The aim of this study was to determine the impact of three different technological processes and in vitro digestion on the profile and content of betalains and inhibition of angiotensin I converting enzyme (ACE) in red beet. Betalains were analysed by the micro-HPLC-TOF-MS/MS method, while ACE inhibition was determined by an in vitro assay. In the tested samples, thirteen betalains were identified, constituting nine betacyanins, two betaxanthins and two betalain precursors. The applied technological processes (boiling, fermentation and microwave-vacuuming treatment) reduced the content of betalain by 42–70% in the obtained products. The contribution of betalains released from red beet products after in vitro digestion was detected within the range of 0.001–0.10%. The applied treatments reduced the inhibition of ACE by the non-digested red beet products, while in vitro digestion caused an increase in ACE inhibition in the case of the digested solid red beet products.