Actinidin Enhances Gastric Protein Digestion As Assessed Using an in Vitro Gastric Digestion Model

• Published in: Journal of agricultural and food chemistry Vol. 58; no. 8; pp. 5068 - 5073
• Main Authors: Kaur, Lovedeep, Rutherfurd, Shane M, Moughan, Paul J, Drummond, Lynley, Boland, Mike J
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 28.04.2010
• Subjects: Actinidia deliciosa; actinidin; Biological and medical sciences; Chromatography, High Pressure Liquid; Cysteine Endopeptidases - pharmacology; cysteine proteinases; dietary protein; Digestion; Electrophoresis, Polyacrylamide Gel; enzyme activity; Food Chemistry/Biochemistry; Food industries; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; gastric digestion; Hydrogen-Ion Concentration; in vitro digestion; In Vitro Techniques; Intestine, Small - metabolism; kiwifruit; pepsin; proteins; Proteins - metabolism; stomach; Kiwifruit; in vitro protein digestion; SDS−polyacrylamide gel electrophoresis; Actinidia deliciosa; actinidin; Fruit; Gel electrophoresis; Digestion; Actinidiaceae; In vitro; Protein; SDS―polyacrylamide gel electrophoresis; Kiwi (fruit); Dicotyledones; Angiospermae; Spermatophyta; Models
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf903332a

Consumption of kiwifruit has long been claimed anecdotally to assist in gastric digestion. This has generally been assumed to be due to the presence of the proteolytic enzyme actinidin; however, there is little published evidence supporting this assumption. This paper reports the findings of an in vitro study that examined the effect of kiwifruit proteases (actinidin) on the digestion of a range of common food proteins under simulated gastric conditions. An extract from green kiwifruit containing actinidin was prepared. Several protein sources derived from soy, meat, milk, and cereals were incubated in the presence or absence of the kiwifruit extract using an in vitro digestion system consisting of incubation with pepsin at pH 1.9, simulating gastric digestion in humans. The digests were subjected to gel electrophoresis (SDS-PAGE). For some protein sources, simulated digestion in the presence of kiwifruit extract resulted in a substantially greater loss of intact protein and different peptide patterns from those seen after digestion with pepsin alone. As an example, the addition of actinidin extract enhanced the digestion of α-, β-, and κ-caseins in sodium caseinate by 37, 33, and 48%, respectively. Under simulated gastric conditions, kiwifruit extract containing actinidin enhanced the digestion of some, but not all, food proteins over and above that found with pepsin alone.