenin content was far much lower in the USN treated beverage, as this compound may be severely affected by the cavitation phenomena. Results obtained highlight that individual flavonoids undergo different changes immediately after HVED, PEF and USN treatments, whereas others remain unchanged or are even enhanced.