Linking the Dynamic Changes in the In Vitro Antioxidant Activity of Carob Kibbles upon Roasting to the Chemical and Structural Changes Revealed by FTIR Spectroscopy

Abstract

Recent studies have highlighted the potential of utilizing carob kibbles as a bioactive-rich food ingredient associated with substantial health benefits. Roasting is a key process in enhancing the sensory characteristics of carob kibbles, also affecting the bioactive polyphenols and leading to the formation of Maillard reaction products (MRPs), including the polymeric melanoidins that are associated with a high antioxidant potential but remain unexplored in carob. In this work, we employed for the first time attenuated total reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy to probe the dynamic chemical and structural changes upon the roasting of carob kibbles, along with the investigation of the in vitro antioxidant activity through the 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and the determination of the total polyphenolic, proanthocyanidin, gallic acid and cinnamic acid contents. Roasting significantly enhanced the in vitro antioxidant activity of the polyphenolic carob extracts, with different rates at distinct roasting temperatures. The ATR-FTIR analysis enabled the identification of the changes in the structural features of polyphenolic compounds that were related to the improved antioxidant activity upon roasting. Furthermore, the detection of characteristic signatures for the polymeric melanoidins in the infrared (IR) fingerprint region provided the first evidence for the formation and structural properties of these complex, diverse compounds in roasted carob kibbles.

Evaluation of the Biological Potential of Himanthalia elongata (L.) S.F.Gray and Eisenia bicyclis (Kjellman) Setchell Subcritical Water Extracts

“…Comparing the Maillard reaction products and the TPC content of seaweeds, it can be observed that, particularly for E. bicyclis , there is an increase in the TPC content in fraction 3 that can be positively related to AGEs present in this fraction ( Table 2 ) [ 43 ]. According to Plaza et al [ 43 ] and Grigoriou and Pinakoulaki [ 53 ], besides phenolics, there are other classes of compounds that positively react with Folin–Ciocalteu reagent due to the presence of reducing groups. One example is the Maillard reaction products.…”

Formation, Evolution, and Antioxidant Activity of Melanoidins in Black Garlic under Different Storage Conditions

“…FT-IR analysis was conducted with an FT-IR attenuated total reflection (ATR) spectrometer (Thermo Scientific, Waltham, MA, USA). Spectra records were kept at a resolution between 400 and 4000 cm −1 for 64 scans [21].…”

Bioavailability and Bioactivity of Plant Antioxidants

“…Thermal processes can cause changes in the chemical composition, structure of compounds, and the bioactive properties of food. For example, roasting affects the qualitative and quantitative composition of polyphenols, the formation of Maillard reaction products and, consequently, the antioxidant potential of carob kibbles [ 6 ]. Thermal treatment also causes the degradation of anthocyanins, flavonoids, and other polyphenols and reduces the antioxidant activity of the red grape skin extract to a degree depending on the process parameters used (time, temperature) [ 7 ].…”