foods Article Chemical, Microbiological and Sensory Stability of Steam Extracted Jaboticaba (Myrciaria jaboticaba) Juice Ana Beatriz Neves Martins 1,2 , Mariana Canto 2, Daniel Perrone 2 and Mariana Monteiro 1,* 1 Laboratório de Alimentos Funcionais, Nutrition Institute, Federal University of Rio de Janeiro, Av. Carlos Chagas Filho, 373, CCS, Bloco J, 2◦ Andar, Sala 16, Rio de Janeiro 21941-902, Brazil; [email protected] 2 Laboratório de Bioquímica Nutricional e de Alimentos, Chemistry Institute, Federal University of Rio de Janeiro, Av. Athos da Silveira Ramos 149, CT, Bloco A, Sala 528A, Rio de Janeiro 21941-909, Brazil; [email protected] (M.C.); [email protected] (D.P.) * Correspondence: [email protected]; Tel.: +55-(21)-3938-6449 Abstract: Jaboticaba (Myrciaria jaboticaba) is a Brazilian berry rich in phenolic compounds, much appreciated for its sweet and slightly acid taste, and highly perishable. Thus, we aimed at producing jaboticaba juice by steam extraction and at investigating its microbiological, sensorial and chemical qualities during storage for up to 168 days. Juice was microbiologically safe and even though unsweetened juice was well accepted, sucrose addition further improved flavor (21%), overall impression (11%) and purchase intent (21%) scores. Cyanidin-3-O-glucoside (C3G) was the major phenolic (40%), followed by gallic (28%) and ellagic acids (21%). Total phenolics contents decreased from 27% (50 ◦C) to 50% (25 ◦C), mainly driven by C3G degradation. At 60 ◦C, total phenolics contents did not change after 42 days since C3G degradation was counterbalanced by gallic acid formation (129%), which followed zero-order reaction kinetics. Anthocyanins degradation followed first-order reaction kinetics (C3G half-life at 25 ◦C = 21.7 days) and was associated with color changes Citation: Martins, A.B.N.; Canto, M.; during storage. In conclusion, steam extraction followed by hot-filling technique ensured a juice with Perrone, D.; Monteiro, M. Chemical, at least six months of shelf life. Microbiological and Sensory Stability of Steam Extracted Jaboticaba Keywords: anthocyanins; ellagic acid; gallic acid; Jaboticaba; kinetic models; shelf life; sensory (Myrciaria jaboticaba) Juice. Foods 2021, analysis 10, 732. https://doi.org/ 10.3390/foods10040732 Academic Editor: Paola Montoro 1. Introduction Jaboticaba (or jabuticaba) is a spherical, purple to black colored fruit native to Brazil. Received: 10 March 2021 It belongs to the Myrtaceae family and Plinia genus, also referred as Myrciaria [1], especially Accepted: 26 March 2021 Published: 30 March 2021 in the scientific field. Its pulp is whitish, juicy and gelatinous, with sweet and slightly acid taste. Beyond its sensory characteristics, the fruit not only shows a valuable nutritional Publisher’s Note: MDPI stays neutral profile—dietary source of carbohydrates, fibers, vitamins and minerals—but also high with regard to jurisdictional claims in phenolics content, mainly anthocyanins and ellagitannins. However, as a result of its high published maps and institutional affil- perishability, jaboticaba consumption and commercialization are limited to the areas of iations. cultivation and their surroundings [2]. In this sense, the development of jaboticaba-based products is an alternative to prevent post-harvest losses and also a way to add value to the fruit. There is a growing research interest related to the development of jaboticaba-based products, such as juices [3,4], alco- holic beverages [5–7], and vinegar [8]. In fact, some products containing jaboticaba, such Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. as yogurts, ice pops, jams, beverages and chocolate have already reached the market, but This article is an open access article their availability is still low. Among these products, juices show high commercial potential, distributed under the terms and as this is an expanding market, and novel fruit drinks, of exotic flavors and with functional conditions of the Creative Commons properties, are becoming increasingly popular. Moreover, due to consumers concerns Attribution (CC BY) license (https:// related to food quality, the food industry has been focusing on product development based creativecommons.org/licenses/by/ on healthier ingredients and innovative processing technologies [9]. 4.0/). Foods 2021, 10, 732. https://doi.org/10.3390/foods10040732 https://www.mdpi.com/journal/foods Foods 2021, 10, 732 2 of 13 Mechanical extraction methods, such as pressing, squeezing and depulping, are commonly used by the food industry to produce fruit juice, requiring post-production processing to avoid microbial spoilage and chemical changes. As an alternative, steam extraction is a method based on raising water vapor, which reaches the fruit, transferring heat and leaching out the pulp. It is reported to inactivate enzymes and pasteurize juice during its extraction, thus not requiring the application of any further preservation tech- nology [10]. Since it is considered a rapid and low-cost method, small- and medium-scale industries conventionally use steam extraction to produce red grape juice, although juices produced by this technology are slightly diluted due to the transfer of exogenous water during the process [11]. Maintaining juice quality throughout food chain is a relevant issue as quality losses are expected over time. In berries juices, the major challenge is dealing with changes in phenolic compounds, especially anthocyanins, due to their instability towards external factors, such as light, oxygen, temperature [12]. Therefore, the objectives of the present study were to produce jaboticaba juice by steam extraction and to investigate its quality during storage, with emphasis on the changes of its phenolics profile. 2. Materials and Methods 2.1. Standards and Chemicals Sugars, organic acids and non-anthocyanins phenolic compounds standards were pur- chased from Sigma-Aldrich Chemical Co. (St. Louis, MO, USA). Anthocyanins standards were purchased from Indofine Chemical Co. (Hillsborough, NJ, USA). Solvents and water (Milli-Q system, Millipore, Bedford, MA, USA) were HPLC grade. 2.2. Jaboticaba Juice Processing and Storage Jaboticaba fruits (Myrciaria jaboticaba, cv. Sabará) from Minas Gerais, Brazil, were purchased at Rio de Janeiro’s agricultural trading center and frozen until use. Unsweet- ened and sweetened jaboticaba juices (UJJ and SJJ, respectively) were produced by steam extraction using a laboratory-scale stainless-steel steam juicer (Cook N Home, City of Industry, CA) (Figure S1). Thawed and crushed fruits (4 kg) were added after water (3 L) began to boil and extraction was performed for 30 min, yielding approximately 2.2 L of juice. Sucrose (134 g) was added together with the fruits. Juices were produced in triplicate, bottled while hot (~80 ◦C) in dark glass bottles and stored at 25, 40, 50 and 60 ◦C in a temperature-controlled oven for up to 168 days to evaluate the impact of long-term storage on juice chemical composition and microbiological and sensory qualities. The extraction time was chosen after preliminary tests with different extraction times (up to 60 min), taking into account juice yield, anthocyanin content and residual bitter taste. Extraction times superior to 30 min led to less expressive increases in both yield and anthocyanin content while resulted in more noticeable aftertaste. The amount of added sucrose (6% w/v) was based on previous literature data [3]. SJJ was produced to evaluate the impact of sucrose addition on jaboticaba juice processing and on its phenolic compounds stability during storage. 2.3. Sugar Analysis by HPLC-ELSD Sugar contents were determined for UJJ stored at 25 ◦C for up to 112 days, with 56-days intervals. Juices were diluted with acetonitrile and centrifuged (11,300 rpm, 10 min). The supernatant was collected and filtered through a 0.45 µm cellulose ester membrane (Millipore, Barueri, Brazil). The liquid chromatography system (Shimadzu, Kyoto, Japan) included a LC-20AT quaternary pump, a 8125 manual injector (Rheodyne) with a 20 µL loop, an ELSD-LT II evaporative light scattering detector, a CBM-20A system controller and a DGU-20A5 de- gasser. Chromatographic separation was performed according to Ma et al. [13], with slight modifications. A normal phase column (NH2, 5 µm, 250 mm × 4.6 mm, Zorbax) was used and the mobile phase (isocratic elution) consisted of a mixture of acetonitrile/water (85:15, Foods 2021, 10, 732 3 of 13 v/v), with a flow rate of 1.0 mL/min. ELSD was set to gain 4, 40 ◦C and 350 kPa nebulizer gas pressure (N2). Identification was performed by comparison with retention time of the respective standard and quantification by external standardization. Limits of detection (LOD) and quantification (LOQ) for sugars were equal to or lower than 0.047 g/100 mL and 1.142 g/100 mL. Data were acquired by LC solution software (Shimadzu Corporation, version 1.25). 2.4. Organic Acids Analysis by HPLC-DAD Organic acids contents were determined for UJJ stored at 25 ◦C for up to 112 days, with 56-days intervals. Juices were centrifuged and filtered as previously described. The liquid chromatography system (Shimadzu) included two parallel pumps LC- 20AD, automatic injector SIL-20AHT, diode array detector (DAD) SPD-M20A, system controller CBM-20A and degasser DGU-20A5. Chromatographic separation was performed according to Scherer et al. [14], with slight modifications. A reverse phase column (C18, 5 µm, 150 mm × 4.6 mm, Phenomenex) was used and the mobile phase (isocratic elution)