Probiotics remain potent in simple plant-based drinks

By Dr. Liji Thomas, MDReviewed by Lauren HardakerJun 24 2025

In a first-of-its-kind test, scientists show that non-encapsulated probiotics can thrive in fruit and vegetable juices, staying fresh, flavorful, and functional from shelf to sip.

Study: Developing Novel Plant-Based Probiotic Beverages: A Study on Viability and Physicochemical and Sensory Stability. Image credit: Aninka Bongers-Sutherland/Shutterstock.com

Probiotics have soared in popularity because of their health benefits. A recent study in Foods explored plant-based probiotic mixes for their stability and how well they appealed to consumers’ senses.

Introduction

Most commercial probiotic beverages are dairy-based. With the rise of veganism, milk allergy, and lactose intolerance, nondairy ‘clean’ probiotic beverages have become more necessary. Those based on fruits and vegetables are naturally rich in antioxidants and vitamins, enhancing immune function and gut health and improving the quality of life.

Fruit juices are considered healthy, taste good, and are popular at all ages, making them ideal probiotic options. Adding probiotics like Lactobacillus to these beverages results in a nondairy functional food considered healthy. The main challenge lies in keeping the probiotic alive at a concentration of 10⁶ CFU/mL or more throughout the product’s shelf life.

Fruits are high in organic acids, which can result in the loss of viability of probiotic cells over time under refrigerated conditions. The high sugar and salt content, metabolic activity, dissolved oxygen, and redox reactions in fruit juice increase this.

Furthermore, the fortified juices' sensory and physical characteristics (color, taste, smell, or clarity) could deteriorate during storage. Methods to overcome these issues include selecting strains with greater acid resistance, adding prebiotic fibers or polyphenols, probiotic cell microencapsulation, spray-drying, and freeze-drying.

Lactobacillus is a widely used probiotic genus, with strain-dependent stability varying also with the acidity and phenolic content. For instance, the strain L. casei DN-114001 survives for up to 12 weeks at 4 °C, whereas L. salivarius survives poorly after only two weeks of storage. Similarly, L. plantarum NCIMB 8826 was unstable in acidic media like cranberry and pomegranate juice, but not in orange and pineapple juice.

In the current study, a fruit and vegetable processing company supplied three 100% fruit or vegetable-fruit blends: ginger extract composed mostly of apple, a tropical fruit extract blend, and an avocado-containing blend. The blends contained combinations of ginger, avocado, apple, pear, pineapple, banana, mango, passion fruit, and spinach.

These were inoculated with three commercial Lactobacillus strains: L. reuteri, L. casei, and L. plantarum in their free form, at about 107 CFU/mL. Their survival, the stability of the juice, and their sensory quality were assessed over the primary and secondary shelf life.

Blends of fruit and vegetable extracts are popular with consumers that may synergize in their nutritional content, antioxidant capacity, and sensory appeal. The current analysis examined the viability of the selected strain in a medium like the commercial plant-based product.

Study findings

The study used three extracts with comparable sugar content. The ginger extract had the most significant carbohydrate percentage due to its higher fiber content. As expected, the avocado-containing extract had six times as much fat and more protein than the other two.

All were rich in phenolic compounds, the highest in the avocado extract, and flavonoids. The tropical extract had the highest levels of both. Thus, the probiotic was stable in the extract. The viable probiotic count did not alter significantly throughout the primary or secondary shelf life, remaining above 10⁶ CFU/mL in all tested combinations regardless of strain or matrix.

A literature-cited finding notes that malt-based extracts may promote Lactobacillus plantarum survival under refrigeration due to their high sugar content compared to wheat and barley extracts. This promotes ATP synthesis, key to cell viability at an acidic pH. Although malt was not tested in this study, the tested extracts contained 9 to 12% total carbohydrates, with 9 to 10% as simple sugar, capable of maintaining viability.

Physical and chemical stability

The pH of the probiotic-fortified samples remained stable throughout the shelf life, except for the avocado extract, which showed an increasing trend up to day 21. This is perhaps because naturally present vitamin C was broken down, or unsaturated fatty acids were oxidized.

Spoilage bacterial growth raises the pH. At an acidic pH, pathogen growth is inhibited. Thus, pH stability also confirms the efficacy of high-pressure processing for preservation.

However, after the pack was opened (secondary shelf life), the pH decreased for all extracts, probably because of the loss of sterility and the breakage of the modified atmospheric packaging (MAP). Despite refrigerated storage, both aerobic and acidophilic bacteria proliferated over these four days.

During this period, multiple factors interact to affect the pH. Titrable acidity (TA) varied with storage time in the ginger extract, the strain in the tropical extract, and both time and strain in the avocado extract. In the primary shelf life, only the avocado extract on day seven and the tropical extract on day zero showed statistically notable TA variation.

Color

While ginger extract remained chromatically stable over the shelf life, the others changed color over time, with mild, strain-specific shifts that normalized mainly by day 14. This study used a commercial E-Eye (Iris Visual Analyzer 400 system, Alpha M.O.S. Toulouse, France) that captured subtle but significant changes that escaped naked-eye observation.

This allows standardized assessment of color as a quality marker. It will also enable investigators to develop better formulations more appealing to the senses.

Volatiles profile

Combined, these extracts contained 165 volatile organic compounds (VOCs). These showed significant changes over time, depending on the strain and extract, such as increased terpenoids in the ginger extract. These alterations probably arise from various acid-catalyzed chemical reactions, microbial enzyme action, or secondary metabolites produced by the probiotics.

Acceptability

Tests of sensory appeal at 33 days from inoculation showed that the appearance, smell, flavor, taste, and aftertaste of all extracts remained appealing after probiotic addition. Mean panel scores ranged from 6.9 to 8.9 on a 9-point hedonic scale, based on 78 untrained volunteers. This suggests that high-pressure processing followed by cold storage preserves sensory attributes intact, unlike thermal treatment.

After leaving the pack open for a day, no change was identified except for one avocado extract sample. This improved in flavor over time as acids broke down, increasing the perception of sweetness.

Importantly, no significant difference in acceptability was observed between strains within the same juice matrix.

Conclusions

Probiotic-fortified fruit or vegetable juices may introduce “a new class of functional beverage that combines the health advantages of probiotics with the typical nutritional benefits of fruits and vegetables.” These maintain probiotic viability, remain safe for consumption, and retain their pleasant characteristics.

Importantly, no protective technologies were used. Future studies should compare unrestricted probiotic cell use with microencapsulation, which prolongs shelf-stable life and permits controlled delivery.

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