Fruit juice offers a fresh take on kombucha
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Researchers brewed kombucha (left) and kombucha-like beverages from passion fruit (center) and apple (right) juices and found that the apple-based drink had the most flavonoids and ranked most favorable among a panel of taste testers.
view moreCredit: Adapted from ACS Agricultural Science & Technology 2024, DOI:10.1021/acsagscitech.4c00372
Kombucha is a fizzy, tangy drink made by fermenting tea. But brewers are now fermenting other plant-based drinks to explore nutritional properties and flavors. Researchers in ACS Agricultural Science & Technology compared the biochemistry and flavor of kombucha with brews made from apple and passion fruit juices. They found that the apple beverage contained high levels of bioactive compounds called flavonoids and ranked highly among taste testers, signaling its promise as a kombucha alternative.
To make kombucha, brewers ferment sweetened tea with a spongy disk of microbes known as a SCOBY, or symbiotic culture of bacteria and yeast. The resulting beverage contains beneficial bacteria from the fermentation process and bioactive compounds from the tea, including flavonoids, phenolics and anthocyanins that may have antioxidant and anti-inflammatory properties. Few studies have investigated whether liquids other than tea could be brewed as kombucha-like beverages with boosted antioxidant levels or unique flavors. So, Socorro Vanesca, Frota Gaban and coworkers fermented antioxidant-rich apple and passion fruit juices with a SCOBY to find out.
After fermenting apple juice, passion fruit juice, and tea in separate jars for 10 days at room temperature, the researchers measured the levels of several bioactive compounds in each brew and found that:
- The apple beverage had the highest level of flavonoids, followed by kombucha and the passion fruit drink.
- The kombucha and apple beverages had comparable levels of phenolic compounds that were higher than those of the passion fruit beverage.
- All three brews had similar amounts of anthocyanin, a red-colored antioxidant.
The researchers asked 12 volunteer taste testers to evaluate each beverage’s color, aroma and flavor. The taste testers noted an amber color for the apple beverage, yellow for passion fruit and gold for the kombucha. The volunteers reported stronger, fruitier aromas for the fermented fruit juices compared with the tea. However, the passion fruit drink tasted more bitter than the sweeter apple and tea drinks, both of which received equal votes as the favorite beverage. Because fermented apple juice has more flavonoids and a pleasant taste compared with the other beverages, the researchers say it could be a successful alternative to kombucha made from tea. They plan to explore health benefits and flavors of other fermented fruits in the future.
The authors acknowledge funding from the Coordination for the Improvement of Higher Education Personnel.
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Journal
ACS Agricultural Science & Technology
Article Title
“Physicochemical Properties, Antioxidant Activity, and Sensory Profiles of Kombucha and Kombucha-Like Beverages Prepared Using Passion Fruit (Passiflora edulis) and Apple (Malus pumila)”
Increased antioxidants and phenolic compounds produced in salted red perilla leaves during Japanese apricot pickling
Antioxidant content and activity are increased during the processing and digestion of Japanese apricots pickled with salted red perilla leaves
Chiba University
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Sampling was conducted at three stages: during simple salt pickling, after 30 days of pickling with salted perilla leaves, and after 60 days of pickling with salted perilla leaves. The resulting Shiso-zuke Umeboshi had a distinctive red appearance.
view moreCredit: Prof. Yukiharu Ogawa from Chiba University
The diverse biochemical composition of Japanese apricot fruits explains their broad spectrum of action on the human body. The high levels of key phenolic compounds and hydroxycinnamic acids contribute to various health benefits including anti-inflammatory, antioxidant, and antimicrobial properties.
A recent study published in Food Research International on July 19, 2024, led by Prof. Yukiharu Ogawa and Jutalak Suwannachot from Chiba University, quantitatively evaluated the changes in phenolic compounds and antioxidant activity during the production of Shiso-zuke Umeboshi (PP). The study also simulated the digestive process to characterize the release of these compounds and their antioxidant activity.
“Some of the benefits have been observed in pickling with red perilla (PP), but the current data are still limited. Many recent efforts have been focused on creating functional foods, which are designed to provide health benefits and essential nutrients in addition to the traditional micronutrients. However, there remains uncertainty regarding the specific effects of apricot pickled with red perilla (Shiso-zuke Umeboshi, PP). This motivated our study,” explains Prof. Ogawa.
In this study, the production of perilla-pickled apricots involved three methods: simple salt pickling (SP), pickling with salted perilla leaves for 30 days (30-PP), and pickling with salted perilla leaves for 60 days (PP). The pickle samples underwent ultrasonic-assisted treatment, after which the supernatants were extracted from the mixture by centrifugation to quantify free and esterified phenolics in the aqueous phase. The remaining residue was used to analyze the insoluble-bound phenolics in the organic phase.
All three phenolic fractions were assessed using liquid chromatography-mass spectrometry (HPLC-PDA-QDa), with a focus on their peak areas at 280 and 320 nm wavelengths.
The researchers evaluated total phenolic content (TPC) using the Folin-Ciocalteu reagent test. The Total flavonoid content (TFC) was determined via a 96-well microplate method combined with an aluminum chloride (AlCl3) colorimetric assay. Antioxidant activity was then assessed at 740 nm, with results expressed in millimoles (mmol).
The scientists modeled the gastrointestinal digestion of apricot pickles. They adjusted the sample’s pH to simulate the conditions of the different parts of the digestive tract. Next, digestive enzymes were introduced, and the digested fractions were filtered. The components were then identified, and their antioxidant activity was measured.
The HPLC chromatogram revealed rosmarinic, caffeic, p-coumaric, and ferulic acids as the main phenolic compounds detected. A comparative analysis of the three samples showed an increase in the concentration of bioactive compounds from the 30-day pickling stage (30-PP) to the finished product (PP). Among all phenolics, rosmarinic acid (RA) was the most predominant in all the samples. Ferulic acid was detected in smaller concentrations, particularly in esterified fractions that also showed higher levels of caffeic and p-coumaric acids. The lower concentration of ferulic acid is likely due to its low water solubility.
In the simulated in vitro digestion, differences between salt pickling (SP) and salt pickling with perilla (PP) were analyzed at various stages: before digestion (G0), 60 minutes after gastric digestion (G60), at the transition to intestinal digestion after 60 minutes (G60), and 120 min into small intestinal digestion (I120).
The highest release of bioactive compounds occurred at G0, while the lowest levels were observed at G60. However, a significant increase in bioactive compound release was noted between G60 and I120. At I120, both SP and PP showed the highest release of TPC and TFC. These results can be attributed to the influence of pH conditions and intestinal enzymes, which likely enhanced TPC and TFC levels.
For antioxidant activity, PP demonstrated a higher potential throughout the in vitro gastrointestinal digestion from 1 hour of gastric digestion through the final stage of small intestinal digestion, in contrast, SP exhibited a more steady trend. Overall, the acidic conditions during pickling appear to enhance the availability of RA and other perilla compounds.
“The health benefits of Japanese apricot pickles are mainly derived from the antioxidant compounds of the red perilla, which acts as both a natural food color and a health-promoting ingredient,” concludes the lead researcher Jutalak Suwannachot.
About Professor Yukiharu Ogawa
Yukiharu Ogawa is a Professor at the Graduate School and Faculty of Horticulture, Chiba University, Japan. He has previously held positions at National Food Research Institute in Tsukuba, the USDA Western Regional Research Center in California as a post-doctoral fellow, and at Kurashiki-Sakuyo University as a lecturer. The main area of his scientific work is agricultural and food process engineering, with a specific focus on food quality evaluation. His work aims to understand the impact of postharvest, food processing, and cooking procedures on the digestibility of processed food materials using simulated in vitro digestion techniques. He is also involved in developing long-term storage methods for fresh-cut vegetables and fruits monitored using atmospheric and lighting parameters.
Journal
Food Research International
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Changes in polyphenolic compounds and antioxidant activity of Japanese pickled apricot with salted red perilla leaf during pickling and digestion process
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