Particle Size Reduction Leading to Cell Wall Rupture Is More Important for the β-Carotene Bioaccessibility of Raw Compared to Thermally Processed Carrots

Abstract

The amount of nutrients that can be released from food products (i.e., nutrient in vitro bioaccessibility) is often studied as it is a starting point for investigating nutrient bioavailability, an indicator for the nutritional value of food products. However, the importance of mastication as a particle size reduction technique is poorly understood and is often neglected during in vitro procedures determining bioaccessibility. Therefore, the aim of the present work was to study the effect of mechanical breakdown on the β-carotene bioaccessibility of carrot samples, having different textural/structural characteristics (as a result of thermal processing). In the first part of this study, the all-E-β-carotene bioaccessibility of carrot particles of different sizes (ranging from cell fragments up to large cell clusters), generated from raw as well as from gently and intensely cooked carrot samples, was determined. In the second part of the study, the effect of human mastication on the particle size reduction of raw as well as of gently and intensely cooked carrot samples was investigated in order to allow identification and validation of a technique that could mimic mastication during in vitro procedures. Results showed a strong dependency of the all-E-β-carotene bioaccessibility on the particle size for raw and gently cooked carrots. After intense cooking, on the other hand, a considerable amount of all-E-β-carotene could be released from cell fragments (smaller than a cell) as well as from small and large cell clusters. Hence, the importance of mechanical breakdown, and thus also of (in vitro) mastication, is dependent on the carrot sample that is considered (i.e., the extent to which the carrot sample has been thermally processed prior to the particle size reduction). Structural changes occurring during mechanical and thermal processing are hereby key factors determining the all-E-β-carotene bioaccessibility. The average particle size distribution curves of raw and cooked carrots, which were chewed by 15 persons, could be mimicked by mixing 50 g of carrots using a Grindomix (Retsch) at 2500 rpm during 5 s. Based on this scientific knowledge, the identified in vitro mastication technique was successfully integrated in the in vitro digestion procedure determining the all-E-β-carotene bioaccessibility of carrot samples.

Carotenoid Deposition in Plant And Animal Foods and Its Impact on Bioavailability

“…To the best of our knowledge, evidence from human trials for this observation is lacking. In agreement with Lemmens et al (2010), Netzel et al (2011) reported the highest release of carotenes from cooked carrots when compared …”

“…For example, Lemmens et al (2010) showed a strong positive correlation of a more intense mastication with an enhanced in vitro carotenoid bioaccessibility from raw, fresh carrots. After rigorous cooking of the carrots, the specific dependency of β-carotene bioaccessibility on mastication of the carrot tissue disappeared.…”

Bioactive Compound Encapsulation and Its Behavior duringIn VitroDigestion

“…The particle size obtained during chewing has been studied to understand the effect of the particle size on nutrient release during the later steps in digestion. Similar effects have been reported for other type of nutrients such as β-carotene, as demonstrated by the study performed by Lemmens et al (2010), who evaluated the effect of the particle size on β-carotene bioaccessibility from raw and thermally processed carrots. This situation was clearly observed in rice where in vitro digestion of whole and chewed rice resulted in significant differences in the glucose release rate, with a lower glucose release for whole grain and a higher release when the particle size was smaller than 1000 μm.…”

Application of in vitro bioaccessibility and bioavailability methods for calcium, carotenoids, folate, iron, magnesium, polyphenols, zinc, and vitamins B6, B12, D, and E

“…The residue, containing the released carotenoids, is dissolved in a mobile phase solvent (consisting of methanol, methyl-t-butyl ether, and water) and filtered through a 0.45 μm pore size cellulose membrane filter and subjected to reverse phase HPLC. This method has been used after minor modifications to study the effects of thermal processing (Lemmens et al, 2011) and particle size (Lemmens et al, 2010) on β-carotene bioaccessibility from carrots.…”