Impact of Processing of Biofortified Cassava and Peach Palm Fruits on Pro-vitamin A Carotenoid Recovery and Bioaccessibility
Increasing nutritional value in staple crops via conventional breeding or genetic transformation has resulted in an integrative strategy of supplementation and fortification to alleviate nutritional deficiencies from high-risk populations. For instance, biofortification programs in staple crops such as cassava have successfully improved pro-vitamin A carotenoid (pVAC) levels by achieving contents up to 25 µg/g FW, exceeding the target value of 15 µg/g FW. However, incorporation of biofortified cassava genotypes into traditional and industrial processing has yet to be thoroughly evaluated. An alternative to biofortified crops is the leveraging of under-utilized micronutrient dense native plants. For example, fruits from peach palm trees (Bactris gasipaes), native to South America, have a total carotenoid content (TCC) ~198 µg/g FW (~70% pVAC) and could be better utilized to address vitamin A deficiencies. However, these fruits are poorly commercialized even in their countries of origin, and the impact of processing on carotenoids stability has been scarcely assessed. Translation of biofortified crops and native fruits into consumer products have the potential to address micronutrient deficiencies in high-risk populations. However, fundamental work to address genotypic differences and impacts of traditional and industrial processes must be determined. The overall objective of these studies was to gain insight on these factors with specific attention on the effect of processing approaches to improve the stability and bioavailability of pro-vitamin A carotenoids from staple and native food. The first study examined the impact of fermentation and thermal processing on the stability and bioaccessibility of pVAC from cassava roots of ten elite biofortified genotypes. Unfermented (UF) and fermented (F) flours were produced from ten genotypes, and bioaccessibility of pVAC was then evaluated from finished products using an in vitro digestion model. Levels of pVAC ranged from 23 to 43 µg of β-CE/g DW, among the studied genotypes. Fermented flours showed higher β-CE retention (p<0.05) during oven-drying and cooking of porridges compared with UF flours. Bioaccessibility of β-CE (ME%) widely ranged (4 to 15%) by showing different effects of fermentation among cassava genotypes. These results are suggestive of an effect of genotype or other factors impacting the release and availability of carotenoids which merit further investigation. The second study addressed the impact of thermal processing in neutral and acid brines on carotenoid stability and bioaccessibility from three different peach palm fruits (yellow, orange and red skin colors). Results showed that ~65% of the carotenoids in peach palm fruits are pVAC, with highest values found in orange and red fruits (Flesh: 162-208 µg β-CE/g DW, Peel: ~850 µg β-CE/g DW. Carotenoids present in flesh and peels of fruits were susceptible to thermal processing (independently from the type of brine) with reductions of β-CE content nearly to the half. However, bioaccessibility of carotenoids (ME%) was affected (p<0.05) by the type of brine. While bioaccessibility of β-CE from peach palm fruits in acid brines was ~20%, compared to ~30% in neutral brines for almost all carotenoids. These results suggest that type of brines used through canning of peach palm may be critical for bioaccessibility of carotenoids. Finally, the third study characterized the major flavonoids in peach palm fruits as C-glucosides flavones derivatives. Around 10 compounds were tentatively identified by using LC-QTOF-MS/MS spectrometry. Total phenolic content in raw fruits ranged from 197 to 275 µg/g DW in raw flesh, while 315 to 395 µg/g DW in raw peels along types of peach palm fruits, with highest content found in red fruits (both flesh and peel) (p<0.05). Although the present study is preliminary, characterization of these promising compounds that may exert a beneficial impact on human health was achieved. However, they may exhibit an opposite behavior by interfering with carotenoids cellular uptake (bioavailability) that may be further evaluated in future studies. All of these results together highlight the susceptibility of carotenoids through common traditional and industrial processes typically applied or encountered by consumers. Interestingly, those conditions not only can decrease levels of carotenoids in food but ultimately interfere with their optimal delivery (bioaccessibility). Our results emphasize the importance of characterization of processing conditions that can promote the stability and bioaccessibility of carotenoids as well as to stablish guidelines for optimal use of this food by consumers, especially those who are at high risk of VAD. Moreover, studying native foods bring the potential to discover new sources of nutritional and bioactive compounds with promising impact in human health.
San Martin-Gonzalez, Purdue University.
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