The potential meat flavoring derived from Maillard reaction products of rice protein isolate hydrolysate-xylose via the regulation of temperature and cysteine

Abstract

Maillard reaction products (MRPs) derived from rice protein isolate hydrolysate and D-xylose, with or without L-cysteine, were developed as a potential meat flavoring. The combined impact of temperature (80-140 °C) and cysteine on fundamental physicochemical characteristics, antioxidant activity, and flavor of MRPs were investigated through assessments of pH, color, UV-visible spectra, fluorescence spectra, free amino acids, volatile compounds, E-nose, E-tongue, and sensory evaluation. Results suggested that increasing temperature would reduce pH, deepen color, promote volatile compounds formation, and reduce the overall umami and bitterness. Cysteine addition contributed to the color inhibition, enhancement of DPPH radical-scavenging activity and reducing power, improvement in mouthfulness and continuity, reduction of bitterness, and the formation of sulfur compounds responsible for meaty flavor. Overall, MRPs prepared at 120 °C with cysteine addition could be utilized as a potential meat flavoring with the highest antioxidant activity and relatively high mouthfulness, continuity, umami, meaty aroma, and relatively low bitterness.

Keywords: Antioxidant activity; Cysteine; Maillard reaction; Meaty flavor; Rice protein isolate hydrolysate; Temperature.

Graphical abstract

Fig. 1

Effects of temperature and cysteine on the fundamental physicochemical properties of Maillard reaction products derived from rice protein isolate hydrolysate and xylose: (a) pH, (b) color, (c) ultraviolet absorption spectra, and (d) fluorescence spectra. Values followed by different lowercase letters mean statistically significant (p < 0.05) differences among different products. RHX-MRPs mean rice protein isolate hydrolysate-xylose Maillard reaction products, and RHX-80, RHX-100, RHX-120, and RHX-140 represent RHX-MRPs prepared at different temperatures of 80, 100, 120, and 140 °C, respectively. RHXC-MRPs mean rice protein isolate hydrolysate-xylose-cysteine Maillard reaction products, and RHXC-80, RHXC-100, RHXC-120, and RHXC-140 represent RHXC-MRPs prepared at different temperatures of 80, 100, 120, and 140 °C, respectively.

Fig. 2

Effects of temperature and cysteine on the antioxidant activity of Maillard reaction products derived from rice protein isolate hydrolysate and xylose: (a) DPPH radical scavenging activity and (b) reducing power at 700 nm. Values followed by different lowercase letters mean statistically significant (p < 0.05) differences among different products. RHX-MRPs mean rice protein isolate hydrolysate-xylose Maillard reaction products, and RHXC-MRPs mean rice protein isolate hydrolysate-xylose-cysteine Maillard reaction products.

Fig. 3

Flavor wheel of RHX-MRPs and RHXC-MRPs based on volatile compounds. RHX-MRPs mean rice protein isolate hydrolysate-xylose Maillard reaction products, and RHX-80, RHX-100, RHX-120, and RHX-140 represent RHX-MRPs prepared at different temperatures of 80, 100, 120, and 140 °C, respectively. RHXC-MRPs mean rice protein isolate hydrolysate-xylose-cysteine Maillard reaction products, and RHXC-80, RHXC-100, RHXC-120, and RHXC-140 represent RHXC-MRPs prepared at different temperatures of 80, 100, 120, and 140 °C, respectively.

Fig. 4

Heat map of volatile compounds formed in RHX-MRPs and RHXC-MRPs: (a) overview of all kinds of volatile compounds, (b) aliphatic oxygen-containing compounds, (c) non sulfur-containing furan compounds, (d) nitrogenous heterocyclic compounds, and (e) sulfur-containing compounds. The change in color from blue to red in the heat map represents a gradual increase in the relative content of volatile compounds. RHX-MRPs mean rice protein isolate hydrolysate-xylose Maillard reaction products, and RHX-80, RHX-100, RHX-120, and RHX-140 represent RHX-MRPs prepared at different temperatures of 80, 100, 120, and 140 °C, respectively. RHXC-MRPs mean rice protein isolate hydrolysate-xylose-cysteine Maillard reaction products, and RHXC-80, RHXC-100, RHXC-120, and RHXC-140 represent RHXC-MRPs prepared at different temperatures of 80, 100, 120, and 140 °C, respectively. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Fig. 5

The odor and taste attributes of RHX-MRPs and RHXC-MRPs analyzed using instrumental sensory analysis system: (a) radar diagram, (c) score plot and (d) loading plot of PCA for E-nose; (b) radar diagram, (e) score plot and (f) loading plot of PCA for E-tongue. There are 10 sensor probes in an E-nose system consisted of W1C (sensitive to aromatic compounds, benzene), W5S (highly sensitive to nitrogen oxides), W3C (sensitive to aromatic compounds, ammonia), W6S (sensitive to hydrogen), W5C (sensitive to olefin, short-chain aromatic compounds), W1S (sensitive to methyl), W1W (sensitive to sulfur compounds), W2S (sensitive to alcohols, aldehydes, and ketones), W2W (sensitive to organic sulfides), and W3S (sensitive to long-chain alkanes). RHX-MRPs mean rice protein isolate hydrolysate-xylose Maillard reaction products, and RHX-80, RHX-100, RHX-120, and RHX-140 represent RHX-MRPs prepared at different temperatures of 80, 100, 120, and 140 °C, respectively. RHXC-MRPs mean rice protein isolate hydrolysate-xylose-cysteine Maillard reaction products, and RHXC-80, RHXC-100, RHXC-120, and RHXC-140 represent RHXC-MRPs prepared at different temperatures of 80, 100, 120, and 140 °C, respectively. The clean air is used as the blank sample for E-nose analysis and umami solution consisting of 0.5% (w/v) sodium chloride (NaCl) and 1.0% (w/v) monosodium glutamate (MSG) is used as the blank sample for E- tongue analysis.

Fig. 6

The correlation analysis among free amino acids, volatile compounds, antioxidant activity, instrumental sensory data (E-nose and E-tongue), and descriptive sensory evaluation through PCA and PLSR analysis: (a) and (b) PCA correlation loading plot between volatile compounds and antioxidant activity for RHX-MRPs, (c) and (d) PCA correlation loading plot between volatile compounds and antioxidant activity for RHXC-MRPs, (e) PLSA correlation loading plot between volatile compounds, E-nose, and descriptive sensory evaluation, and (f) PLSA correlation loading plot between free amino acids, E-tongue, and descriptive sensory evaluation. For Fig. 6(e), the X-matrix is designed using GC–MS data, while the Y-matrix is designed using E–nose (W5S, W1S, W2S, W1W, and W2W) and descriptive sensory attributes (burnt, caramel, and meaty), respectively. For Fig. 6(f), the X-matrix is designed using FAA content, while the Y-matrix is designed using E–tongue (bitterness, umami, saltiness, and richness) and descriptive sensory attributes (mouthfulness, continuity, umami, bitterness, and salty), respectively. E-T means taste sensors of E–tongue.