Contents lists available at ScienceDirect LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt Healthy dried baby corn silk vinegar production and determination of its main organic volatiles containing antimicrobial activity Warawut Krusong a,* , Wiramsri Sriphochanart a , Rachit Suwapanich a , Orachorn Mekkerdchoo a , Pongsert Sriprom a , Angkana Wipatanawin b , Salvatore Massa a,c,1 a Faculty of Agro-Industry, King Mongkut's Institute of Technology Ladkrabang, Ladkrabang, Bangkok, 10520, Thailand b Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand c Department of Agricultural, Food and Environmental Sciences, Foggia University, Foggia, Italy ARTICLE INFO Keywords: Dried baby corn silks Active compounds Acetification Antimicrobial volatiles ABSTRACT Dried baby corn silks (DBCS) are an underutilized by-product and a good source of active compounds. Analysis of DBCS showed 5.15 ± 0.21 mg GAE mL -1 total phenolic compounds, 4.24 ± 0.08 mg GAE mL -1 total fla- vonoid compounds and an antioxidant activity of 45.98 ± 7.89% inhibition for free radical scavenging DPPH, 91.33 ± 0.33% inhibition for ABTS and 44.17 ± 0.53% chelating effect for FIC. In the acetification process, 15 g L -1 (w/v) DBCS was suitable for wine making resulting in 94 ± 1 g L -1 alcohol. Subsequently, acetic acid (62 ± 1 to 75 ± 1gL -1 ) was produced during 9 cycles of semi-continuous processing. The remaining active compounds, in both wine and vinegar, were also determined and a significant reduction (p ≤ 0.5) of total phenolic compounds and antioxidant activity from DBSC was observed, which were higher in vinegar than in wine. Among volatile organic compounds found using GC-MS, only five of the main compounds, which had antimicrobial properties, were found in both wine and vinegar. They were acetic acid, ethyl ester; 1-butanol, 3- methyl-, acetone; 1-butanol, 3-methyl-; hexanoic acid and octanoic acid. Results indicated that DBCS contained compounds that were beneficial to health and therefore could be a functional food and provide additional beneficial applications as an antimicrobial agent. 1. Introduction Baby corn is the unfertilized young ear of the sweetcorn plant (Zea mays L.). The ears are harvested from the plant when they are a few days old and the cobs, which are used as a vegetable, are removed and the sheath and silks, which make up 85% of the ear, are discarded or used as animal feed. It has previously been shown that baby corn silks (BCS) are a rich source of bioactive compounds including volatile oils, steroids (stigmasterol and sitosterol), saponins and natural antioxidants (phenolic compounds and flavonoids) (Gwendlin, Induja, Manoj, & Shivasamy, 2015; Hasanudin, Hashim, & Mustafa, 2012; Ng & Wan Rosli, 2013) as well as proteins, carbohydrates, vitamins, alkaloids, tannins and mineral salts (Kwag, Lee, Jang, & Kim., 1999). BCS have also been traditionally used as a therapeutic remedy for inflammation of the urinary bladder and prostate and treatment for irritation of the urinary system (El-Ghorab, El-Massry, & Shibamoto, 2007). The value of exploring the conversion of corn silks into value-added products, especially healthy vinegar, is interesting. It is necessary to keep the silks in a dry form before use to protect them from microbial contamination. Three acetification processes which are continuous surface fer- mentation, generator process with a fixed-bed reactor, and submerged fermentation with high rate of acetification have been generally used worldwide (Lotong, Malaphan, Boongorsrang, & Yongmanitchai, 1989). Currently the industrialized vinegar production by acetic acid bacteria (AAB) is a submerged semi-continuous process (de Ory, Romero, & Cantero, 2004; Fregapane, Rubio-Fernandez, & Salvador, 2003). After starting the process, a given volume of bioreactor is discharged (acetic acid as finished product) at the end of every cycle, and recharged with initial medium (fresh wine with nutrients) at the same volume. Con- sequently we focused on this semi-continuous process to develop a healthy vinegar product from dried baby corn silks (DBCS). Previously DBCS has been shown that there are antimicrobial or- ganic volatiles in corn silks (Hasanudin et al., 2012; Zeringue, 2000) that contain broad-spectrum killing properties against, not only mi- croorganism, but also plant and human pathogens (Strobel, Dirksie, Sears, & Markworth, 2001). However, there are no reports concerning https://doi.org/10.1016/j.lwt.2019.108620 Received 30 January 2019; Received in revised form 9 September 2019; Accepted 10 September 2019 * Corresponding author. E-mail address: warawut.kr@kmitl.ac.th (W. Krusong). 1 Visiting Professor at KMITL. LWT - Food Science and Technology 117 (2020) 108620 Available online 13 September 2019 0023-6438/ © 2019 Elsevier Ltd. All rights reserved. T