Quality changes of pasteurised mango juice during storage. Part II: Kinetic modelling of the shelf-life markers

The present work shows the potential of the integrated fingerprinting-kinetics approach in evaluating shelf-life changes of pasteurised mango juice (cv. ‘Totapuri’). Seven mango juice formulations (i.e. control (mango puree and water), ascorbic acid-enriched (AA₂₅₀ and AA₅₀₀), citric acid-enriched (CA, CA + AA₂₅₀ and CA + AA₅₀₀) and sugar-enriched (S) samples) were pasteurised and stored at 42 °C for 8 weeks. In this part, the kinetics of the shelf-life markers selected from the multivariate fingerprinting approach was modelled. Changes in selected targeted parameters could be best described by a zero-order (colour values, °Brix, furfural, HMF), a first-order (ascorbic acid), a fractional conversion (fructose, glucose, oxygen) and a second-order model (sucrose). Differences in the rate constant were observed, with faster ascorbic acid degradation and furfural formation in AA-enriched samples and faster hydrolysis of sugars and HMF formation in CA-enriched samples compared to control samples. To describe changes in selected volatiles (terpenes, sulphur compounds, acids, ketones and esters), different kinetic models were selected. Two trends were observed: changes as affected by different mango juice formulations (e.g., faster reaction in CA-enriched samples or in a lower pH condition) and changes irrespective of the formulations. Referring to the literature, in general, acid-catalysed reactions, ascorbic acid degradation and oxidation reactions are the main reactions responsible for the observed quality changes in stored mango juice.     

Determination of 5-hydroxymethyl-2-furfural and 2-furfural in oils as indicators of heat pre-treatment

This study describes a method for the determination of 5-hydroxymethyl-2-furfural (HMF) and 2-furfural (F) in oils. The method entails liquid–liquid extraction and reversed-phase liquid chromatography. Spiked hazelnut oil was used to test the accuracy and reliability of the method. Furan compounds were extracted from oil using 70% methanol. Mean recoveries were 97 ± 2% and 99 ± 1% for HMF and F, respectively. To investigate the presence of HMF and F in oils, seven oily nuts and seeds were roasted at 180 °C for 30 min. Different oils were found to contain HMF and F ranging from 0.8 to 13.8 and 1.4 to 8.7 mg/kg, respectively. Increasing solvent polarity also increased the rate of HMF transferred to the oil. Spectral analyses of the 70% methanol extracts indicated that absorbance at 285 nm may be used to monitor the accumulation of furan compounds in oil phase during the roasting process of nuts.     

Evolution of potential and free furfural compounds in milk-based infant formula during storage

HPLC-DAD was used to monitor the evolution of potential and free furfural compounds (5-hydroxymethyl-2-furaldehyde, HMF; 2-furaldehyde, F; 2-furyl methyl ketone, FMC; and 5-methyl-2-furaldehyde, MF) over the shelf life of two types of infant powder formula: one supplemented with long-chain polyunsaturated fatty acids (LC-PUFA) in the form of microencapsulated fish oil (MFO), the other not supplemented with LC-PUFA. Following production, the formulae were stored at 25 and 37 °C. The initial furfural content in the supplemented formula was as follows: potential HMF (485.88 μg/100 g), potential F (167.13 μg/100 g), and free HMF (58.23 μg/100 g), while free F was not detected. In the unsupplemented formula, the following values were recorded: potential HMF (515.85 μg/100 g), potential F (170.29 μg/100 g), free HMF (84.92 μg/100 g), and free F (1.19 μg/100 g). In general, increased furfural content was observed during storage, an increase more pronounced in formula stored at 37 °C. Hardly any differences in furfural evolution during storage were observed between supplemented and unsupplemented infant formulae. The results suggest that the uses of MFO material for supplement formula not affected furfural formation. Neither FMC nor MF was formed in the formulae studied.     

Oxidative stability of virgin olive oil enriched with carnosic acid

The aim of this study was to evaluate the effect of the addition of carnosic acid on the oxidative stability of virgin olive oil. Two different amounts of carnosic acid (0.01 and 0.1 g/100 g oil) and two different temperatures (accelerated aging temperature, 60 °C; deep frying temperature, 180 °C) were considered. The influence of carnosic acid and heating time on the stability of the oils was studied by experimental design. The results obtained at 60 °C showed a dose dependent inhibition in the formation of primary and secondary oxidation products and a dose dependent enhancement of radical scavenging activity, which was only less significantly influenced by heating time. On the contrary, at 180 °C no protective effect against lipid oxidation was observed and the radical scavenging activity was practically zeroed by heating, probably as a consequence of a fast decomposition of carnosic acid.     

Assessment of Antioxidant Properties of Tamarind Fruit Pulp and its Effect on Storage Stability of African Bread Fruit Seed dhal and Flour

This study evaluated the antioxidant activities of tamarind fruit pulp in scavenging 1, 1-diphenyl-2-picryl hydroxyl radical (DPPH) and in suppressing thiobarbituric acid reactive substances (TBARS) formation, as a marker of lipid oxidation, in African breadfruit seed dhal and flour. Water and ethanol extracts of tamarind fruit pulp at different concentrations were used to scavenge DPPH radical. Parboiled (100°C; 15 min) breadfruit seeds were dehulled to seed dhal, oven-dried (50°C; 72 h), and half of the dhal milled into flour. Samples (100 g each) of the seed dhal and flour added and mixed together with aqueous suspensions (0, 1.0, 2.0, 3.0 or 5.0 g per 5 ml water) of tamarind fruit pulp were analysed for TBA values within 4 months of storage at 26 ± 2°C. The water and ethanol extracts scavenged DPPH in a dose-dependent manner. The ethanol extract had IC50 of 38.17 while the water extract had IC50 of 7.32, indicating much higher antioxidant activity of water extract. Tamarind fruit pulp inhibited lipid oxidation in breadfruit seed dhal and flour as evident from the mean thiobarbituric acid (TBA) value which decreased with increasing concentrations of the fruit pulp. Antioxidant activity of the fruit pulp was higher in the flour than in the dhal within 4 months of storage. Both seed dhal and flour treated with tamarind fruit pulp had lower mean TBA values ranging from 2.80 to 4.12 ppm Malonaldehyde as against 4.55 to 4.91 ppm for untreated samples. Tamarind fruit can thus be further studied for possible exploitation as a natural antioxidant for use in food, drug and cosmetic products.     

Phytochemical,antioxidant and pigment stability of açai (Euterpe oleracea Mart.) as affected by clarification,ascorbic acid fortification and storage

Açai juice at two clarity stages (semi-clarified and clarified) was compared to 100% açai pulp following ascorbic acid fortification to evaluate phytochemical and antioxidant changes during storage at 4 and 20 °C. Cyanidin-3-rutinoside (202 ± 5.8 mg/L) and cyanidin-3-glucoside (75 ± 4.8 mg/L) were the predominant anthocyanins in açai while 11 non-anthocyanin polyphenolics were detected in concentrations from 1.1 to 55 mg/L of açai pulp. Clarification of açai pulp resulted in a 27% loss in total polyphenolics (197 ± 6.9 mg gallic acid/100 mL) and in a 20% reduction in both total anthocyanins (729 ± 3.4 mg/L) and antioxidant capacity (54 ± 1.7 μmol Trolox equivalents/mL). Anthocyanin degradation followed first order kinetics, with half-lives ranging from 9.4 to 43 days for cyanidin-3-glucoside and from 18 to 82 days for cyanidin-3-rutinoside. Fortification with ascorbic acid accelerated anthocyanin degradation in clarified juice at both storage temperatures, likely due to the loss of polymeric anthocyanin forms (21%) during clarification. Although clarification enhanced the amount of monomeric anthocyanins present in açai juice which relates positively to the aesthetic quality, processing and handling regimes must be optimized to achieve maximum retention of their functional properties during storage.     

Effects of high hydrostatic pressure on the quality and shelf-life of jujube (Ziziphus jujuba Mill.) pulp

This study evaluated the effects of high hydrostatic pressure (HHP) on the microbial counts, physicochemical properties, bioactive compounds, and antioxidant capacity of jujube pulp. Additionally, this study compared the shelf life of jujube pulp following HHP (600 MPa/20 min) and thermal treatment (100 °C/10 min) during 40 days of storage at 4 °C and 15 °C. The microbial count of HHP-treated jujube pulp (≥ 400 MPa/20 min) was below the detection limit. Total soluble solids and total sugars were not significantly affected by HHP processing, and > 90% ascorbic acid was retained in HHP-treated samples. HHP slightly reduced pH and browning degree and increased total phenolic content, flavonoid content, and antioxidant capacity. HHP can be used as an alternative to thermal pasteurization of freshly squeezed jujube pulp.Industrial relevanceEffects of high hydrostatic pressure (HHP) processing and thermal treatment (TT) on microbiological quality, physicochemical properties, bioactive compounds and antioxidant activity in jujube pulp were investigated. Greater inhibition of microorganisms and better retention of ascorbic acid, total phenolics, flavonoid and antioxidant capacity were observed after HHP-treatment. The available data could be used to design the HHP parameters for high quality jujube juice. Further, this research would provide a useful method for preservation of jujube products and potential technical support for jujube commercial production.     

Acrylamide and 5-hydroxymethylfurfural formation during baking of biscuits: NaCl and temperature–time profile effects and kinetics

The present study aimed to investigate the effect of recipe and temperature–time on the formation of acrylamide and 5-hydroxymethylfurfural (HMF) during biscuit baking. Baking experiments were performed with biscuits of two different recipes, with and without NaCl, at 180 °C, 190 °C and 200 °C. Acrylamide and HMF reached highest concentrations at 200 °C for both recipes. The presence of NaCl in the biscuit formulation lowered acrylamide concentrations at 180 °C and 190 °C but not at 200 °C, and led to higher concentrations of HMF at all the tested temperatures. Sucrose hydrolysis was a key step in acrylamide and HMF formation during biscuit baking, even though a significant amount of acrylamide already had formed before the onset of sucrose hydrolysis. A lag phase was observed before sucrose hydrolysis occurred, which might depend on the melting of crystalline sucrose occurring at approximately 180 °C.A mathematical model based on the chemical reaction pathways was developed for the recipe with NaCl baked at 200 °C. The model described the chemical evolution during the last part of biscuit baking, and accurately predicted acrylamide and HMF content at the end of baking. The model showed the significant contribution of the reducing sugars to the formation of both acrylamide and HMF. The model could not be extended to the entire baking period because it was not possible to incorporate the lag phase observed before sucrose hydrolysis. The results reported in this study confirm that the kinetics of acrylamide and HMF formation in real food and dry systems may depend on the physical state of their precursors.     

Matrix dependent impact of sugar and ascorbic acid addition on color and anthocyanin stability of black carrot,elderberry and strawberry single strength and from concentrate juices upon thermal treatment

Heat stability of strawberry, elderberry and black carrot juices prepared from concentrate and fresh plant material was investigated at pH 3.5 by heating at 95 °C for 2 and 4 h, respectively. The impact of added saccharides (glucose, fructose, sucrose) and ascorbic acid on 5-hydroxymethylfurfural (HMF) formation, browning together with the stability of anthocyanins and their color properties were assessed using high performance liquid chromatography coupled to diode array detection (HPLC-DAD) and ultraviolet–visible (UV–Vis) spectrophotometry. Thermal degradation products of anthocyanins and saccharides were identified using liquid chromatography coupled to multistage mass spectrometry (LC–MSⁿ). Pigment stability and color changes depended on anthocyanin structure and juice matrix. Whereas a slight but insignificant stabilizing effect of added sugars and ascorbic acid was observed in juice prepared from black carrot concentrate, obvious color differences were detected in strawberry and elderberry juices when ascorbic acid was added. Manually squeezed juices from fresh plant material showed higher color stability compared to juices prepared from concentrate which might be due to the retention of polymeric matrix compounds in the former. The data presented may contribute to the development of advanced technological processes for the production of coloring foodstuff and food with improved color stability.     

Modelling of 5-hydroxymethylfurfural photo-degradation by UV irradiation. Influence of temperature and pH

The main aims of this study were (a) to prove that the UV irradiation of juices prevents the formation of 5-hydroxymethylfurfural (HMF), (b) to know the influence of temperature and pH on the UV photo-degradation of the HMF when it is unfortunately present in the juice (for example, after a previous thermal treatment or after a long storage period) and (c) to model this photo-degradation, proposing a reaction mechanism related to the power absorbed by the solution that depends on the HMF concentration.For these purposes a mid-pressure mercury lamp with emission wavelengths between 250 and 740 nm was used.Firstly, nectarine juice was irradiated to be sure that HMF was not synthesised. Then, aqueous solutions of 100 mg·L^− 1 HMF at pH 3, 4 and 5 were irradiated at 12, 25, 35 and 45 °C for 120 min. Aliquots were analysed to measure their HMF contents and absorption spectra.The photo-degradation data fitted well to both zero-order and pseudo-first-order kinetic models and the constant values were similar. The increases in both temperature and pH enhanced the photo-degradation, the optimal conditions inside the ranges studied being 45 °C and pH = 5, when a reduction of 60% of the initial content of HMF was reached.The spectral radiant power absorbed by the whole solution and the incident spectral radiant power reaching any depth of the reactor were evaluated taking into account the linear spherical emission model and using the Simpson integration method. Its dependence on the HMF concentration was also studied. A three stage degradation mechanism was proposed, matching both the zero-order and pseudo-first-order kinetic models previously obtained.     

Antioxidant activity in different fractions of tomatoes

The objective of this study was to determine the major antioxidants and antioxidant activity in different fractions (skin, seeds and pulp) of three tomato cultivars (Excell, Tradiro and Flavourine) grown under hydroponic conditions in a commercial greenhouse in New Zealand. It was found that the skin fraction of all cultivars had significantly (p < 0.05) higher levels of total phenolics, total flavonoids, lycopene, ascorbic acid and antioxidant activity (both in hydrophilic and lipophilic extracts as measured by the ABTS assay) compared to their pulp and seed fractions. The amount of antioxidants in each fraction was calculated on the basis of their actual fresh weights in whole tomato and it was found that the skin and seeds of the three cultivars on average contributed 53% to the total phenolics, 52% to the total flavonoids, 48% to the total lycopene, 43% to the total ascorbic acid and 52% to the total antioxidant activity present in tomatoes. These results show that removal of skin and seeds of tomato during home cooking and processing results in a significant loss of all the major antioxidants. Therefore, it is important to consume tomatoes along with their skin and seeds, in order to attain maximum health benefits.     

Role of Melissa officinalis in cholesterol oxidation: Antioxidant effect in model systems and application in beef patties

Cholesterol oxidation products (COPs) constitute a known health risk factor. The antioxidant effect of a lyophilized aqueous Melissa officinalis extract against cholesterol degradation and COPs formation during a heating treatment was evaluated in a model system (180 °C, 0–180 min) at a ratio of 2 mg extract/100 mg cholesterol. Furthermore, the plant extract was subsequently added to beef patties alone or incorporated within an oil-in-water olive oil emulsion to assess its effectiveness during cooking. Melisa extract protected cholesterol from thermal degradation in the model system, yielding higher remaining cholesterol and lower COPs values throughout the whole heating process. Maximum total COPs were achieved after 30 and 120 min of heating for control and melisa-containing samples, respectively. In cooked beef patties, even though the olive oil emulsion was used as flavor-masking approach, melisa extract off-flavor limited the maximum dose which could be added. At these doses (65 μg/g and 150 μg/g without and with the emulsion, respectively), no additional protective effect of melisa over the use of the emulsion was found. Addition of natural extracts into functional foods should definitively take into account sensory aspects.     

A novel approach to monitor the oxidation process of different types of heated oils by using chemometric tools

The oxidative stability of seven oils with different fatty acid profiles was assessed. Oxidation at 0, 2 and 4 h at 180 °C was monitored by measuring the absorbance of thiobarbituric acid reactive substances (TBARS) along the absorption spectrum (300–600 nm), the volatile aldehydes (HS-SPME–GC–MS) and the fatty acid profile (FID-GC).TBARS absorption spectrum behavior depended on the lipid composition of heated oils. Higher absorbance increments during heating were noticed at 390 nm compared to 532 nm (from 2 to 21 fold higher depending on the oil), pointing to its better sensitivity to detect oxidation. Furthermore, a close relationship between ABS₃₉₀, the loss of polyunsaturated fatty acids and their corresponding oxidation compounds (volatile aldehydes) was revealed by Principal Component Analysis.Multiparametric equations allowed predicting the formation of volatile aldehydes of heated oils by measuring only two parameters: TBARS₃₉₀ during their heating, and the lipid profile in unheated oils (MUFA, ω-3 and ω-6). Results pointed out the interest of choosing ABS₃₉₀ when the oxidative evolution of vegetable oils under heating is assessed by the TBARS test.     

Performance evaluation of a novel food packaging material based on clay/polyvinyl alcohol nanocomposite

The effectiveness of a novel, laminated clay/polyvinyl alcohol nanocomposite food-packaging film was examined by barrier analysis and food shelf-life monitoring. The effect of storage conditions on the film's oxygen permeability was studied and compared to commercial LLDPE/PET film as control. Additionally, pouches of 14 cm × 10.5 cm prepared from both films were filled with tomato paste as the food model, and stored at different temperatures (20–50 °C) and humidities (20–85% RH) for 10 days. Incorporating a coating layer containing 30 wt% (d.b.) of clay into polymer was found to improve its barrier properties, with drastic reduction of oxygen transmission rates (OTR) up to 99%, especially at 20% RH. While surrounding humidity affected the OTR of composite film significantly more than that of control film, the OTR of composite film was lower and less susceptible to temperature changes. The changes of food physical-chemical properties with time showed that the pouches of composite film significantly decreased ascorbic acid and lycopene oxidation of tomato paste by up to 88 and 37%, respectively. Furthermore, no discolouration occurred to the samples packaged by the nanocomposite film as compared to the control.Industrial relevanceA novel clay/polyvinyl alcohol nanocomposite film was developed with excellent barrier properties against oxygen. Evaluation of the performance of this food-packaging film indicated that incorporation of montmorillonite enhanced food preservation as suggested by decreased ascorbic acid and lycopene oxidation, and no discolouration of tomato paste. This new approach could be adopted by the food industry to assist commercial producers and retailers for preserving and extending the shelf-life of a variety of food products.     

Study of lipoxygenase and peroxidase as blanching indicator enzymes in peas: change of enzyme activity,ascorbic acid and chlorophylls during frozen storage

In this study, the effects of different blanching conditions on residual lipoxygenase (LOX) and peroxidase (POD) activities and quality changes in peas during frozen storage were studied. Peas were analysed for LOX and POD activities, ascorbic acid and chlorophylls a and b contents at 1, 2, 3, 6, 9 and 12 months of frozen storage. No regeneration of LOX and POD activities was determined in frozen-stored peas at −18 °C. The degradations of ascorbic acid and chlorophylls followed first-order kinetics. The half-lives of ascorbic acid, chlorophylls a and b derivatives in unblanched peas were found to be 3.30, 14.01 and 36.76 months during storage, respectively. Blanching at both 70 °C for 4.0 min and 80 °C for 2.0 min increased the half-life of ascorbic acid while it decreased those of chlorophylls a and b. Overall results suggested a blanching time of 2.0 min at 80 °C to inactivate 90% of initial POD activity, so, to retain quality parameters such as ascorbic acid and chlorophyll pigments in a storage period of 12 months at −18 °C.     

Polyphenols,carotenoids, and ascorbic acid in underutilized medicinal vegetables

The polyphenols, carotenoids, ascorbic acid, and protein were determined in 24 underutilized medicinal vegetables from Indonesia. Anacardium occidentale, Sauropus androgynus (L.) Merr., and Moringa pterygosperma Gaertn. leaves were rich sources of flavonoids, with 118–144 mg/100 g fresh weight. Quercetin, kaempferol, and chlorogenic acid were the predominant polyphenols among those measured in vegetables. Polyscias pinnata leaves and Solanum torvum Swartz fruits had the most phenolic acids, with 53 and 36 mg/100 g, respectively. Moringa pterygosperma had the most carotenoids among vegetables, with 14 mg β-carotene equivalents (βCE)/100 g. Ascorbic acid content of fresh vegetables was 12.03–494.43 mg/100 g. A. occidentale, S. androgynus, Ocimum americanum L., Cosmos caudatus H.B.K., and Carica papaya L. (papaya) leaves had more than 100 mg ascorbic acid/100 g. Thus, a number of underutilized vegetables from Indonesia may be rich sources of functional components including polyphenols and ascorbic acid.     

A kinetic study of oxidation development in sunflower oil under microwave heating: Effect of natural antioxidants

The antioxidative effects of carnosic acid and sesamol on sunflower oil under temperature-controlled microwave heating were investigated as a function of time and temperature. The concentration of conjugated diene hydroperoxide and p-anisidine value were determined spectrophotometrically, as measures of oxidation, during microwave heating of sunflower oil with or without added antioxidants at 40 °C, 60 °C and 80 °C. The kinetics of hydroperoxide formation was examined on the basis of previously proposed mechanisms and found to be of the half-order with respect to the concentration of conjugated diene hydroperoxide. The amounts of added antioxidants remaining in sunflower oil after different microwave heating periods at different temperatures were determined by HPLC-DAD. The results were interpreted in terms of antioxidative effects of carnosic acid and sesamol. Carnosic acid was found to be a more effective antioxidant than sesamol for sunflower oil.     

Reliable estimation of dietary exposure to furan from coffee: An automatic vending machine as a case study

Worldwide Food Safety Agencies have classified furan as carcinogenic and cytotoxic due to its effects in animal studies, and it has been associated with harmful effects to human health. It has been pointed out that coffee consumption is the major contributor to dietary furan exposure for adults. However, furan is highly volatile and its losses due to volatilization in the cup during the time expend to consume the coffee brew should be taken into account for a realistic estimation of the levels of furan exposure for humans. The aim of this study was to estimate the furan exposure to humans considering the time for consumption after preparation of the fresh beverage. Furan was determined in coffee brews acquired from automatic coffee vending machines placed in areas with high density of population. Furan levels in coffee beverages ranged from 11 to 262 ng/mL (mean = 171 ± 59.8). Furthermore, five different scenarios were settled immediately after the acquisition of coffee brews from the coffee vending machines in order to assess a realistic estimation of furan exposure. Furan content in coffee decreased from 170 up to 4 ng/mL after simulating the behavior of coffee consumption (~ 74% after standing at room temperature for 5 min, ~ 64% after stirring for 30 s and standing at room temperature up to 5 min, ~ 94% after stirring for 5 min, ~ 97% after 8 h in a sealed thermo and ~ 37% after being cooled one week at a fridge). These results suggest that it is mandatory to establish very precisely the furan levels in the final ready-to-drink beverage in order to obtain reliable estimations of the daily intake from coffee and to define potential strategies for mitigation. Furan intake from coffee ranged from 0.02 to 0.43 μg/kg b.w./day, resulting in a mean exposure of 0.31 μg/kg b.w./day.     

Mechanical and thermal characteristics of amaranth starch isolated by acid wet-milling procedure

Effects of soaking conditions during acid wet-milling of amaranth grain on mechanical and thermal properties of amaranth starch were investigated. A factorial design based on temperature (40–60 °C) and SO₂ concentration (0.1–1.0 g/L) was used. Dynamic oscillatory tests involved heating and cooling cycles (25–90 °C) with tempering at 90 °C followed by a frequency sweep (0.1–20 Hz) at constant temperature. Thermal properties of starch suspensions were based on DSC tests. Viscoelastic modulus and thermal properties were affected by both factors, being significant the interaction effect. Maximum values of viscoelastic modulus at the end of heating and cooling steps were determined for samples corresponding to soaking conditions of 50 °C and 1.0 g/L SO₂. Based on Ross-Murphy index from frequency sweep analysis it was found that paste behavior occurs at 60 °C and 0.1 g/L, while at 47.4 °C and 0.72 g/L starch suspension gave a strong gel. Onset (61.7 °C) and peak (66.2 °C) temperatures showed a minimum at 50 °C and 1.0 g/L. As SO₂ concentration decreased, the end of gelatinization took place at lower temperature. Maximum gelatinization enthalpy (12.7 J/g) was found at 40 °C and 0.1 g/L SO₂.     

Phenolic profiles and antioxidant activity of litchi pulp of different cultivars cultivated in Southern China

The phenolic profiles and antioxidant activity of litchi pulp of 13 varieties were investigated. The free, bound and total phenolic contents were 66.17–226.03, 11.18–40.54, and 101.51–259.18 mg of gallic acid equivalents/100 g, respectively. The free, bound and total flavonoid contents were 16.68–110.33, 10.48–22.75, and 39.43–129.86 mg of catechin equivalents/100 g, respectively. Free phenolics and flavonoids contributed averagely 80.1% and 75% to their total contents, respectively. Six individual phenolics (gallic acid, chlorogenic acid, (+)-catechin, caffeic acid, (?)-epicatechin, and rutin) were detected in litchi pulp by HPLC. The contents of each compound in free and bound fractions were determined. Significant varietal discrepancy in antioxidant activity was also found by FRAP and DPPH scavenging capacity methods. Antioxidant activity was significantly correlated with phenolic and flavonoid contents. Thus, phenolics and flavonoids exist mainly in the free form in litchi pulp. There were significant varietal differences in phytochemical contents and antioxidant activity of litchi pulp.