ORIGINAL ARTICLE Effect of ultrasound on microbiological load and antioxidant properties of blackberry juice Esther Ramírez-Moreno 1 | Quinatzin Yadira Zafra-Rojas 1 | Jos  e Arias-Rico 2 | Jos  e Alberto Ariza-Ortega 1 | Ernesto Alanís-García 1 | Nelly Cruz-Cansino 1 1  Area Acad emica de Nutrici on, Instituto de Ciencias de la Salud, Universidad Aut onoma del Estado de Hidalgo, San Agustín Tlaxiaca, C.P. 42160 Pachuca, Hidalgo, M exico 2  Area Acad emica de Enfermería, Instituto de Ciencias de la Salud, Universidad Aut onoma del Estado de Hidalgo, San Agustín Tlaxiaca, C.P. 42160 Pachuca, Hidalgo, M exico Correspondence Nelly Cruz-Cansino, Universidad Aut onoma del Estado de Hidalgo, Carr. Actopan- Tilcuautla s/n, Ex hacienda la concepci  on, San Agustín Tlaxiaca, C.P. 42160 Pachuca, Hidalgo, M exico. Email: ncruz@uaeh.edu.mx Funding information Secretaria de Educaci  on P ublica (SEP), Grant/Award Number: PRODEP-37/ Rev-04; Universidad Aut onoma del Estado de Hidalgo of M exico, Grant/Award Number UAEH-EXB-078 Abstract The objective of this study was to evaluate the effect of ultrasound (60 and 80% amplitude, 15 and 25 min) of blackberry juice on physicochemical (pH and total soluble solids), microbiological analysis (total plate count and Enterobacteria), and in vitro intestinal bioaccessibility of polyphenols and antioxidant activity (ABTS, DPPH). Ultrasound treatment caused a decrease of microbial count of blackberry juice and remained its physicochemical properties without change. The blackberry juice had a high antioxidant activity, however, after of the in vitro digestion process only 28% of total polyphenols were considered as intestinally bioaccessible, with the contribution of 30 to 60% of antioxidant activity in the bioaccesible fraction. The treatment at 80% amplitude for 15 min was the better treatment due it had an increase of bioaccessibility of polyphenols and antioxidant activity measured by ABTS. Our results showed that ultrasound treatment can preserve the black- berry juice without impairing to its antioxidant characteristics. Practical applications Blackberries are mostly consumed fresh but are also commercialized as individually quick frozen packs, bulk, frozen, seedless or seeded puree, freeze-dried, juice, or concentrate. During fruit juices processing, thermal treatment and other conditions such as oxidation, light exposure, sugar addi- tion, changes in pH, and temperature readily reduce the content of antioxidant compounds and its nutritional properties. Ultrasound is a non-thermal processing technology with potential to replace the traditional thermal pasteurization, achieve microbial safety in fruit juices and remained its anti- oxidant properties of the blackberry juice. 1 | INTRODUCTION Blackberries are an important crop in the United States and M exico, where they are commercially produced over wide geographic range (Reyes-Carmona, Yousef, Martínez-Peniche, & Lila, 2005). It is a highly valued fruit due to its high content of anthocyanins and ellagitannins, and other phenolic compounds of high antioxidant capacity (Cho, Howard, Prior, & Clark, 2004). Blackberries are mostly consumed fresh but are also commercialized as individually quick frozen packs, bulk frozen, seedless or seeded puree, freeze-dried, juice or concentrate. During fruit juices processing, thermal treatment and other conditions such as oxidation, light exposure, sugar addition, changes in pH, and temperature readily reduce the content of antioxidant compounds and its nutritional properties (Sadilova, Stintzing, Kammerer, & Carle, 2009). Alternative processing methods that preserve nutritional charac- teristics and extend shelf life may prevent this loss. Several emerging technologies have been used for blackberries processing such as high- pressure, pulsed electric fields, ozonation, UV-B irradiance, ultrasound, and others (Barba et al., 2012; Basiouny, 1998; Patras, Brunton, Da Pieve, & Butler, 2009). Ultrasound is a non-thermal processing technol- ogy with potential to replace the traditional thermal pasteurization and achieve microbial safety in fruit juices (Cheng, Soh, Liew, & Teh, 2007; Raviyan, Zhang, & Feng, 2005; Valero et al., 2007; Zafra-Rojas et al., 2013). When the high-power ultrasound propagates in a liquid, cavitation bubbles are generated due to pressure changes. These micro-bubbles collapse violently in the succeeding compression cycles Abbreviations: ABTS, 2,2 0 azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) diammonium salt; DPPH, 1,1-diphenyl-2-picrylhydrazyl; TC, total plate count; TPC, total phenolic content; TSS, total soluble solids. J Food Process Preserv. 2018;42:e13489. https://doi.org/10.1111/jfpp.13489 wileyonlinelibrary.com/journal/jfpp V C 2017 Wiley Periodicals, Inc. | 1 of 6 Received: 14 December 2016 | Revised: 14 March 2017 | Accepted: 17 August 2017 DOI: 10.1111/jfpp.13489