Elsevier

Food Chemistry

Volume 141, Issue 3, 1 December 2013, Pages 2606-2613
Food Chemistry

The effect of domestic processing on the content and bioaccessibility of carotenoids from chili peppers (Capsicum species)

https://doi.org/10.1016/j.foodchem.2013.05.046Get rights and content

Highlights

  • Content and bioaccessibility of carotenoids from chili peppers were investigated.

  • Peppers were analysed before and after boiling and following a freezing period.

  • Carotenoids content and bioaccessibility varied on cultivar, colour and processing.

  • Bioaccessibility of carotenoids is enhanced by process.

Abstract

The content and bioaccessibility of carotenoids from different chili peppers were analysed and the effects of typical domestic processing were investigated. Peppers were analysed before and after cooking by conventional boiling (10 min in 100 °C water) and also following a freezing period of four months in a domestic freezer (−20 °C). The content and bioaccessibility of the eight carotenoids quantified varied, depending on cultivar, species, colour and processing. Provitamin A carotenoids (β-carotene and β-cryptoxanthin) and capsanthin were present at highest concentrations in the samples before and after processing. In general, yellow and orange peppers were the best sources of lutein, zeaxanthin and neoxanthin. Xanthophyll carotenoids were more efficiently transferred to the micelles and, therefore, were also more bioavailable. Processing decreased the carotenoid content in certain samples; however, the micellar content was generally not lower for processed peppers; therefore the bioaccessibility of carotenoids from processed peppers is enhanced relative to unprocessed peppers.

Introduction

Chili peppers are an indispensable spice, used as a basic ingredient in a great variety of cuisines all over the world. They are also used as flavourings, colorants and add tang and taste to otherwise insipid foods. Peppers have been the subject of study, mainly as a source of capsaicin, which produces different pungency levels (Oboh, Puntel, & Rocha, 2007), as well as carotenoids and phenolic compounds, which are used as natural pigments and antioxidant agents (Suna, Youl Ha, & Park, 2008). The concentrations and composition of carotenoids are responsible for the diverse and attractive colours observed in peppers (Howard, 2001). Chlorophyll contributes to the green colour (Marin, Ferreres, Tomas-Barberan, & Gil, 2004), α- and β-carotene, zeaxanthin, lutein and β-cryptoxanthin to the yellow–orange colour (Howard, 2001), whereas red-pigmented chili peppers are the result from the presence of capsanthin and capsorubin (Matsufuji, Nakamura, Chino, & Takeda, 1998).

The colour of each Capsicum variety in the full-ripe stage depends on its capacity for synthesising carotenoids and even for retaining chlorophyll pigments. In fact, variety is an important factor, determining both the composition and content of plant pigments (Guil-Guerrero & Rebolloso-Fuentes, 2009).

The genus Capsicum is classified into the family of Solanaceae and is comprised of 25 wild and five domesticated species (C. annuum L., C. frutescens L., C. chinense Jacq, C. baccatum Jacq, and C. pubescens L.), which include more than 200 varieties (Conforti, Statti, & Menichini, 2007), only a few of which have been studied in detail.

The purported health benefits of peppers have been attributed, in part, to their carotenoid content. In fact these fat-soluble compounds have been shown to protect against certain cancers, prevent gastric ulcers, stimulate the immune system, protect against cardio-vascular diseases and age-related macular degeneration and cataracts (Krinsky & Johnson, 2005).

In the Mediterranean diet, chili peppers are largely eaten in raw, cooked, or processed forms. Typical processing methods include freezing of the pepper, in order to store the fruit for a longer period. These processes may influence the content and bioaccessibility of the carotenoids contained in food.

Bioaccessibility is defined as the amount of an ingested nutrient that is available for absorption in the gut after digestion (Hedren, Diaz, & Svanberg, 2002). It is possible to determine the bioaccessibility of a carotenoid by measuring the quantity transferred to the micelle fraction following a simulated in vitro digestion procedure (Jiwan, Duane, O’Sullivan, O’Brien, & Aherne, 2010). The micelle fraction is isolated by ultracentrifugation of the digested samples. This method is suitable for the routine screening of plant foods for carotenoid bioaccessibility and may be used as an indicator of potential bioavailability (Garrett, Failla, & Sarama, 2000). Previous studies have reported the effect of processing on the carotenoid content of vegetables (Nunn et al., 2006, Ryan et al., 2008). However, information on the effects of processing on content and bioaccessibility of carotenoids from peppers is limited.

The objective of the present study was to investigate the effect of different processing treatments (freezing and boiling) on the composition and bioaccessibility of carotenoids from seven varieties of coloured (orange, red and yellow) peppers belonging to different species (C. annum, C. chinense, C. baccatum, C. chacoense).

Section snippets

Chemicals, reagents and instruments

All reagents, including Hank’s Balanced Salts solution (HBSS), lutein, capsanthin, zeaxanthin, β-carotene, β-apo-8′-carotenal and cholesterol esterase were purchased from Sigma–Aldrich Chemical Co. (Dublin, Ireland). β-Cryptoxanthin, violaxanthin, neoxanthin and antheraxanthin were purchased from LGC Prochem (Middlesex, UK). All solvents employed were of HPLC grade. An Ultra-Turrax T25 homogeniser, (IKA-Labortechnik, Staufen, Germany), Sorvall TC6 centrifuge (DuPont Instruments, Herts, UK),

Carotenoid contents in chili peppers

The carotenoid contents of the pepper varieties (Table 1) are listed in Table 2, Table 3. Capsanthin was one of the predominant carotenoids in red peppers, with contents ranging from 230 to 848 μg/100 g pepper. Sample P7 also contained capsanthin at an appreciable level (104 μg/100 g). There was no capsanthin detectable in raw or frozen yellow pepper (P1) or in the raw or frozen orange pepper (P5). Similarly, no capsanthin was detectable in boiled P5. However, in the boiled P1 samples, a small

Discussion

Studies have associated the health benefits of consuming fruits and vegetables rich in carotenoids with a reduced risk of human chronic diseases (Rao & Rao, 2007), but it is known that the absorption of these compounds may be highly variable (Faulks & Southon, 2005). It is possible to determine the proportion of a nutrient which is available for intestinal absorption by studying the transfer of the compound from the food matrix to the mixed micelles. This transfer is defined as bioaccessibility

Conclusion

This study was conducted to investigate the effects of different processing methods (domestic freezing or boiling) on the carotenoid composition of seven varieties of coloured peppers. Red, orange and yellow peppers were confirmed to be good sources of carotenoids. Gaining knowledge on the effects of cooking and processing on carotenoid-containing foods facilitates the optimisation of carotenoid bioavailability for food manufacturers and helps consumers obtain adequate intakes of carotenoids.

References (37)

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