Journal of Food Composition and Analysis 23 (2010) 346–352
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Original Article
Content and bioaccessibility of carotenoids from organic and non-organic baby foods M.A. Jiwan, P. Duane, L. O’Sullivan, N.M. O’Brien, S.A. Aherne * Department of Food and Nutritional Sciences, University College Cork, Western Road, Cork, Ireland
A R T I C L E I N F O
A B S T R A C T
Article history: Received 7 November 2008 Received in revised form 28 August 2009 Accepted 31 December 2009
Although organic baby foods are assumed to be more nutritious than their conventional counterparts, research data in this area are limited and equivocal. The objectives of the present study were first, to determine the carotenoid content of organic and non-organic baby foods; and, second, to analyze the bioaccessibility of carotenoids from these products. The baby foods selected for analysis were for the same age group (4+ months) and of two types: chicken and vegetable dinners and berry-based desserts. All foods were subjected to an in vitro digestion procedure which simulates gastrointestinal digestion. Due to their ingredient composition, carotenoid content and bioaccessibility varied within and between the organic and non-organic foods. In general, the non-organic berry-based desserts contained more carotenoids than the organic type. Although the carotenoids had a greater % bioaccessibility from the desserts than the dinners, the chicken and vegetable meals provided significantly higher amounts of carotenoids. Our findings show that carotenoid content reflects the ingredient composition of the baby meals. Therefore, the organic dinners tested were generally not superior to the non-organic foods in terms of carotenoid content and bioaccessibility. ß 2010 Elsevier Inc. All rights reserved.
Keywords: Baby food Bioaccessibility Carotenoids In vitro digestion Micellarization Organic Non-organic Provitamin A Food analysis Food composition
1. Introduction The demand for and popularity of organic food are on the rise internationally. Organic fruit and vegetables have been the topselling food group in the US, accounting for 43% of all US organic food sales in 2002 (Lester et al., 2007). On a European level, organic sales in the UK have risen 10-fold in the last 10 years. In Ireland, organic sales have increased by 82% since 2006 (Bord Bia, 2008). Although many consumers consider organic foods to be more nutritious than conventional (non-organic) foods, reviews of the literature have failed to draw definitive conclusions (Bourn and Prescott, 2002; Woese et al., 1997). Commercially available vegetable-based baby foods are a source of provitamin A carotenoids (including a-carotene, bcarotene and b-cryptoxanthin) as well as non-provitamin A carotenoids such as lutein, zeaxanthin, and lycopene. As their name suggests, provitamin A carotenoids are precursors – and thus good sources – of vitamin A (Strobel et al., 2007; Tang and Russell, 2004). However, they are also capable of exerting other important biologically active effects (Rock, 1997; Stahl and Sies, 2005). Nonprovitamin A carotenoids possess various bioactive properties
* Corresponding author. Tel.: +353 21 4902496; fax: +353 21 4270244. E-mail address:
[email protected] (S.A. Aherne). 0889-1575/$ – see front matter ß 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.jfca.2009.12.014
such as antioxidant activity, cell signaling activity, and potential protection against age-related macular degeneration (Rao and Rao, 2007; Rock, 1997; Sierksma et al., 1998; Stahl and Sies, 2005). Between the ages of 4 and 6 months, babies’ nutrient requirements increase dramatically, and consequently consumption of baby food products in addition to milk is required (Majchrzak et al., 2000). Organic baby food now accounts for almost half of baby food bought worldwide, even though research data on the nutritional benefits to babies of consuming organic foods compared with their non-organic counterparts are scarce and/or conflicting (Koh et al., 2008; Lester et al., 2007). To increase our knowledge on the amounts of carotenoids that are potentially available for absorption by babies from commercially available organic and non-organic baby foods, carotenoid bioavailability from these food products should be investigated. Bioavailability is defined as the fraction of an ingested nutrient available for use in normal physiological functions and storage in the body (Jackson, 1997). In the past decade, in vitro digestion models for assessing carotenoid bioavailability and bioaccessibility from foods have been developed and well-established (Garrett et al., 1999a, 2000; Granado-Lorencio et al., 2007a). Carotenoid bioaccessibility, which is defined as the amount of the carotenoid(s) available for absorption in the gut after digestion (DhuiqueMayer et al., 2007; Thakkar et al., 2007), has been of recent research interest. In addition, the efficiency of carotenoid micellarization,
M.A. Jiwan et al. / Journal of Food Composition and Analysis 23 (2010) 346–352
i.e. the transfer of carotenoids from the digestate (digested food) to the micelle (aqueous) fraction, is of particular importance as it is a good indicator of carotenoid bioavailability (Garrett et al., 2000; Hornero-Me´ndez and Mı´nguez-Mosquera, 2007). Therefore, the objectives of the present study were: first, to determine the carotenoid content of commercially available organic and non-organic baby food products; and second, to analyze the bioaccessibility of carotenoids from these food products. Only a few carotenoids are absorbed in sufficient quantities by human intestinal cells, which in turn can be detected in human plasma (Khachik et al., 1992), the most abundant being a-carotene, b-carotene, lycopene, b-cryptoxanthin, lutein, and zeaxanthin. In the present study, two provitamin A carotenoids, namely b-carotene and b-cryptoxanthin, as well as three nonprovitamin A carotenoids, zeaxanthin, lutein and lycopene, were analyzed. 2. Materials and methods 2.1. Materials
b-Cryptoxanthin (>95% purity) was purchased from LGC Prochem (Middlesex, UK). All other reagents including Hank’s Balanced Salts solution (HBSS), b-carotene (95% purity), lycopene (90–95% purity), lutein (90% purity, Fluka), zeaxanthin (95% purity, Fluka), and cholesterol esterase (Fluka) were purchased from Sigma–Aldrich Chemicals Co. (Dublin, Ireland). 2.2. Sample preparation Both organic and non-organic baby foods were purchased from the same supermarket chain, at the same location, on the same day of each week. Each lot number represented one sample, and the number of samples tested is equal to the number of independent experiments as reported in the tables. Since the manufacture of baby food products is a tightly controlled process, variability between lots is assumed to be minimal (Brooks et al., 2006). The baby foods were purchased over a 3-month period and were analyzed well within their expiry and storage dates. Four organic and five non-organic baby foods for the same age group (4+ months) and of two types were selected: chicken and vegetable dinners and berry-based desserts. Baby foods from only three leading baby food companies were available for purchase; therefore these were the ones used in the study and the analysis was representative of the range of flavors available to consumers. The ingredients and nutritional composition of each baby food product, which appeared on the product labels, is provided in Table 1. The food jars were stored unopened in a cupboard until the day of the experiment. All manipulations with the foods were conducted under subdued (yellow) light to minimize photodegradation of the carotenoids. The organic chicken and vegetable dinners were labeled A, B and C, with B and C manufactured by the same food company. The organic berry-based dessert was labeled D. The non-organic chicken and vegetable dinners were labeled E, F and G, with E and F produced by the same food company. The foods H and I were two nonorganic berry-based desserts. 2.3. In vitro digestion procedure The in vitro digestion model was performed using the method of Garrett et al. (1999a,b) with minor modifications as previously described (Ryan et al., 2008). Samples were accurately weighed (2 g) and homogenized in 5 mL HBSS. Digestion was carried out by acidifying the samples to pH 2 using porcine pepsin (0.04 g/mL
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HCl) followed by incubation at 37 8C in a Grant OLS 200 orbital shaking water bath (Grant Instruments, Cambridge, UK) for 1 h. After gastric digestion, pH was increased to 5.3 with 0.9 M sodium bicarbonate, followed by the addition of glycodeoxycholate (0.80 mM final concentration), taurodeoxycholate (0.45 mM final concentration), taurocholate (0.75 mM final concentration), pancreatin (0.08 g/mL) and cholesterol esterase (1 U/mL). The pH of each sample was increased to 7.4, followed by incubation at 37 8C for 2 h in the orbital shaking water bath. The final volume of the digesta was ca. 20 mL. After the intestinal phase, 5 mL of the digesta were stored at 80 8C, after overlaying with nitrogen gas, until further analysis. The remainder of the digesta was ultracentrifuged (Beckman L7-65 ultracentrifuge, Palo Alto, CA, USA) at 53,000 rpm for 95 min at 4 8C to isolate the micelle (aqueous) fraction. The resulting supernatant was collected with a syringe and filter-sterilized using a surfactant free cellulose acetate filter (0.2 mm; Millipore, Bedford, MA, USA) to remove any microcrystalline aggregates. Samples were stored at 80 8C, after overlaying the headspace with nitrogen gas, until further analysis. 2.4. Extraction and HPLC procedure Carotenoid extraction was carried out according to the method of Olives Barba et al. (2006) as previously described (Ryan et al., 2008). To enable better chromatographic separation and detection of the carotenoids, the samples were saponified using a simple procedure according to the method of Granado et al. (2001), as previously described by O’Sullivan et al. (2008a). The inclusion of this step does not result in any loss of carotenoid content (O’Sullivan et al., 2008a). The saponified extracts were dried under nitrogen and frozen at 80 8C. HPLC analysis was performed by the method of Hart and Scott (1995), as previously described (O’Sullivan et al., 2008b; Ryan et al., 2008). Briefly, samples were re-constituted in 200 ml of mobile phase and carotenoid content was quantified by reverse-phase HPLC (Shimadzu, Kyoto, Japan) which consisted of a LC10-AD pump connected to a SIL-10A autoinjector and SPD-10AV UV–vis detector. Two 250 mm 4.6 mm Vydac 201TP54 C18 columns (5 mm, 300 A˚; Grace Davison Discovery Sciences, IL, US) were maintained at 30 8C. The flow rate was 1.5 mL/min and detection was carried out at 450 nm for the carotenoids. Lutein, b-cryptoxanthin, b-carotene, zeaxanthin and lycopene levels in the samples were extrapolated from carotenoid standard curves, after correction for extraction efficiency based on the recovery standard which was added during the extraction phase (96–100% recovery range). The intraassay variation for the carotenoids tested was 3–6% and inter-assay variability was
