Effect of heat treatment on the content of some bioactive compounds and free radical-scavenging activity in pungent and non-pungent peppers

Raw and heat-treated (boiled and grilled) pungent and non-pungent peppers (poblano, bell, chilaca, caribe, jalapeño, serrano, habanero and manzano) were evaluated for their content of some bioactive compounds and free radical-scavenging activity. Boiling and grilling were performed under household conditions. Ascorbic acid content in raw peppers varied from 306 to 3438 μg/g. This content was reduced 15–87% by heat treatments. Total carotenoids content in raw peppers ranged between 1 and 156 μg/g. β-Carotene represented 3–78% of total carotenoids in raw peppers. β-Carotene content was reduced (1–45%) by heat treatments. Free radical-scavenging activity varied widely (7–101 μmol TE/g) in raw peppers. Boiling and grilling reduced (6–93%) sequentially the antiradical activity of pungent peppers. In contrast, gradual increases of antiradical activity in non-pungent peppers were induced by boiling and grilling. Household heat treatment altered highly the content of bioactive/antioxidant compounds in tested peppers.     

Fast determination of capsaicinoids from peppers by high-performance liquid chromatography using a reversed phase monolithic column

This article reports the development of a rapid and reproducible method of HPLC with fluorescence detection for the determination and quantification of the main capsaicinoids (nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin and homodihydro-capsaicin) present in hot peppers by employing a monolithic column. The type of column employed is a RP-18e (100 mm × 4.6 mm) monolithic column. A gradient method was utilised for the chromatographic separation: solvent A: water (0.1% acetic acid) and solvent B: methanol (0.1% acetic acid). A study was also made of the robustness of the method in respect of the conditions of temperature in the separation column (15–40 °C), the solvent flowrate (4–7 mL min⁻¹), the injection volume (10–50 μL), and the percentage of methanol in the sample (25–100%). The repeatability and reproducibility of the method showed relative standard deviations of less than 2%. The robustness of the method was determined by utilising different injection volumes and different percentages of methanol in the extracts. The method developed has then been utilised for the quantification of the major capsaicinoids present in different varieties of hot peppers grown in Spain. The capsaicinoids have been separated in a time of less than 8 min.     

Capsaicinoid Contents in Peppers and Pepper-Related Spicy Foods

The quantification of the major capsaicinoids, namely nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin, and homodihydrocapsaicin, present in spicy foods made from peppers has been performed. The capsaicin content is directly related to the pungency properties of foods that contain hot peppers. The samples studied included 10 different dried hot peppers, 19 hot sauces, 4 kinds of paprika, and 4 different ketchups. The range of concentrations of capsaicinoids found were as follows: dried hot peppers (554.1–1705.9 mol kg^?1), paprikas (582.0–665.0 mol kg^?1), spicy ketchups (4.0–12.4 mol kg^?1), and hot sauces (4.6–843.8 mol kg^?1). Variability in the capsaicinoid content was found, with capsaicin and dihydrocapsaicin present at the highest levels. The capsaicin content was generally higher than the dihydrocapsaicin content.     

Effect of cooking on the antioxidant properties of coloured peppers

Pepper (Capsicum annum L.) has long been recognized as an excellent source of antioxidants, being rich in ascorbic acid and other phytochemicals. This study was conducted to investigate the effect of different cooking methods on the antioxidant properties of coloured peppers. Six varieties of peppers were subjected to different cooking methods, such as microwave heating, stir-frying and boiling in water, for 5 min individually. The cooked and raw peppers were analyzed for radical-scavenging activity (RSA) and total polyphenol content (TP) using 1,1-diphenyl-2-picrylhydrazyl–high-pressure liquid chromatography (DPPH)–HPLC and Folin-Ciocalteu methods, respectively. The samples were also evaluated for ascorbic acid content (AsA) by HPLC. Total carotenoid content was determined spectrophotometrically. Results suggest that there is no significant (P > 0.05) difference in RSA, TP, AsA and total carotenoid contents between the cooked and raw peppers when processed for 5 min. However, the cooked peppers show marked differences (P < 0.05) in the RSA, TP and AsA when cooked for 5 min in boiling water with further reduction observed after boiling for 30 min. This may be due to the leaching of antioxidant compounds from the pepper into the cooking water during the prolonged exposure to water and heat. Therefore, it is vital to use less water and cooking time and also to consume the water used for boiling so as to obtain the optimum benefits of bioactive compounds present in peppers. It is concluded that microwave heating and stir-frying without using water are more suitable cooking methods for pepper, to ensure the maximum retention of antioxidant molecules.     

Applications of argentation solid phase extraction to the capsaicinoids: Purification of commercial standards and isolation of homodihydrocapsaicin (8-methyl) from ‘Bhut Jolokia’

Argentation solid phase extraction was employed to purify commercial standards of capsaicin (6-ene-8-methyl) and dihydrocapsaicin (8-methyl). The purity was improved from 96.7% to 99.6% and from 89% to 96%, respectively, with 75% and 60% yield, respectively. Reversed phase solid phase extraction, argentation solid phase extraction, and preparative liquid chromatography with a C30 phase were used to isolate capsaicinoids from the fruits of ‘Bhut Jolokia’ peppers. The compounds capsaicin (6-ene-8-methyl) and dihydrocapsaicin (8-methyl) comprised 74% and 21% of the total mass of capsaicinoids, respectively. The remaining 5% of the capsaicinoids mass included the compounds: nordihydrocapsaicin (7-methyl), N-vanillylnonanamide, two homocapsaicin isomers, N-vanillyldecanamide, and two homodihydrocapsaicin isomers. All but one of these compounds were identified by comparison to known standards. The presence of homodihydrocapsaicin (8-methyl) was confirmed by its absorbance at 280 nm, electrospray ions at m/z 322 and m/z 137, elution just prior to homodihydrocapsaicin (9-methyl), and a carbon-13 NMR spectrum that matched predicted chemical shifts.     

The influence of fruit ripening on the phytochemical content and biological activity of Capsicum chinense Jacq. cv Habanero

During the past decade, it has been reported that the consumption of certain foods and spices such as pepper may have a positive effect on health. The present study evaluates the influence of fruit ripening on total phenols, flavonoids, carotenoids and capsaicinoids content and antioxidant, hypoglycaemic and anticholinesterase activities of Capsicum chinense Jacq. cv Habanero. The chemical investigation showed a different composition between the two stages of ripening (immature and mature). Generally, the concentration of carotenoids and capsaicinoids increased as the peppers reached maturity, whereas the concentration of phenols declined. The immature fruits showed the highest radical scavenging activity (IC₅₀ of 97.14 μg/ml). On the contrary, the antioxidant activity evaluated by the β-carotene bleaching test showed a significant activity for mature peppers (IC₅₀ value of 4.57 μg/ml after 30 min of incubation). Mature peppers inhibited α-amylase with an IC₅₀ of 130.67 μg/ml. The lipophilic fractions of both mature and immature peppers exhibited an interesting and selective inhibitory activity against α-amylase with IC₅₀ values of 29.58 and 9.88 μg/ml, respectively. Both total extracts of mature and immature peppers inhibited butyrylcholinesterase selectively. The obtained results underline the potential health benefits as a result of consuming C. chinense Habanero and suggest that it could be used as new valuable flavour with functional properties for food or nutriceutical products on the basis of the high content of phytochemicals and found biological properties.     

Analysis of glycative products in sauces and sauce-treated foods

Content of Maillard reaction products (MRPs) such as pentosidine, carboxymethyllysine and furosine in soybean sauce, sour-sweet sauce, tomato sauce, barbecue sauce, and sauce-treated chicken, pork, beef, salmon and cod was analysed. In test sauces, MRP content was in the range of 10–692 μg/100 mL sample. MRP content in raw, boiled, fried and baked foods was in the range of 10–76 μg/100 g sample. Boiling, frying and baking caused significantly higher MRP levels in test foods (P < 0.05). MRP levels in soybean sauce, sour-sweet sauce and barbecue sauce-treated foods were in the range of 1094–2424, 1494–3146 and 1400–2926 μg/100 g sample. The interactions of sauce, heating and frying oil markedly enhanced the formation of MRPs in sauce-treated foods. Because MRPs are glycative products; thus, patients with glycation associated diseases may consider limiting the dietary use of these sauces.     

Determination of capsaicin and dihydrocapsaicin in Capsicum anuum and related products by capillary electrophoresis with a mixed surfactant system

An easy, rapid, sensitive, and cheap capillary electrophoresis (CE) method based a mixed surfactant system formed by sodium dodecyl sulphate (SDS) and polyoxyethylene sorbitan monolaurate (Tween 20) as modifier in the buffer was reported. Quantitative analysis of capsaicin and dihydrocapsaicin in Capsicum anuum, pepper sauce and porous capsicum plaster was demonstrated. After conducting a series of optimisations, baseline separation was obtained for the analytes within 5 min under the optimum conditions (15 mM sodium tetraborate–0.05% (v/v) Tween 20–2.2 mM SDS buffer (pH 10.1), 20 kV voltage, 214 nm UV detection). The method resulted in excellent linearity, with r² of regression equation of 0.9994 and 0.9996 for capsaicin and dihydrocapsaicin, respectively. Recoveries were in the range 90–107% and 92–109% for capsaicin and dihydrocapsaicin, respectively.     

Relationship between the solubility,dosage and antioxidant capacity of carnosic acid in raw and cooked ground buffalo meat patties and chicken patties

Antioxidant capacity of oil soluble and water dispersible carnosic acid (CA) extracted from dried rosemary leaves using HPLC was evaluated at two different dosages (22.5 ppm vs 130 ppm) in raw and cooked ground buffalo meat patties and chicken patties. Irrespective of total phenolic content, CA extracts reduced (p < 0.05) the thiobarbituric acid reactive substances (TBARS) by 39%–47% and 37%–40% in cooked buffalo meat and chicken patties at lower dosage (22.5 ppm) relative to control samples. However, at higher dosage (130 ppm) the TBARS values were reduced (p < 0.05) by 86%–96% and 78%–87% in cooked buffalo meat and chicken patties compared to controls. The CA extracts were also effective in inhibiting (p < 0.05) peroxide value and free fatty acids in cooked buffalo meat and chicken patties. The CA extracts when used at higher dosage, were also effective in stabilizing raw buffalo meat color.     

反相高效液相色谱法测定辣椒中4种辣椒碱类成分的含量

目的：建立同时测定辣椒中辣椒素、二氢辣椒素、降二氢辣椒素和高辣椒素 4 种辣椒碱类成分的反相高效液相色谱方法,并对30个辣椒品种中辣椒碱含量进行比较。方法：采用Nucleosil C18色谱柱(4.6mm×250mm,5μm);流动相乙腈-水,梯度洗脱;柱温45℃;流速1.0mL/min;检测波长280nm。结果：辣椒素、二氢辣椒素、降二氢辣椒素和高辣椒素的线性关系良好,范围均为1.0～160.0μg/mL,相关系数在0.9965～0.9993之间,精密度、稳定性实验的相对标准偏差均低于2.7%,加标回收率介于97%～99%。辣椒碱在不同辣椒品种中含量差异显著。结论：对30个样品测定结果稳定,重现性好。当辣椒素和二氢辣椒素含量大于0.1%时,辣椒有明显的辣感。     

Stability and bioaccessibility of different forms of carotenoids and vitamin A during in vitro digestion

Vitamin A deficiency is a public health issue in developing countries and promoting dietary carotenoids as precursors is a promising strategy. However, carotenoids present in numerous fruits and vegetables are unstable and poorly bioaccessible. This study evaluated these two parameters during in vitro digestion of carotenoids and retinoids from carrot juice, raw and cooked spinach, micronutrient-fortified flour and standards without food matrix. Standards were unstable whereas vitamin A from fortified flour and native food carotenoids were generally better protected by the food matrix (30–100% remaining versus 7–30% for standards). Hydrothermal cooking did not influence spinach carotenoid digestive stability but decreased their contents, phenomenon compensated by a significantly better micellarisation from 15-fold for β-carotene to 72-fold for lutein. Finally, carrot juice provided the greatest amount of bioaccessible provitamin A with 1850 μg/100 g dry matter (DM) versus 790 and 80 μg/100 g DM in cooked and raw spinach, respectively.     

Influence of different drying methods on carotenoids and capsaicinoids of paprika (Cv., Jalapeno)

Influence of Refractance Window™ Drying (RWD), a novel contact drying method, on carotenoids, capsaicinoids, Retinol Activity Equivalent (RAE) and Scoville Heat Unit (SHU) of paprika (Cv., Jalapeno) was investigated in comparison with freeze drying (FD), oven drying (OD), and natural convective drying (NCD) methods. Eight carotenoids (capsanthin, capsorubin, capsolutein, β-carotene, β-cryptoxanthin, mutatoxanthin, violaxanthin and zeaxanthin) and five capsaicinoid analogues (capsaicin, dihydrocapsaicin, homodihydrocapsaicin, isodihydrocapsaicin, nordihydrocapsaicin) were identified in paprika. All these components were significantly (P < 0.05) decreased by the RWD, FD and OD methods. However, due to ongoing synthesis, the NCD method resulted in higher carotenoids, except violaxanthin and mutatoxanthin, and capsaicinoids content than those of the others, even puree. Mutatoxanthin, naturally occurring pigment in red pepper, could only be detected in FD paprika. The highest RAE and SHU values, which were derived from the data of carotenoids and capsaicinoids, respectively, were also determined in NCD paprika.     

Mapping the Pungency of Green Pepper Using Hyperspectral Imaging

The pungency level of green peppers is dependent on the amounts of capsaicin and dihydrocapsaicin they contain. This study was conducted to develop a non-destructive method for the prediction and mapping of the capsaicin and dihydrocapsaicin contents in green pepper. Hyperspectral images of 200 total green peppers of three varieties were acquired in the wavelength range of 1000–1600 nm, from which the mean spectra of each pepper variety were extracted. The reference capsaicin and dihydrocapsaicin contents of the samples were measured by high-performance liquid chromatography. Quantitative calibration models were built using partial least squares (PLS) regression with different spectral preprocessing techniques; the best performance was found by normalizing the preprocessed spectra with correlation coefficients (r_pred) of 0.86 and 0.59, which showed the standard errors of prediction (SEPs) of 0.09 and 0.03 mg/g for capsaicin and dihydrocapsaicin, respectively. Seventeen and 16 optimal wavebands were selected using the successive projections algorithm; r_pred of 0.88 and 0.68 and SEPs of 0.084 and 0.027 mg/g were obtained for capsaicin and dihydrocapsaicin, respectively, from the newly developed PLS calibration models using these optimal wavebands. The successive projections algorithm (SPA)-PLS model was used to map the capsaicin and dihydrocapsaicin contents of the green peppers. These maps provided detailed information on the pungency levels of the tested green peppers. The results of this study indicated that hyperspectral imaging is useful for the rapid and non-destructive evaluation of the pungency of green peppers.     

Evaluation of the effects of selected plant-derived nutraceuticals on the quality and shelf-life stability of raw and cooked pork sausages

The effect of lutein (200 μg/g meat), sesamol (250 μg/g meat), ellagic acid (300 μg/g meat) and olive leaf extract (200 μg/g meat) on total viable counts (TVC), pH, water holding capacity (WHC), cooking loss, lipid oxidation (thiobarbituric acid-reactive substances, TBARs), colour stability, texture and sensory evaluation of fresh and cooked pork sausages stored in aerobic or modified atmosphere packs (MAP) was investigated. Addition of sesamol, ellagic acid and olive leaf extract reduced (P < 0.001) lipid oxidation in all packaged raw and cooked pork sausages. Antioxidant potency followed the order: sesamol 250 > ellagic acid 300 > olive leaf extract 200 > lutein 200 for both raw and cooked pork sausages. Addition of sesamol increased (P < 0.001) WHC on days 2 and 12 of MAP storage. Meat addition of lutein, sesamol, ellagic acid and olive leaf extract had no detrimental effect on pH, cooking losses, TVCs, tenderness, juiciness, texture or product flavour. Lutein, sesamol, ellagic acid and olive leaf extract were effective as natural functional ingredients in suppressing lipid oxidation and have the potential to be incorporated into functional raw and cooked pork sausages.     

Antioxidant activity and phenolic content of 16 raisin grape (Vitis vinifera L.) cultivars and selections

Six raisin grape cultivars and 10 new raisin grape selections were analyzed for antioxidant activity (ABTS assay) and for total and individual phenolic compounds. Samples were freeze–dried and values are reported on a dry weight basis. Antioxidant activity across the 16 samples ranged from 7.7 to 60.9 μmol Trolox/g DW, with A95-27 exhibiting the greatest activity. Total phenolic content, determined in gallic acid equivalents using the Folin–Ciocalteau assay, ranged from 316.3 to 1141.3 mg gallic acid/100 g DW and was strongly correlated (r = 0.990) with antioxidant results. Concentrations of individual phenolics were determined by HPLC. trans-Caftaric acid was the predominant compound in all samples. A95-15 contained the lowest concentration (153.5 μg/g DW) of caftaric acid, while Fiesta contained the highest concentration (598.7 μg/g DW). Selections A56-66, A95-15, and A95-27 had much higher levels of catechin (86.5–209.1 μg/g DW) and epicatechin (126.5–365.7 μg/g DW) than the other samples.     

Comparative Study of Capsaicinoid Composition in Capsicum Peppers Grown in Brazil

Twenty different varieties of Capsicum pepper cultivars belonging to four species (Capsicum chinense, Capsicum annuum, Capsicum frutescens, and Capsicum baccatum) were characterized in terms of their capsaicinoid and total phenolic content. The peppers were sown in a farm in the southeastern region of São Paulo State. The determination of capsaicinoids was performed by ultra-performance liquid chromatography. The total phenolic content was determined spectrophotometrically with the Folin-Ciocalteu reagent. Results were expressed as µg capsaicinoid/g fresh pepper and as Scoville heat unit. A wide variation was observed among the compositions of capsaicinoids. Capsaicin and dihydrocapsaicin were the most abundant peaks. Capsaicinoids were not identified in the pepper varieties Cheiro Verde, Cambuci Verde, Cambuci Vermelha, and Biquinho. The spiciest pepper was Naga Jolokia (119,016 Scoville heat unit). Regarding the phenolic contents, a large variability was observed. Total phenolic content ranged from 0.35 mg gallic acid equivalent/g in Cambuci Verde to 3.06 mg gallic acid equivalent/g in Naga Jolokia. The current study may benefit consumers, the food, and pharmaceutical industries due to the increasing interest in pharmacological compounds present in hot and sweet Capsicum peppers.     

Effect of cooking methods on fatty acids,conjugated isomers of linoleic acid and nutritional quality of beef intramuscular fat

The effect of boiling, microwaving and grilling on the composition and nutritional quality of beef intramuscular fat from cattle fed with two diets was investigated. Longissimus lumborum muscle from 15 Alentejano young bulls fed on concentrate or pasture was analyzed. Cooking losses and, consequently, total lipids, increased directly with the cooking time and internal temperature reached by meat (microwaving > boiling > grilling). The major changes in fatty acid composition, which implicated 16 out of 34 fatty acids, resulted in higher percentages in cooked beef of SFA and MUFA and lower proportions of PUFA, relative to raw meat, while conjugated linoleic acid (CLA) isomers revealed a great stability to thermal processes. Heating decreased the PUFA/SFA ratio of meat but did not change its n−6/n−3 index. Thermal procedures induced only slight oxidative changes in meat immediately after treatment but hardly affected the true retention values of its individual fatty acids (72–168%), including CLA isomers (81–128%).     

Evaluation of the effects of selected phytochemicals on quality indices and sensorial properties of raw and cooked pork stored in different packaging systems

The effects of lutein (100, 200 μg/g muscle), sesamol (250, 500 μg/g muscle), ellagic acid (300, 600 μg/g muscle) and olive leaf extract (100, 200 μg/g muscle) on lipid oxidation (thiobarbituric acid-reactive substances TBARs), colour (CIE L∗, a∗, b∗), pH, texture profile analysis (TPA), water holding capacity (WHC), cooking losses and sensorial properties of fresh and cooked pork patties were investigated. Raw and cooked minced pork (M. longissimus thoracis et lumborum) containing added lutein, sesamol, ellagic acid or olive leaf extract were stored aerobically or in modified atmosphere packs (MAP) for up to 8 and 12 days, respectively. Lutein, sesamol, ellagic acid and olive leaf extract had no significant effect on microbial status, cook loss, pH or WHC. Lipid oxidation was reduced (P < 0.001) in raw and cooked pork patties stored in aerobic packs and in MAP following addition of sesamol, ellagic acid and olive leaf extract. Antioxidant effectiveness in raw and cooked patties was in the order: sesamol = ellagic acid > olive leaf extract > lutein. Lutein increased (P < 0.001) b∗ yellowness values in raw pork patties. Addition of lutein, sesamol, ellagic acid and olive leaf extract to pork had no detrimental effects on the organoleptic properties of cooked patties but altered (P < 0.05) instrumental textural attributes. Results highlight the potential of using natural functional ingredients in the development of functional pork products with enhanced quality and shelf-life.     

Effects of binary solvent extraction system,extraction time and extraction temperature on phenolic antioxidants and antioxidant capacity from mengkudu (Morinda citrifolia)

An investigation into the effects of ethanol concentration (0–100%, v/v), extraction time (20–120 min) and extraction temperature (25–65 °C) on the extraction of phenolic antioxidants from mengkudu (Morinda citrifolia) was performed using a single-factor experiment. Total phenolic content (TPC) and total flavonoid content (TFC) assays were used for determination of phenolic compounds. Antioxidant capacity was evaluated by measuring the scavenging effect on 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radicals. Experimental results showed that extraction conditions had significant effect on extraction of phenolic compounds and antioxidant capacities. The optimised conditions were 40% ethanol for 80 min at 65 °C, with values of 919.95 mg GAE/100 g DW for TPC, 472.73 mg CE/100 g DW for TFC, 791.71 μmol TEAC/100 g DW for ABTS and 1928.5 μmol TEAC/100 g DW for DPPH. TPC was significantly correlated with DPPH under the effects of ethanol concentration (r = 0.932) and extraction time (r = −0.938).     

Effect of refining processes on antioxidant capacity,total contents of phenolics and carotenoids in palm oils

Antioxidant capacity (AC), total phenolic content (TPC) and total carotenoid content (TCC) in palm oils at various stages of the refining process from two technological modes were determined. The obtained mean FRAP and DPPH values for the methanolic extracts of palm oils from mode 1 (19.5–102.8 μmol TE/100 g and 18.8–103.0 μmol TE/100 g) were lower than for oils from mode 2 (25.6–134.8 μmol TE/100 g and 25.4–135.4 μmol TE/100 g). The total phenolics (4.1–12.4 mg GA/100 g) and carotenoids (0.18–45.8 mg/100 g) in the studied oils were correlated with their antioxidant capacities determined by FRAP and DPPH methods (r = 0.6623–0.9878). During the refining process, for both technological modes resulted in a loss of AC by 80%, TPC by 26–55% and TCC by 99%. The bleaching step caused the highest losses of AC as determined by FRAP 41% and 46%, DPPH by 43% and 48%, while TPC loss was 45% and 23% and loss of carotenoids was 49% and 56%, in mode 1 and mode 2, respectively.