Development of vinegar obtained from lemon juice: Optimization and chemical characterization of the process

Enhancing citric acid tolerance of Acetobacter tropicalis using chemical and physical mutagenesis and adaptive evolution to improve the quality of lemon fruit vinegar

The high concentration of citric acid in lemons limits the production of lemon fruit vinegar because it inhibits the metabolism of acetic acid bacteria and reduces the utilization of raw materials. This study aimed to enhance the citric acid tolerance of Acetobacter tropicalis by using complex mutagenesis and adaptive laboratory evolution (ALE) and improving the quality of lemon fruit vinegar. After mutagenesis and ALE, A. tropicalis JY-135 grew well under 40 g/L citric acid, and it showed high physiological activity and excellent fermentation performance under high concentrations of citric acid. The survival rate and ATP content of JY-135 were 15.27 and 9.30 times higher than that of the original strain J-2736. In the fermentation of lemon fruit vinegar, the acid production and the number of aroma-active compounds were 1.61-fold and 2.17-fold than J-2736. In addition, we found that citric acid tolerance of JY-135 is related to the respiratory electron-transport chain and the tricarboxylic acid (TCA) cycle. This work is of great significance for the production of high-quality lemon fruit vinegar and the enrichment of seed resources of acetic acid bacteria.

Optimized Acetic Acid Production by Mixed Culture of Saccharomyces cerevisiae TISTR 5279 and Gluconobacter oxydans TBRC 4013 for Mangosteen Vinegar Fermentation Using Taguchi Design and Its Physicochemical Properties

This research investigates the enhancement of acetic acid production in the mangosteen vinegar fermentation process through mixed-culture fermentation involving S. cerevisiae TISTR 5279 and G. oxydans TBRC 4013, alongside an analysis of the resulting mangosteen vinegar's qualities and properties using Taguchi Experimental Design (TED). It focuses on key parameters, such as the juice concentration, inoculum ratio, and pasteurization conditions, to optimize acetic acid production. The findings highlight that the unpasteurized condition exerts the most significant influence on acetic acid production yield (p < 0.01), followed by the 3:1 inoculum ratio of S. cerevisiae TISTR 5279 to G. oxydans TBRC 4013 and a 10% mangosteen concentration. The achieved theoretical maximum yield of acetic acid on day 21 was 85.23 ± 0.30%, close to the predicted 85.33% (p > 0.05). Furthermore, the highest recorded acetic acid concentration reached 5.34 ± 0.92%. On day 14 of fermentation, the maximum productivity and yield were 3.81 ± 0.10 g/L/h and 0.54 ± 0.22 g/g, respectively. The resulting mangosteen vinegar exhibited elevated levels of total phenolic content (359.67 ± 47.26 mg GAE/100 mL), total flavonoid content (12.96 ± 0.65 mg CAE/100 mL), and anti-DPPH radical activity (17.67 ± 0.22%), suggesting potential health benefits. Beyond these chemical aspects, the mangosteen vinegar displayed distinct physical and chemical characteristics from the original mangosteen juice, possibly conferring additional health advantages. These findings are promising for industrial vinegar fermentation models and propose the potential use of the product as a valuable dietary supplement.

Influence of Different Bacteria Inocula and Temperature Levels on the Chemical Composition and Antioxidant Activity of Prickly Pear Vinegar Produced by Surface Culture

This work intends to determine the effect on the aroma profile, phenolic content and antioxidant activity of prickly pear vinegars produced by the surface culture at two different fermentation temperatures and using different acetic acid bacteria (AAB) inocula. Prickly pear wine was fermented at two temperature levels (30 and 37 °C) by using bacteria inocula containing Acetobacter,&nbsp;Gluconobacter or a mixture of bacteria isolated from Sherry vinegars. Eighty-five individual volatile compounds from different families and sixteen polyphenolic compounds have been identified. It was confirmed that the highest temperature tested (37 °C) resulted in a lower concentration of volatile compounds, while no significant effect on the vinegars' volatile composition could be associated with the AAB inoculum used. Contrariwise, the highest content of polyphenolic compounds was detected in those vinegars produced at 37 °C and their concentration was also affected by the type of AAB inoculum used. Prickly pear wine displayed greater antioxidant activity than juices or vinegars, while the vinegars obtained through the mixture of AAB from Sherry vinegar showed higher antiradical activity than those obtained through either of the two AAB genera used in this study. It can be therefore concluded that, although the volatile content of vinegars decreased when fermented at a higher temperature, vinegars with a higher content in polyphenols could be obtained by means of partial fermentations at 37 °C, as long as thermotolerant bacteria were employed.

Physicochemical Characteristics of Vinegar from Banana Peels and Commercial Vinegars before and after In Vitro Digestion

Vinegar is a fermented food with a diversity of uses seasoning, salad dressing and flavouring for foods. Since ancient times it is considered a remedy for health and today there are different types of vinegar on the market, and many others are under development. Determination of the physicochemical characteristics of the new types of vinegar is necessary in order to improve them. Therefore, the aim of this paper is to compare the physicochemical characteristics of vinegar obtained from banana peels (with or without boiling peels) at different ages, with those of commercial vinegars. The vinegar from banana peels was obtained and aged in our laboratory, while the commercial vinegars were purchased from a local market. The physicochemical characteristics of all the samples were investigated before and after gastric and intestinal digestion. Inductively coupled plasma mass spectrometry was used to determine the mineral content of the vinegars. Additionally, statistical analysis of the results was performed by applying a one-way analysis of variance. Results showed that vinegar obtained from banana peels is clearer and total dry extract values are lower than those of commercial vinegars. Banana peel vinegars have higher antioxidant activity and total polyphenol content similar to the commercial balsamic vinegars. This study advances the knowledge in the field of vinegar production by using raw agricultural by-products.

Biotechnological Processes in Fruit Vinegar Production

The production of fruit vinegars as a way of making use of fruit by-products is an option widely used by the food industry, since surplus or second quality fruit can be used without compromising the quality of the final product. The acetic nature of vinegars and its subsequent impact on the organoleptic properties of the final product allows almost any type of fruit to be used for its elaboration. A growing number of scientific research studies are being carried out on this matrix, and they are revealing the importance of controlling the processes involved in vinegar elaboration. Thus, in this review, we will deal with the incidence of technological and biotechnological processes on the elaboration of fruit vinegars other than grapes. The preparation and production of the juice for the elaboration of the vinegar by means of different procedures is an essential step for the final quality of the product, among which crushing or pressing are the most employed. The different conditions and processing methods of both alcoholic and acetic fermentation also affect significantly the final characteristics of the vinegar produced. For the alcoholic fermentation, the choice between spontaneous or inoculated procedure, together with the microorganisms present in the process, have special relevance. For the acetic fermentation, the type of acetification system employed (surface or submerged) is one of the most influential factors for the final physicochemical properties of fruit vinegars. Some promising research lines regarding fruit vinegar production are the use of commercial initiators to start the acetic fermentation, the use of thermotolerant bacteria that would allow acetic fermentation to be carried out at higher temperatures, or the use of innovative technologies such as high hydrostatic pressure, ultrasound, microwaves, pulsed electric fields, and so on, to obtain high-quality fruit vinegars.

Application of accelerating energies to the maceration of sherry vinegar with citrus fruits

BACKGROUND

In the present work we propose the use of accelerating energies (microwaves and ultrasounds) to the maceration process of sherry vinegar with citrus fruit peels (orange and lemon). For the application of microwaves, an experimental design has been developed in order to optimize the maceration conditions. To evaluate the effect of these energies on the maceration, the volatile and polyphenolic content of the samples has been analyzed, as well as their sensory characteristics.

RESULTS

Orange peel provided a higher number of volatile and polyphenolic compounds to the vinegar, while lemon's yielded a greater amount of some of them. The multivariate analysis showed that the samples macerated using microwaves were the most similar to the samples macerated in the traditional way. This aspect was corroborated by the sensory analysis, which was more noticeable when orange peel was used in the macerations.

CONCLUSION

Therefore, it seems that the use of microwaves to accelerate maceration is a good alternative to the traditional method of making sherry vinegars macerated with citrus peel, since it cuts down the maceration time from 3 days to just a few minutes. © 2020 Society of Chemical Industry.

Flavored Sherry vinegar with citric notes: Characterization and effect of ultrasound in the maceration of orange peels

Accelerated maceration experiments of orange peels in Sherry vinegar employing ultrasounds (US) have been carried out. Their effect on the vinegaŕs volatile composition as well as on its olfactometric and sensory characteristics have been evaluated. The optimal conditions for the ultrasounds were determined as follows: sonication power 550 W/L; pulses 40 s On and 20 s Off; with orange peel 200 g/L established previously. Statistical studies showed that maceration under ultrasounds increased volatile compounds content, since the vinegars obtained showed a high content in alcohols, aldehydes and terpenes. Regarding the olfactometric study, the control vinegar exhibited the lowest values for the "floral", "greasy" or "citric" categories and the highest value for the "sweet" category, whereas the US macerated vinegars presented the highest and lowest values for the "floral" and the "acid" categories, respectively. Based on their sensory evaluation, the panel members preferred the vinegar where orange peels had macerated under ultrasounds for 90 min. According to the results, ultrasound is a technology that could be employed to broaden the range of products manufactured by Sherry vinegar producers.