Impact of sweet potato peels extracts obtained by pulsed electric fields on the growth of probiotic strains from Lactobacillus genus

Abstract

This work describes the first approach for the valorization of sweet potato (Sp) peels assisted by pulsed electric fields (PEF) to obtain extracts that enhance the growth of potential probiotic bacteria. Four different varieties were studied, namely white sweet potato (WSp, “O'Henry”), white with purple (WPSp or “Violeta Roja”), orange (OSp or “California”) and purple (PSp, “Pepita”). Among them, the PEF extracts obtained from PSp had a noticeable content of carbohydrates, polyphenols and flavonoids (12.5 mg/mL, 4.34 mg GAE/g and 1.73 mg GAE/g, respectively), being in any case higher than those obtained by maceration extraction. The analysis by quantitative Nuclear Magnetic Resonance (qNMR) allowed us to identify sucrose, fructose and glucose as the main sugars extracted, with a total concentration close to 94 mg/g PSp for the PSp-PEF crude extracts, which entails an enhancement by up to 92% with respect to the conventional extraction. Furthermore, these extracts improved the growth kinetics of probiotic bacteria, Lactobacillus members and also, the production of short chain fatty acids (SCFA). This fact should be also noted since they are considered valuable platform chemicals to be transformed into high-added-value, thus proposing another way for valorization. Industrial relevanceThe relevance of this work lies in the necessity of searching new sustainable foods for their consumption, and the processing of these foods by means of innovative technologies. In light with this fact, the suitability of PEF-assisted extraction to be scaled-up at industrial level would pave the way for an efficient, notable conversion of wasted sweet potato (Sp) peels to potential prebiotics, boosting the recovery of these compounds by PEF technology with respect to traditional extraction methods and the health benefits.