Selection of extraction conditions of phenolic compounds from rambutan (Nephelium lappaceum L.) peel

Alginate beads loaded with rambutan extract: characterization and stability during in vitro gastrointestinal digestion

BACKGROUND

Fallen young rambutan fruit is an underrated agricultural waste which may contain several bioactive compounds. In this study, fallen young rambutan fruit was assessed regarding its phenolic contents and antioxidant activities. In order to expand its utilization, rambutan extract-loaded hydrogel beads were developed by a basic spherification technique using sodium alginate. The effect of ratios of polymer and extract and different calcium sources were evaluated. The recovery of bioactive compounds from the hydrogel beads was determined using in vitro gastrointestinal digestion models.

RESULTS

Use of 50% (v/v) ethanol yielded rambutan extract with good chemical properties. The production of hydrogel beads using a ratio of 1:3 with calcium lactate provided the highest production yield of 122.94%. The hydrogel beads developed using the ratio of 1:3 with a combination of calcium lactate and calcium chloride showed high recovery of phenolic compounds and antioxidant activity after simulated intestinal digestion, which were greater compared to unencapsulated extract.

CONCLUSION

The findings demonstrate that the ratio of wall material to rambutan extract and the calcium source influence the physical properties, chemical properties and in vitro gastrointestinal digestion stability of alginate beads. The obtained hydrogel beads may have potential for application in the food or pharmaceutical industries. © 2024 Society of Chemical Industry.

Developement of lactic acid fermentation of jackfruit (Artocarpus heterophyllus) seed drink and its physicochemical and sensory properties

The objective of this study was to create a plant-based drink from jackfruit seed. Firstly, jackfruit seed powder was hydrolyzed step by step with 0.2% α-amylase for 60 min and 0.3% glucoamylase for 90 min. The sample then was fermented with Lactiplantibacillus plantarum (L. plantarum) at 37 °C for 15 h. The findings indicated that hydrolysis and lactic acid fermentation enhanced the polyphenol, flavonoid, and antioxidant activity of jackfruit seed drink. Jackfruit seed drink was a favorable matrix for L. plantarum delivery. Moreover, the product underwent fermentation and reached the viability density of L. plantarum of 8.15 Log CFU/mL. The overall sensory liking score was rated between 5 and 5.5/7 points. Throughout the 35 days of storage period at 4-6 °C, the number of L. plantarum uncharged, whereas the bioactive compound and antioxidant activity of the product diminished by nearly 20-50% compared to the sample before storage. Overall, this research highlights the potential of the the fermented jackfruit seed drink as a probiotic plant-based drink with massive biological function and sensory appeal.

Preparation and Characterization of a Novel Longzhua mushroom Polysaccharide Hydrogel and Slow-Release Behavior of Encapsulated Rambutan Peel Polyphenols

Natural polyphenols have drawbacks such as instability and low bioavailability, which can be overcome by encapsulated slow-release systems. Natural polymer hydrogels are ideal materials for slow-release systems because of their high biocompatibility. In this study, Longzhua mushroom polysaccharide hydrogel (LMPH) was used to encapsulate rambutan peel polyphenols (RPP) and delay their release time to improve their stability and bioavailability. The mechanical properties, rheology, stability, swelling properties, water-holding capacity, RPP loading, and slow-release behavior of LMPH were investigated. The results showed that LMPH has adequate mechanical and rheological properties, high thermal stability, excellent swelling and water-holding capacity, and good self-healing behavior. Increasing the polysaccharide content not only improved the hardness (0.17-1.13 N) and water-holding capacity of LMPH (90.84-99.32%) but also enhanced the encapsulation efficiency of RPP (93.13-99.94%). The dense network structure slowed down the release of RPP. In particular, LMPH5 released only 61.58% at 48 h. Thus, a stable encapsulated slow-release system was fabricated using a simple method based on the properties of LMPH. The developed material has great potential for the sustained release and delivery of biologically active substances.

Nutritional quality of the traditionally cooked Zamnè, a wild legume and a delicacy in Burkina Faso: assessment of the process effectiveness and the properties of cooking alkalis

Zamnè is a wild legume and a famine food that attracts interest for its health benefits and has become a delicacy in Burkina Faso. This study aimed to determine the nutritional quality of the traditionally cooked Zamnè, appreciate the effectiveness of the traditional cooking process, and compare the properties of the traditionally used cooking alkalis (i.e., potash or plant ash leachate and sodium bicarbonate). Yet, as shown, the traditional cooking of Zamnè is a very aggressive process that results in high disintegration of cell walls and membranes and leaching of most water-soluble constituents and nutrients (i.e., free amino acids, soluble nitrogen, sugars, soluble dietary fibers, and soluble phenolics). In addition, the extensive boiling and the cooking alkalis induced the sequestration of calcium, iron, magnesium, and zinc, significantly impairing their bioaccessibility. Despite the difference in the modus operandi of the cooking alkalis, there was no significant difference in the cooking outcomes. The traditionally cooked Zamnè presented high dietary protein (4.8 g), lipid (3.3 g), fiber (6.7-7.7 g), and metabolizable energy (63-65 kcal) contents (per 100 g fresh weight). Most antinutritional factors (i.e., non-protein nitrogen, tannins, and trypsin inhibitors) were eliminated. The proteins were relatively well preserved despite the aggressive alkaline processing. They demonstrated an appreciable digestibility (75%) and predicted PER (1.5) and a fairly balanced essential amino acid composition - which should completely meet the requirements for adults. The lipid content and composition were also well preserved and contained predominantly linoleic (C18:2n-6), oleic (C18:1c9), stearic (C18:0), and palmitic (C16:0) acids (33, 34, 10, and 15% total fatty acids, respectively). Overall, though extensive alkaline cooking seems a straightforward option to overcome the hard-to-cook problem of Zamnè, processing alternatives might be useful to reduce nutrient losses, improve the digestibility of the final product, and capture its full nutritional value.

Purification of Coffee Polyphenols Extracted from Coffee Pulps (Coffee arabica L.) Using Aqueous Two-Phase System

Coffee pulp is an abundant residue from the coffee industry, but it still contains large amounts of valuable compounds such as polyphenols. The extraction of polyphenols from coffee pulp by the conventional method is accompanied by contaminated compounds. This study, therefore, applied an aqueous two-phase system consisting of different ratios of ethanol/ammonium sulfate to eliminate impurities from coffee-pulp crude extract. The purification efficiency was evaluated via total polyphenol content, antioxidant activity and two major polyphenols in coffee pulps including chlorogenic acid and caffeic acid. Results showed that phenolic compounds mostly predominated in the alcohol-rich phase in which the antioxidant activity was greatly increased after the purification process. Compared to un-purified crude-coffee extract, the antioxidant activity of the purified samples increased approximately 34%, which was assumed to occur due to the slight increase of chlorogenic acid and caffeic acid. Fourier-transform infrared spectroscopy supported the effectiveness of the purification process by eliminating some impurities.

Valorization of rambutan (Nephelium lappaceum L.) peel: Chemical composition, biological activity, and optimized recovery of anthocyanins

Chemical constituents and bioactive properties of rambutan (Nephelium lappaceum L.) peel were characterized and heat-/ultrasound-assisted extractions (HAE/UAE) of anthocyanins were optimized by response surface methodology. Five organic acids, the α-, γ-, and δ-tocopherol isoforms, and twenty-five fatty acids (36.8 % oleic acid) were identified, as well as a phenolic profile composed of ellagitannin derivatives, geraniin isomers, ellagic acid, and delphinidin-O derivatives. The extract showed antioxidant activity via lipid peroxidation (IC₅₀ = 2.79 ± 0.03 µg/mL) and oxidative hemolysis (IC₅₀ = 72 ± 2 µg/mL) inhibition, and displayed antibacterial and antifungal properties (MIC ≤ 1 mg/mL). On the other hand, no cytotoxicity was observed in tumor and non-tumor cell lines up to 400 µg/mL. The recovery of anthocyanins was more effective using HAE than UAE, allowing greater yields (16.2 mg/g extract) in just 3 min and using lower ethanol proportions. Overall, rambutan peel could be upcycled into bioactive ingredients and natural colorants for industrial applications.

Bioactive compounds, antioxidant capacity and anti-inflammatory activity of native fruits from Brazil

The purpose of this study was to extract, identify, and quantify the phenolic compounds in grumixama (Eugenia brasilienses Lam.) and guabiju (Myrcianthes pungens), native fruits from southern region of Brazil, and to explore their antioxidant and anti-inflammatory properties. The phenolic compounds were extracted with acidified water and acidified methanol and evaluated for their bioactive constituents, antioxidant capacity, and anti-inflammatory properties. Spectrophotometric quantification shows tannins to be the most prevalent at 2.3 to 5.8 g/100g fresh fruit with acidified methanol containing higher concentrations of different phenolics than acidified water. HPLC analysis indicates that gallic acid, catechin, vanillic acid, and ellagic acid are the most prevalent phenolics in the two fruits extracts. Scavenging of DPPH and NO radicals showed inhibition by as much as 95% and 80%, respectively, at 2.5 gallic acid equivalent (GAE)/mL of the extract. At 50 μg GAE/mL, the release of pro-inflammatory molecules NO and IL-6 was significantly reduced with acidified methanol extract having higher inhibitory activity. Our results revealed that these native fruits, grown in the south of Brazil, are rich sources of phenolic compounds and have great antioxidant and anti-inflammatory activity.

Simultaneous capture of hydrophilic and hydrophobic compounds from complex plants by biosurfactant-assisted mechanical amorphous dispersion extraction

A biosurfactant-assisted mechanical amorphous dispersion extraction (BA-MADE) procedure was established for the simultaneous capture of hydrophilic phenolic acids and hydrophobic tanshinones from Salvia miltiorrhiza. Single-factor experiments and the response surface methodology were used to optimize and analyze the crucial parameters for the method, such as the type and amount of amorphous-dispersion extractants, grinding time, extraction time and solid-to-liquid ratio. The optimized parameter values for the BA-MADE process were 407.02 mg of sodium chenodeoxycholate, a grinding time of 4.87 min, an extraction time of 4.92 min, and a solid-to-liquid ratio of 0.5:10 g/mL. The calibration curves of danshensu, rosmarinic acid, lithospermic acid, salvianolic acid B, salvianolic acid A, dihydrotanshinone I, cryptotanshinone, tanshinone I, and tanshinone II A exhibited good linearity in the range of 1-500 μg/mL (R² ≥ 0.9990). The limits of detection of nine analytes ranged from 5.46 to 130 ng/mL, the relative standard deviations (RSDs) of intraday and interday precision were less than 1.95 and 3.56%, respectively, and the recoveries of the real sample were in the range of 85-113%, with RSD% below 3.21%. The BA-MADE method was compared with previously reported methods, such as heating reflux extraction, ultrasonic extraction and microwave-assisted micellar extraction, and the results demonstrated that the developed method has significant advantages in the simultaneous extraction of hydrophilic and hydrophobic active components from Salvia miltiorrhiza.

Effects of dietary rambutan (Nephelium lappaceum L.) peel powder on growth performance, immune response and immune-related gene expressions of striped catfish (Pangasianodon hypophthalmus) raised in biofloc system

This study aimed to evaluate the effects of rambutan peel powder (RP) on growth, skin mucosal and serum immunities, and immune-related gene expression of striped catfish (Pangasianodon hypophthalmus) reared in a biofloc system. Three hundred fingerlings (17.14 ± 0.12 g fish^-1) were randomly selected and assigned to five treatments corresponding to five diets: 0 g kg^-1 (control - RP0); 10 g kg^-1 (RP10); 20 g kg^-1 (RP20); 40 g kg^-1 (RP40), and 80 g kg^-1 (RP80) for 8 weeks. At weeks 4 and 8 post-feeding, growth, skin mucus, and serum immunity parameters were determined, whereas immune-related gene expressions were performed at the end of the feeding trial. Based on the results, skin mucus lysozyme (SML) and skin mucus peroxidase (SMP) were significantly higher in fish fed the RP diets compared to the control diet (P < 0.05). The highest SML and SMP levels were observed in fish fed RP40 diet, followed by RP20, RP80, RP10, and RP0. Fish-fed RP diets had higher serum lysozyme and serum peroxidase activities, with the highest value found in the RP40 diet (P < 0.05), followed by RP20, RP80, and RP10. Similarly, immune-related gene expressions (IFN2a, IFN2b, and MHCII) in the liver were significantly up-regulated in fish fed RP40. Up-regulation (P < 0.05) of IL-1, IFN2a, IFN2b, and MHCII genes was also observed in fish intestines, with the highest values observed in fish fed RP40 diet, followed by RP10, RP20, RP80, and RP0. Fish-fed diet RP diets also showed enhanced growth and FCR compared to the control, with the highest values observed in fish fed diet RP40. However, no significant differences in survival rates were found among diets. In conclusion, dietary inclusion of RP at 40 g kg^-1 resulted in better growth performance, immune response, and immune related gene expressions of striped catfish (Pangasianodon hypophthalmus).

Storage Effect on Phenolic Compounds and Antioxidant Activity of Nephelium lappaceum L. Extract

Preparation of potential antioxidant extracts with less process for storing in a long period is preferable. N. lappaceum rind, well known as a promising source of phenolic antioxidants agricultural residue, was employed to prepare crude extracts by different solvents. The phenolic content, flavonoid content, antioxidant, and anti-tyrosinase activities of the extracts were evaluated. The stability of the potential extract was then assessed for phenolic content and antioxidant activity under various storage conditions. The extractive yields of crude phenolic extract ranged from 16.61 to 28.78%. The ethanolic extract of N. lappaceum rind exhibited potential antioxidant activities and contained a high amount of phenolics and flavonoid contents. The extract remained with a high amount of the phenolic content (up to 88.79%) and retained its antioxidant property under various temperatures (4, 25, and 45 °C) after the first week of the storage period. The results suggest that phenolic content and antioxidant activity of N. lappaceum rind extract, as a nutraceutical or anti-aging ingredients in cosmetics, could be stored at a temperature from 4 °C to 45 °C with or without oxygen exposure at least for 16 weeks.

Recovery of Bioactive Ellagitannins by Ultrasound/Microwave-Assisted Extraction from Mexican Rambutan Peel (Nephelium lappaceum L.)

Rambutan (Nephelium lappaceum L.) is a tropical fruit from Asia which has become the main target of many studies involving polyphenolic analysis. Mexico produces over 8 million tons per year of rambutan, generating a huge amount of agro-industrial waste since only the pulp is used and the peel, which comprises around 45% of the fruit’s weight, is left behind. This waste can later be used in the recovery of polyphenolic fractions. In this work, emerging technologies such as microwave, ultrasound, and the hybridization of both were tested in the extraction of phenolic compounds from Mexican rambutan peel. The results show that the hybrid technology extraction yielded the highest polyphenolic content (176.38 mg GAE/g of dry rambutan peel). The HPLC/MS/ESI analysis revealed three majoritarian compounds: geraniin, corilagin, and ellagic acid. These compounds explain the excellent results for the biological assays, namely antioxidant activity evaluated by the DPPH, ABTS, and LOI (Lipid oxidation inhibition) assays that exhibited great antioxidant capacity with IC₅₀ values of 0.098, 0.335, and 0.034 mg/mL respectively, as well as prebiotic activity demonstrated by a µMax (maximum growth) of 0.203 for Lactobacillus paracasei. Lastly, these compounds have shown no hemolytic activity, opening the door for the elaboration of different products in the food, cosmetic, and pharmaceutical industries.

Development of chitosan films incorporated with rambutan (Nephelium lappaceum L.) peel extract and their application in pork preservation

Chitosan (CS) films containing 0, 1, 3 and 5% (w/w) of polyphenol-rich rambutan peel extract (RPE) were developed. The micro-structural characterization and physical and functional properties of the films were determined. Results showed RPE formed strong interactions with CS, making film inner micro-structure become uniform and film crystallinity decline. Amongst different films, CS film containing 5% of RPE showed the lowest light transmission, moisture content (28.35%), water solubility (46.07%), water vapor permeability (8.41 × 10^-10 g m^-1 s^-1 Pa^-1) and oxygen permeability (0.28 cm³ mm m^-2 day^-1 atm^-1). Meanwhile, CS film containing 5% of RPE exhibited the highest tensile strength (38.87 MPa) and elongation at break (51.73%) and the strongest antioxidant and antimicrobial activities. Finally, pork was wrapped with the films and stored at 4 °C for 8 days. Results showed pork wrapped with CS film containing 5% of RPE presented the lowest total volatile basic nitrogen level (9.17 mg/100 g), thiobarbituric acid reactive substance value (0.51 mg malondialdehyde/kg) and total viable count (4.53 log colony forming unit/g) and the best sensory attributes on the eighth day. Our results suggested the potential of CS film containing 5% of RPE as an active packaging material in pork preservation.

Validated Stability-Indicating GC-MS Method for Characterization of Forced Degradation Products of Trans-Caffeic Acid and Trans-Ferulic Acid

When dealing with simple phenols such as caffeic acid (CA) and ferulic acid (FA), found in a variety of plants, it is very important to have control over the most important factors that accelerate their degradation reactions. This is the first report in which the stabilities of these two compounds have been systematically tested by exposure to various different factors. Forced degradation studies were performed on pure standards (trans-CA and trans-FA), dissolved in different solvents and exposed to different oxidative, photolytic and thermal stress conditions. Additionally, a rapid, sensitive, and selective stability-indicating gas chromatographic-mass spectrometric method was developed and validated for determination of trans-CA and trans-FA in the presence of their degradation products. Cis-CA and cis-FA were confirmed as the only degradation products in all the experiments performed. All the compounds were perfectly separated by gas chromatography (GC) and identified using mass spectrometry (MS), a method that additionally elucidated their structures. In general, more protic solvents, higher temperatures, UV radiation and longer storage times led to more significant degradation (isomerization) of both trans-isomers. The most progressive isomerization of both compounds (up to 43%) was observed when the polar solutions were exposed to daylight at room temperature for 1 month. The method was validated for linearity, precision as repeatability, limit of detection (LOD) and limit of quantitation (LOQ). The method was confirmed as linear over tested concentration ranges from 1−100 mg L⁻¹ (r²s were above 0.999). The LOD and LOQ for trans-FA were 0.15 mg L⁻¹ and 0.50 mg L⁻¹, respectively. The LOD and LOQ for trans-CA were 0.23 mg L⁻¹ and 0.77 mg L⁻¹, respectively.