Bioaccessibility of carotenes from carrots: Effect of cooking and addition of oil

Food processing and occurrence of dietary lipids are believed to be important and limiting factors for carotenoid bioavailability in humans. In the present study the isolated and combined effects of household cooking and addition of olive oil on the bioaccessibility of carotenes from carrots have been investigated. Although thermal treatment during cooking showed to have a negative impact on the carotenoid content, a positive effect on the micellarisation of carotenes and therefore on their bioaccessibility was found. Carotenes transferred to the digests were micellarised to a higher extent from cooked carrots (52%) than from crude carrots (29%). Addition of olive oil to carrot samples during cooking and before application of the in vitro digestion model had a marked positive effect on the release of carotenes, although the design of the model did not allow the correct estimation of this effect. The higher amounts of micellarised carotenes (80%) were found in the digest prepared from cooked carrots containing 10% olive oil. In general, the inclusion of olive oil during cooking increased the carotenoid extraction and micellarisation in a dose-dependent fashion. Although β-carotene and α-carotene were affected in a similar way by the cooking process, α-carotene appeared to be more efficiently incorporated into the micelles when olive oil was added to the samples. In conclusion, both processing and mainly lipid content (cooking oil in this case) significantly improve carotenoid bioaccessibility from carrots, and therefore may increase bioavailability in humans.Industrial relevanceThe consumption of carotenoid-rich foods such as fruits and vegetables has been associated with a decrease of the risk of developing certain types of degenerative and chronic diseases. Processing of food and the interaction of carotenoids with lipophilic food components or ingredients may modify the amount of the released pigment from the food matrix, and therefore potentially increase or decrease their bioavailability. For this purpose, in the present study we have investigated the effects of cooking and presence of olive oil on the release of carotenes from carrots (as a model food) and their incorporation into absorbable micelles, the bioaccessibility. From the industrial point of view, a better understanding of the factors governing the release of carotenoids and other active components from vegetable foods is of great importance with the aim of optimising the manufacturing processes.     

Bioavailability of β-carotene isomers from raw and cooked carrots using an in vitro digestion model coupled with a human intestinal Caco-2 cell model

Not only is there limited information in the literature regarding the β-carotene (BC) isomer profile of micelles from digested foods; few studies have looked at their subsequent uptake and transport by human intestinal Caco-2 cells. Therefore, the aims of the present study were, first, to assess the profile of BC isomers in micelles from digested raw and cooked carrots; and, second, to determine their cellular uptake and transport. Greater amounts of all-trans-, 13-cis- and 15-cis-BC isomers were present in the micelles of cooked carrots compared with raw carrots. Furthermore, micelle fractions obtained from the most highly processed (pureed) carrots had greater (P < 0.05) amounts of all-trans-, 13-cis- and 15-cis-BC compared with those derived from raw and boiled carrots. A similar trend was seen with BC isomer uptake and transport. Our data suggest that the food matrix and degree of processing play important roles on carotenoid isomerization and bioavailability.     

Carrot Pulp Chemical Composition, Color, and Water-holding Capacity as Affected by Blanching

Our objectives were to investigate the effect of blanching on nutrients, color, α- and β-carotenes, dietary fiber, and water-holding capacity of carrot pulp after juice was extracted. Carrot pulp contained 4-5% protein, 8-9% reducing sugars, and 5-6% minerals. Compared to the color of fresh carrot juice, pulp from blanched carrots retained redness color values better than that from unblanched carrots. Pulp contained from unblanched: 17% and from blanched: 31-35% of the total α- and β carotenes in the fresh carrots. Glucose and galacturonic acid were predominant sugars of the nonstarchy polysaccharides (NSP) in carrots. Pulp contained 37-48% total dietary fiber and had a high water-holding capacity (WHC), ranging from 9.42 to 10.52g water/g organic matter. Considering carotenes, WHC, and fiber content, carrot pulp products are a good source of dietary fiber.     

再造型胡萝卜复合脆片中类胡萝卜素生物利用度

以再造型胡萝卜复合脆片、胡萝卜脆片、胡萝卜鲜样为对象,通过体外模拟消化,探究加工方式与口腔咀嚼程度（咀嚼5、15?次和30?次）对样品的消化特性以及类胡萝卜素生物利用度的影响。结果显示：在消化过程中,胡萝卜鲜样和脆片的消化液平均粒径大小均有显著性差异（P＜0.05）;随着咀嚼程度增大,胡萝卜脆片的消化液平均粒径逐渐变大,说明咀嚼后悬浮于消化液中的颗粒数量越多,越容易产生絮凝作用。共聚焦显微镜观察发现,在口腔阶段,消化液中的油脂与样品结合形成较大的聚集体;经过胃消化后,脂滴逐渐分散到消化液中;经过小肠消化后油脂被消化分解,与类胡萝卜素形成胶束,胶束的数量多少决定着类胡萝卜素生物利用度的高低。胡萝卜鲜样的类胡萝卜素含量最高,但生物利用度最低;再造型胡萝卜复合脆片的类胡萝卜素含量较低,但其生物利用度较高,且咀嚼程度对再造型胡萝卜复合脆片的生物利用度无显著影响（P＞0.05）。综上所述,再造型胡萝卜复合脆片消化特性较好,并且具有较高的类胡萝卜素生物利用度,可作为一种有效补充类胡萝卜素的果蔬休闲食品。     

The Effect of Endogenous Pectinases on the Consistency of Tomato–Carrot Purée Mixes

Tomato and carrot were subjected to a split-stream process designed to produce a tomato–carrot suspension with reduced consistency. Raw tomatoes, containing pectinmethylesterase and endo-polygalacturonase, were mixed with thermally pretreated (blanched versus cooked) carrots containing different levels of solubilized pectin. After mixing the vegetables, tomato pectinases were shown to act on both tomato and carrot pectin in case an incubation step at medium temperature level (30 min, 40 °C), to allow enzyme action, was performed. Carrot pectin, when present in a mix of tomato and blanched (5 min, 95 °C) carrot, was solubilized as well as depolymerized, whereas depolymerization of the thermo-solubilized carrot pectin by the tomato pectinases was observed in the tomato–carrot purée containing cooked (30 min, 95 °C) carrots. The final serum pectin properties were however similar for both purée types. Carrot contributed more to the consistency of the purée mix compared with tomato but by stimulating the action of the tomato pectinases at mild temperature (30 min, 40 °C), this contribution was lost which resulted in a consistency reduction of the purée mix. This purée liquefaction was larger for the tomato–carrot purée containing blanched instead of cooked carrots. Based on the results, it is suggested that the liquefying effect is related to solubilization and degradation of pectin that is counteracted by a reduction in particle size. The purée mix containing cooked carrot showed in this respect smaller particle sizes than the mix containing blanched carrot.     

Frozen Carrots Texture and Pectic Compotients as Affected by Low-Temperature-Blanching and Quick Freezing

Carrots preheated for 2 hr at 60°C and then cooked became firmer than raw or cooked carrots. After preheating, the amount of high methoxyl pectin decreased, and low methoxyl pectin increased. Firmness of carrots decreased through freezing then thawing, but preheated carrots retained firmer texture than those blanched in boiling water. Quick-freezing resulted in better texture than slow-freezing. Loss in texture was accompanied by release of pectin. Slow-freezing accelerated release of pectin as compared to quick-freezing. Preheated carrots were slower in release of pectin. The degree of esterification of pectin substances in raw carrots decreased during preheating, freezing and thawing. Cell damage in quick frozen carrots was slight. Optimum preheating occurred with 30 min at 60°C or 5 min at 70°C. Preheating and then quick freezing were effective in improving texture of frozen carrots.     

High pressure homogenization increases the in vitro bioaccessibility of α- and β-carotene in carrot emulsions but not of lycopene in tomato emulsions

Abstract: The correlation between food microstructure and in vitro bioaccessibility of carotenes was evaluated for tomato and carrot emulsions (5% olive oil) subjected to high pressure homogenization (HPH) at varying degrees of intensity. The aim was to investigate whether additional mechanical disruption of the food matrix could be utilized to further increase the carotene bioaccessibility of an already pre‐processed material. The carotene bioaccessibility of the samples was measured after simulated in vitro digestion, carotene release to the oil phase was estimated by Confocal Raman spectroscopy and, to measure active uptake of carotenes, Caco‐2 cells were incubated with the digesta of selected samples. HPH did not notably affect the retention of carotenes or ascorbic acid but significantly increased both the release and micellar incorporation of α‐ and β‐carotene in carrot emulsions 1.5‐ to 1.6‐fold. On the other hand, in vitro bioaccessibility of lycopene from tomato was not increased by HPH under any of the conditions investigated. Instead, the results suggested that lycopene bioaccessibility was limited by a combination of the low solubility of lycopene in dietary lipids and entrapment in the cellular network. Carotene uptake by Caco‐2 cells appeared to be mainly dependent upon the carotene concentration of the digesta, but cis‐trans isomerization had a significant impact on the micellarization efficiency of carotenes. We therefore conclude that HPH is an interesting option for increasing the bioaccessibility of carotenes from fruits and vegetables while maintaining a high nutrient content, but that the results will depend on both food source and type of carotene. Practical Application: A better understanding of the correlation between the processing of fruits and vegetables, microstructure and nutrient bioaccessibility can be directly applied in the production of food products with an increased nutritional value.     

Bioactivity of falcarinol and the influenceof processing and storage on its content in carrots (Daucus carota L)

The concentration‐dependent activity of the polyacetylene falcarinol ((9Z)‐heptadeca‐1,9‐dien‐4,6‐diyn‐3‐ol), isolated from carrots, was investigated in a bioassay with primary mammary epithelial cells in collagen gels and compared with that of β‐carotene, the orange pigment in carrots. Falcarinol showed biphasic activity, having stimulatory effects between 0.01 and 0.05 µg ml^?1 and inhibitory effects between 1 and 10 µg ml^?1, whereas β‐carotene showed no effect in the concentration range 0.001–100 µg ml^?1. The results are discussed in relation to the health‐promoting effects of carrots and related vegetables. Falcarinol was quantified in the carrot cultivars Bolero, Rodelika and Fancy by analytical reverse phase HPLC, subjected to various processing and storage conditions in order to study how long‐term storage, blanching, freezing and boiling influence the content of falcarinol. Long‐term storage of raw carrot cubes (1 cm³) reduced the falcarinol content by almost 35%. A similar reduction was found in steam‐blanched carrot cubes (1 cm³). Long‐term storage at ?24 °C of steam blanched carrot cubes did not reduce the falcarinol content further. A reduction of almost 70% in the falcarinol content was found in carrot pieces boiled in water for 12 min compared with raw carrots. Copyright © 2003 Society of Chemical Industry     

The influence of milk with different compositions on the bioavailability of blackberry polyphenols in model sports nutrition beverages

This study aimed to determine whether the fat and protein content in dairy-fruit blends prepared using full-fat, semi-skimmed, skimmed or high-protein milk in combination with freeze-dried blackberry puree influenced the bioaccessibility and bioavailability of blackberry polyphenols and organic acids. Samples were subjected to in vitro digestion, after which bioavailability was analysed with a Caco-2 cell model. The addition of puree to milk resulted in the formation of protein aggregates, which partially protected anthocyanins during digestion. Milk fat may have increased the bioaccessibility of anthocyanins while reducing permeability through the Caco-2 cells, leading to a lower bioavailability in tested samples.     

基于体外模拟消化/Caco-2细胞模型测定大米中铅的生物有效性

为考察铅污染大米对人体的潜在健康风险,研究建立体外模拟消化/Caco-2细胞模型来测定大米中铅的生物有效性。结果表明：在模拟大米中铅的胃肠消化过程中,生米和熟米在胃消化阶段铅的生物利用率为61.34%～70.59%和39.69%～47.48%,肠消化阶段分别为24.39%～41.79%和13.57%～15.13%,经胃肠消化后籼米中铅的生物利用率均高于粳米,生米经胃、肠消化生物有效性程度均高于蒸煮后的大米。建立并利用成熟Caco-2细胞模型对大米中铅的生物有效性进行测定,使用四乙基铅与无机铅对大米加标,生米的生物有效性为3.32%和7.0%,熟米的生物有效性为2.65%和5.7%。体外模拟消化/Caco-2细胞模型是一种评价大米中铅生物有效性的有效手段。     

Carrot Juice Color, Carotenoids, and Nonstarchy Polysaccharides as Affected by Processing Conditions

Effects of processing variables on color, α- and β-carotenes, and non-starchy polysaccharides (NSP) of carrot juice products were investigated. Unblanched‘carrots produced the highest amounts of juice and lowest amounts of pulp. Compared to color of fresh juice, canned juice from acetic acid-blanched carrots retained redness best, and juice from unblanched carrots retained the least. Juice products from unblanched carrots retained highest total carotenes. Retorting, concentrating, and freeze-drying partly reduced juice product carotenes. In most cases, the reduced amounts from various processing methods were greater for β-carotene than for α-carotene. NSP contents of juice products ranged from 1.1 to 1.5%.     

ULTRASTRUCTURAL AND TEXTURAL CHANGES IN PROCESSED CARROT TISSUE1

Processed carrot tissues were studied using a transmission electron microscope (TEM) and an Instron Universal Testing Instrument. Carrot slices were evaluated raw, after thermal processing and after freezing and thawing. Cell walls of carrot tissues, frozen and thawed, were intact and dense. The middle lamella lost pectic materials. Overall, frozen and thawed cells were not so closely pressed as those of raw tissues. In thermally processed carrots the cell wall and the middle lamella were less densely stained compared to raw or frozen-thawed carrots. Thermally processed carrots exhibited significantly smaller modulus of deformability and stiffness and toughness values than raw carrots. There were no significant differences between the modulus of deformability and stiffness values for frozen-thawed and thermally processed carrots. Toughness values were, however, significantly lower for the thermally processed in comparison with the frozen-thawed carrots. Instrumental texture measurements indicated that different areas of carrot tissue behave differently to thermal processing.     

Effect of high pressure processing on microbiological and physical qualities of carrot and spinach

This study was designed to evaluate the microbiological and physicochemical properties of carrot and spinach treated at 100, 300, and 500 MPa for 20 min. The numbers of Salmonella Typhimurium cells were significantly reduced by more than 5 log CFU/g in carrots and spinaches treated at 500 MPa after 5 min. The color changes were noticeable in the cooked carrots (ΔE>9) and spinaches (ΔE>12). Two distinct phases were observed in the textural changes of carrots and spinaches under high pressure processing. These results provide useful information for understanding microbial inactivation, color changes, and textural properties in high pressure-treated carrot and spinach samples.     

Influence of the design of a product on in vitro mineral availability of homogenized weaning foods

The influence of the design of the product (percentage of main ingredients used in the formulation of the product) on mineral content and their ‘in vitro’ bioavailability, such as total dietary fibre (TDF) and phytic acid (PA) of a meat-based infant weaning food was studied. Phosphorus, Ca, Zn and Fe concentration and ‘in vitro’ availability of Ca, Fe and Zn changed depending on the percentage of rice flour, carrot, pea puree and chicken liver in the weaning foods. Also TDF contents depends on the design of the product, and both, FA and TDF, reduce the mineral bioavailability. Increasing pea puree and carrot in the formulation of the weaning food could increase P and Ca content. On the other hand, carrot supplies high TDF, therefore contributing to reduction of Ca availability. Iron content was positively correlated with the percentage of chicken liver. Percentage of carrot and pea puree included in the formulation of the weaning foods analysed determined the differences in Fe availability as significant positive regression coefficients (b=0.676, P<0.05 and b=0.622, P<0.05, respectively) were found. Using the in vitro availability values we have performed Cluster analysis and principal components analysis (PCA) to establish the best combination of percentages of raw ingredient which provides the highest mineral availability.     

Potential of front face fluorescence as a monitoring tool of neoformed compounds in industrially processed carrot baby food

The aim of this study was to evaluate the potential of using front face fluorescence (FFF) to monitor the impact of industrial process on carrot baby food, and to calibrate their content in neoformed compounds (NFC). Chromatographically measured NFC included furosine, carboxymethyllysine, and furan. The effect of using different raw material, fresh carrots, frozen cubes or pasteurized puree on NFC content in the resultant sterilized puree was also tested. Bidimensional FFF spectra acquired on the samples were decomposed using multiway PARAFAC model and used to predict the chromatographically measured NFC. FFF PARAFAC sample intensities systematically evolved with successive industrial process steps. The levels of NFC increased the most during heat treatment operations. Frozen cubes resulted in the purees with the lowest content in NFC, compared to fresh or pasteurized carrot cubes. Satisfactory calibration models (R² > 0.94) of the chromatographically measured NFC were obtained using FFF PARAFAC sample intensities as predictors. The multivariate regression models root mean square of cross validation for furosine, carboxymethyllysine, and furan were 3.98 mg/kg, 1.38 mg/kg and 5.23 µg/kg, respectively. From these first results we conclude that FFF is a promising tool to monitor fast and easily vegetable processing in a quality control approach.     

Towards a better understanding of the relationship between the β-carotene in vitro bio-accessibility and pectin structural changes: A case study on carrots

The quality of fruit and vegetables based products is affected by processing. Two important parameters to consider are the structural characteristics and the nutritional value. As pectin is a major constituent of plant cell walls, pectin structure engineering can be used as a tool to affect the structural quality of plant based food products. During thermal processing, pectin characteristics are influenced. Recently, it has been highlighted that nutrient bio-accessibility is affected by food structure. The intracellular localization of nutrients implies that their accessibility can be hindered by several structural elements.Therefore, this investigation focused on the relation between the structural quality and the nutritional value of carrots. Texture was measured as an indication for the structural quality, while the β-carotene in vitro bio-accessibility was selected as a parameter reflecting the nutritional value. The effect of thermal (pre)processing on this relationship was investigated. The results clearly indicate that the structural quality of carrots and the β-carotene in vitro bio-accessibility are inversely correlated. Moreover, it was hypothesized that pectin changes during thermal processing play a key role in this inverse relationship.     

Bioavailability of peptides from casein hydrolysate in vitro: Amino acid compositions of peptides affect the antioxidant efficacy and resistance to intestinal peptidases

Measurements of in vitro bioactivity to support health benefits of bioactive compounds should be accomplished with estimates of their bioavailability to bolster nutritional significance to health claims. In vitro bioavailability of casein and casein peptides (casein hydrolysate and four peptide fractions) measured by the amount of peptide nitrogen is discussed. Antioxidant activities during gastrointestinal digestion and Caco-2 cell absorption were investigated as indices of peptide degradation. The antioxidant capacities of Trolox equivalent and oxygen radicals were used for assessing antioxidant efficacy of surviving peptides. Results showed that casein hydrolysate improved bioavailability compared to casein. Amino acid composition of peptides affected the resistance of peptides to digestive enzymes and intestinal peptidases. The acidic peptide fractions had higher bioavailability and a higher residual ratio of antioxidant activity. The peptides in the digest and absorbate of acidic fraction F1 with the highest bioavailability (23.14%) and the residual ratio of antioxidant activity were identified, and 12 intact, absorbed peptides (IAP) were obtained. Eleven of twelve of the IAPs were from β-Casein, and their amino acid components were rich in acidic and hydrophobic amino acids. Identification of IAPs might provide insight into the mechanism of how peptide structure provides resistance against peptidases by Caco-2 cells.     

Method for the static headspace analysis of carrot volatiles

A static headspace analysis/gas chromatography/mass spectrometry (SHA/GC/MS) method was developed to analyse the volatile composition of raw (seven different varieties), stored and cooked carrot samples. A total of 35 different volatile compounds were identified in carrots. Of these, trans-ocimene, 2,5-dimethyl styrene, camphor, borneol, α-santalene, α-selinene, γ-elemene and α-zingiberene in raw carrots and propanol in stored carrots were identified for the first time. Major volatile compounds identified in raw carrots were α-pinene, sabinene, myrcene, limonene, γ-terpinene, terpinolene, β-caryophyllene and γ-bisabolene. Mono-and sesquiterpenes accounted for about 97% of the total volatiles identified. Sizeable varietal differences (p<0.01) were observed. Carrot volatiles did not change appreciably during the 28 day storage period at 5, 25 and 35°C, except propanol that showed exponential increases at higher temperatures. No propanol was detected in fresh raw carrots. Cooking resulted in 88.6, 93.0 and 95.5% loss in total volatiles after cooking times of 10, 20 and 30 min, respectively.     

Effects of low temperature blanching on texture,microstructure and rehydration capacity of carrots

The effect on quality of stepwise blanching (first 10 min at 65 °C, 50 min holding time, and 1 min at 95 °C) prior to drying of carrot slices was compared with conventional blanching (95 °C, 1 min). As quality parameters, rehydration capacity (effective diffusivity D_e, equilibrium moisture content W_e), texture (puncture test) and microstructure (SEM and Cryo‐SEM) were chosen. Non‐significant differences were found between the W_e of stepwise blanched samples and conventionally blanched ones, both values being similar to the moisture content of fresh carrots. D_e of conventional blanched carrots was higher than for stepwise blanched ones. Maximum force of stepwise blanched samples was higher than those of conventionally blanched ones and not significantly different from fresh carrots. Microstructural observations showed that stepwise blanching preserved cell to cell contacts better than conventional blanching; this fact was attributed to pectin‐methyl‐esterase activation at 65 °C, resulting in the differences in the maximum force between both treatments. Conventionally blanched samples tended to separate along their cell walls, forming voids among the phloem parenchyma cells. These voids would be filled with water during rehydration, thus showing the slightly higher W_e and the higher D_e for conventionally blanched carrots. Copyright © 2005 Society of Chemical Industry     

Effect of chickpea protein hydrolysates on cell proliferation and in vitro bioavailability

Bioactive peptides in foods may have health-promoting properties, including effects on cell proliferation. The goal of this study was to determine whether physiological digestion of chickpea protein using pepsin and pancreatin could release this type of peptides. The THP-1 and Caco-2 cell lines were used as in vitro models to determine the effects of the hydrolysates on cell proliferation. Hydrolysates with a high degree of hydrolysis inhibited the growth of Caco-2 cells by up to 45%, suggesting that chickpea-derived peptides might inhibit the growth of tumors in the colon. Proliferation of THP-1 cells was inhibited by up to 78% by direct exposure to the hydrolysates. Nevertheless, bioavailability experiments using differentiated Caco-2 cells as a model of the intestinal barrier, in co-culture with THP-1 cells, showed that proliferation of the monocytic THP-1 cells was actually enhanced by up to 66%, which could represent an immunomodulatory activity.