Extraction parameters and capillary electrophoresis analysis of limonin glucoside and phlorin in citrus byproducts

Edible plant by-products as source of polyphenols: prebiotic effect and analytical methods

Polyphenols with high chemical diversity are present in vegetables both in the edible parts and by-products. A large proportion of them remains unabsorbed along the gastrointestinal tract, being accumulated in the colon, where they are metabolized by the intestinal microbiota. These polyphenols have been found to have "prebiotic-like" effects. The edible plant industry generates tons of residues called by-products, which consist of unutilized plant tissues (peels, husks, calyxes and seeds). Their disposal requires special and costly treatments to avoid environmental complications. Reintroducing these by-products into the value chain using technological and biotechnological practices is highly appealing since many of them contain nutrients and bioactive compounds, such as polyphenols, with many health-promoting properties. Edible plant by-products as a source of polyphenols highlights the need for analytical methods. Analytical methods are becoming increasingly selective, sensitive and precise, but the great breakthrough lies in the pretreatment of the sample and in particular in the extraction methods. This review shows the importance of edible plant by-products as a source of polyphenols, due to their prebiotic effect, and to compile the most appropriate analytical methods for the determination of the total content of phenolic compounds as well as the detection and quantification of individual polyphenols.

Variation in limonin and nomilin content in citrus fruits of eight varieties determined by modified HPLC

The nomilin and limonin content in citrus fruits of different varieties was determined at fruit growth and maturation stages by HPLC. The results showed that the two limonoids can be separated, identified, and quantified in citrus fruits within 10 min by the developed method. The method exhibited good precision, repeatability, stability, and recovery rate. The content of limonin and nomilin in most citrus fruits presented an increasing trend initially, and then decreased during fruit growth and maturation; a peak was observed at the young fruit or fruit expansion stage. The dropped fruits also contained some amount of limonoids, suggesting their industrial application. The variation and cluster analyses results revealed that the orange varieties contained the highest amount of limonoids at the mature stage. The results of this study will enable better use of citrus limonoids.

Non-enzymatic browning in citrus juice: chemical markers, their detection and ways to improve product quality

Citrus juices are widely consumed due to their nutritional benefits and variety of pharmacological properties. Non-enzymatic browning (NEB) is one of the most important chemical reactions responsible for quality and color changes during the heating or prolonged storage of citrus products. The present review covers various aspects of NEB in citrus juice viz. chemistry of NEB, identifiable markers of NEB, analytical methods to identify NEB markers and ways to improve the quality of citrus juice. 2,5-Dimethyl-4-hydroxy-3(2H)-furanone (DMHF) is one of the promising marker formed during browning process with number of analytical methods reported for its analysis; therefore it can be used as an indicator for NEB process. Amongst analytical methods reported, RP-HPLC is more sensitive and accurate method, which can be used as analytical tool. NEB can be prevented by removal of amino acids/ proteins (via ion exchange treatment) or by targeting NEB reactions (e.g. blockage of furfural/ HMF by sulphiting agent).

Citrus limonoids: analysis, bioactivity, and biomedical prospects

Limonoids are a prominent group of secondary metabolites in citrus fruit. The bitter character of some compounds in this group has historically compromised the quality of citrus fruit and juice. Detecting bitter limonoids in citrus, understanding their origins, and developing methods for their removal from citrus juices have provided the basis for citrus limonoid research. Evaluation of the biological activity of citrus limonoids has indicated the potential of these compounds to improve human health as anticancer, cholesterol-lowering, and antiviral agents. This review chronicles the evolution of citrus limonoid research from defining their participation in citrus bitterness to their potential utilization as important contributors to improving human health and well-being.

Citrus juice modulates antioxidant enzymes and lipid profiles in orchidectomized rats

Oxidative stress and hypogonadism are two factors linked to the increased incidence of cardiovascular disease in males. Eating fruits and vegetables is known to reduce the incidences of oxidative stress. The objective of this research was to delineate whether drinking daily squeezed orange juice (OJ) or grapefruit juice (GJ) modulates oxidative stress and antioxidant enzymes while impacting cardiovascular risk factors in hypogonad male rats. In the present study, 36 1-year-old male rats were equally divided among the following four treatments: sham (control), orchidectomized (ORX), ORX + OJ, and ORX + GJ. After 60 days of drinking OJ or GJ, antioxidant capacity, cholesterol, and triglycerides in serum and superoxide dismutase (SOD), catalase (CAT), cholesterol, and triglycerides in liver were evaluated. Serum antioxidant capacity and SOD and CAT activities decreased (P < .05), while serum cholesterol and liver triglycerides increased (P < .05) in the ORX group compared with the sham group. In contrast to the ORX group, drinking OJ was ineffective while drinking GJ decreased (P < .05) cholesterol concentration in liver and in serum. Nevertheless, OJ and GJ decreased (P < .05) triglyceride concentration in liver and increased (P < .05) serum antioxidant capacity and SOD and CAT activities compared with the ORX group. In conclusion, drinking OJ or GJ prevented oxidative stress by enhancing total antioxidant capacity and elevating liver antioxidant enzymes while modulating cardiovascular risk factors.

Phenolics in cereals, fruits and vegetables: Occurrence, extraction and analysis

Consumption of plant foods, particularly fruits, vegetables and cereal grains is encouraged because they render beneficial health effects. Phenolics and polyphenolics are among the most desirable food bioactives because of their antioxidant activity, brought about by a number of pathways, or due to other mechanisms. The analysis of phenolics and polyphenolics requires their extraction possible purification and structure elucidation. This overview provides a cursory account of the source, extraction and analysis of phenolics in fruits, vegetables and cereals.

Analytical separation and detection methods for flavonoids

Flavonoids receive considerable attention in the literature, specifically because of their biological and physiological importance. This review focuses on separation and detection methods for flavonoids and their application to plants, food, drinks and biological fluids. The topics that will be discussed are sample treatment, column liquid chromatography (LC), but also methods such as gas chromatography (GC), capillary electrophoresis (CE) and thin-layer chromatography (TLC), various detection methods and structural characterization. Because of the increasing interest in structure elucidation of flavonoids, special attention will be devoted to the use of tandem-mass spectrometric (MS/MS) techniques for the characterization of several important sub-classes, and to the potential of combined diode-array UV (DAD UV), tandem-MS and nuclear magnetic resonance (NMR) detection for unambiguous identification. Emphasis will be on recent developments and trends.