Effect of In Vitro Gastrointestinal Digestion on Amino Acids, Polyphenols and Antioxidant Capacity of Tamarillo Yoghurts.

Tung Thanh Diep,Michelle Ji Yeon Yoo,Elaine Rush

doi:10.3390/ijms23052526

Abstract

Laird’s Large tamarillo powder is high in protein (10%) essential amino acids (EAAs), gamma-aminobutyric acid (GABA) and polyphenols (0.6% phenolics plus anthocyanins) and fibre 25%. This study aimed to investigate, using a standardized static in vitro digestion model, the stability of amino acids and antioxidant capacity of polyphenols in yoghurt fortified with 5, 10 and 15% tamarillo powder either before (PRE) or after (POS) fermentation. Compared to plain yoghurt, the fruit polyphenols (rutinosides and glycosides) were retained and substantial increases in FEAAs (free essential amino acids), total phenolic content (TPC) and antioxidant activity were observed particularly at the end of intestinal phase of digestion. Together with SDS-PAGE results, peptides and proteins in tamarillo yoghurts were more easily digested and therefore may be better absorbed in the small intestine compared to the control. TPC and antioxidant activity of fortified yoghurts increased significantly after in vitro digestion. Relatively high bioaccessibilty of chlorogenic acid and kaempferol-3-rutinoside in digested PRE samples was observed. The results suggest that the yoghurt matrix might protect some compounds from degradation, increasing bioaccessibility and in the small intestine allow increased absorption and utilization possible. Fortification would deliver intact polyphenols and fibre to the large intestine and improve gut health. Further research of acceptability, shelf life, and then trials for health effects should be implemented.

Highlights

The development of new food products with a potentially positive effect on health using traditional fruits, is generally desirable since there is an increasing interest among consumers to look for safe, healthy, sustainable and natural foods [1]
The intensity of β-lactoglobulin, the predominant component of whey protein, was similar for all yoghurt samples indicating that this compound was not degraded with or without addition of tamarillo powder
Α-lactalbumin showed higher intensity for control and the tamarillo yoghurts produced from the post-fermentation process rather than yoghurts fortified in pre-fermentation

Summary

Introduction

The development of new food products with a potentially positive effect on health using traditional fruits, is generally desirable since there is an increasing interest among consumers to look for safe, healthy, sustainable and natural foods [1]. Tamarillo powder has a high fibre content (25%), essential for bowel health. Tamarillo fruit contains a spectrum of polyphenol components including the blue-red coloured anthocyanins; delphinidin-3rutinoside (254.76 mg/100 g DW) and pelargonidin-3-rutinoside (200.66 mg/100 g DW), and the colourless phenolics, chlorogenic acid (66.35 mg/100 g DW) and kaempferol-3-rutinoside (50.04 mg/100 g DW) contributing to high antioxidant activity (52.42 and 60.19 μmol TEAC/g DW determined by CUPRAC and FRAP assays, respectively) [4]. It has been reported that tamarillo polyphenols have shown promising effects including antioxidation and antioxidative stress [5], anti-obesity [6], anticancer [7,8], antimicrobial activity [9] as well as protection against lipid oxidation [10]

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Conclusion