Fresh-cut fruit is unusually difficult to preserve because cutting breaks the protective skin and exposes cells to oxygen, enzymes and microorganisms. In apples, tissue disruption allows polyphenol oxidase and peroxidase to contact phenolic compounds. These enzymes convert phenolics into quinones, which then react and polymerize into the brown pigments familiar on cut apple surfaces. At the same time, water loss accelerates, cell walls weaken and fungi can colonize the damaged tissue. Species including Penicillium expansum, Penicillium chrysogenum, Botrytis cinerea, Fusarium oxysporum, Aspergillus flavus and Aspergillus niger are associated with postharvest spoilage. Some fungi can also produce mycotoxins, making deterioration more than a cosmetic problem. The authors note that global apple losses can reach roughly one-quarter of production, underscoring the need for preservation methods that control several forms of deterioration at once.

The team first tested extracts made with solvents of different polarity to determine which one recovered the most active compounds from dried A. bisporus. Ethanol performed best, producing the broadest antifungal effects and an inhibition zone of 14 millimeters against P. chrysogenum in a disc-diffusion assay. The researchers then dried mushrooms at 45 degrees Celsius, ground them into a fine powder and exposed separate batches to gamma-radiation doses of 0, 2, 4, 6 or 8 kilograys. Gamma radiation is high-energy electromagnetic radiation capable of breaking chemical bonds and altering biological materials. In a food matrix, moderate exposure can disrupt cellular structures and release compounds that were previously bound within the tissue. It can also chemically transform existing molecules. But the same chemistry can become destructive at excessive doses, oxidizing or fragmenting sensitive compounds. The study therefore treated radiation dose as a variable to optimize, not simply as a higher-is-better intervention.

The strongest overall response occurred at 6 kilograys. At that dose, the extract contained 3.25 milligrams of gallic acid equivalents per gram, compared with 2.12 milligrams per gram in the non-irradiated control. The Folin–Ciocalteu measurement used by the researchers is an estimate of total phenolic content, expressed relative to gallic acid as a standard. Phenolic molecules are important because their hydroxyl groups can donate electrons or hydrogen atoms to reactive radicals, helping terminate oxidative chain reactions. Consistent with the chemical measurement, the irradiated extract neutralized 46.3 percent of the DPPH radical at a concentration of 100 micrograms per milliliter, compared with 40.9 percent for the untreated extract. The synthetic antioxidant TBHQ produced 96.8 percent inhibition under the same test conditions, showing that the mushroom preparation was not equivalent to a highly active purified antioxidant but nevertheless gained measurable activity through irradiation. At 8 kilograys, both phenolic content and antioxidant performance declined, supporting the idea that overexposure degraded sensitive compounds.

The antifungal experiments produced the same dose-dependent pattern. Extracts from irradiated mushrooms inhibited all six tested apple-spoiling fungi, with activity increasing through 6 kilograys and then falling at 8 kilograys. Against P. expansum, the inhibition zone expanded from 11.3 millimeters in the control extract to 16.3 millimeters after 6-kilograys treatment, an increase of about 44 percent. P. chrysogenum showed the largest response, with its inhibition zone reaching 20.3 millimeters, compared with 13.7 millimeters for the non-irradiated extract. The 6-kilograys preparation also produced zones of 17.3 millimeters against F. oxysporum, 16.3 millimeters against B. cinerea, 14.7 millimeters against A. flavus and 18.3 millimeters against A. niger. In each case, the response weakened at 8 kilograys. Statistical analysis indicated that radiation dose significantly affected inhibition-zone diameters, although the tests were conducted in triplicate and remain laboratory assays rather than evidence of commercial-scale performance.

Additional experiments provided clues about how the extract damages fungi. In a sorbitol-protection assay, the minimum inhibitory concentration of the irradiated extract increased when the growth medium contained 0.8 molar sorbitol. Sorbitol acts as an osmotic stabilizer: it can partially compensate for damage to a fungal cell wall, allowing a weakened cell to survive exposure that would otherwise stop growth. A shift in the minimum inhibitory concentration therefore suggests that the extract interferes with wall integrity. The researchers also found that the 6-kilograys extract reduced the activity of fungal extracellular enzymes, cutting protease activity by about 40 percent, cellulase by 35 percent and lipase by 45 percent. These enzymes help pathogens digest host tissues. Electron microscopy reinforced the biochemical results. Untreated hyphae appeared smooth, turgid and regularly branched, whereas treated fungi displayed collapsed hyphae, shrunken surfaces and deformed spores, with particularly pronounced effects in B. cinerea and P. expansum. Together, the results suggest a multifactorial mechanism involving cell-envelope damage and suppression of tissue-degrading metabolism.

Chemical profiling offered a possible explanation for the enhanced bioactivity. Using gas chromatography–mass spectrometry, the researchers detected changes in fatty acids and sterols after irradiation. The extract contained linoleic acid and related compounds, along with ergosterol and neoergosterol derivatives. At 6 kilograys, the relative abundance of sterols and medium-chain fatty acids increased compared with the non-irradiated material. Ergosterol rose from 1.03 percent to 3.09 percent, while some compounds, including neoergosterol and estra-1,3,5(10)-trien-17β-ol, appeared only after irradiation. These measurements describe relative abundance in the analyzed extract, not necessarily an increase in the total amount of each compound. Still, the altered chemical profile is consistent with radiation-induced breakdown, rearrangement and release of mushroom metabolites. Sterols and phenolics can affect fungal membranes and cell walls, while changes in the availability of bound compounds may help explain why moderate radiation strengthened activity. At higher doses, however, oxidation and polymerization may destroy the same molecules that contribute to antimicrobial effects.

The researchers next tested whether the optimized preparation worked on real fruit rather than only in culture plates. They cut apples into two-centimeter-thick slices and dipped them for three minutes in either water, a 10 percent weight-to-volume solution of non-irradiated mushroom extract or the same concentration of extract made from mushrooms treated at 6 kilograys. The slices were stored at approximately 4 degrees Celsius for 10 days. By the end of storage, untreated apples had lost 6.2 percent of their initial mass, while slices treated with non-irradiated and irradiated extracts lost 4.2 and 3.0 percent, respectively. Firmness also declined in all groups, but the irradiated-extract treatment slowed the loss: control slices fell from 15.5 newtons initially to 10.0 newtons after 10 days, whereas treated slices retained 12.5 newtons. The extract may have formed a thin protective layer that limited water transfer, while its antioxidant and enzyme-inhibitory effects may have helped stabilize cell-wall structures.

The most visible benefit was reduced discoloration. Apple slices coated with the irradiated extract maintained lower color change and browning-index values than both untreated slices and those given the non-irradiated preparation. By limiting oxidative reactions, phenolic compounds could reduce the accumulation of quinones that generate brown pigments; antioxidant molecules may also interfere with the reactive oxygen chemistry that sustains browning. After 10 days, the treated apples had about 1.3-log fewer fungi and yeasts and 1.6-log fewer bacteria than the control, reductions that correspond to roughly 20-fold and 40-fold decreases, respectively, on a base-10 scale. The authors report no visible off-odors or obvious tissue damage, but the study did not include a formal sensory panel or flavor analysis. Nor did the storage experiment deliberately inoculate apples with individual pathogens. The microbial results therefore reflect natural contamination conditions, while the pathogen-specific evidence comes primarily from laboratory assays.

The findings do not yet establish that irradiated mushroom extract is ready to replace commercial apple preservatives. The study used a limited number of independent batches and a relatively short storage period, and larger trials will be needed to determine consistency across apple varieties, harvest conditions and industrial handling systems. Researchers must also assess taste, aroma, consumer acceptance, extract stability, production cost and regulatory requirements. Controlled challenge tests could reveal how effectively the coating works against P. expansum and B. cinerea directly on fruit, while further experiments are needed to determine whether it affects mycotoxin production. The authors describe such investigations as ongoing. Even with these caveats, the work demonstrates an intriguing form of chemical tuning: moderate gamma irradiation did not simply sterilize the mushroom material, but altered its extractable chemistry and biological performance. If those effects can be reproduced safely and economically, an ordinary edible mushroom could become the source of a multifunctional coating designed to keep cut fruit fresher for longer.

Probiotics are live microorganisms that, when consumed in adequate amounts, confer health benefits to the host. One of the most well-researched strains is Lactiplantibacillus plantarum, which is renowned for its positive impact on gut health. This strain helps in the modulation of the gut microbiota, enhancing digestion, and potentially alleviating gastrointestinal disorders. However, maintaining the efficacy of probiotics in commercial products remains a significant challenge due to environmental stressors that can diminish their viability.

The innovative technique developed in this study employs alginate, a biodegradable polymer derived from brown seaweed, known for its gel-forming capabilities. The researchers have combined this polymer with the protective qualities of fruit juice to create microencapsulated beads that safeguard the probiotic bacteria from harsh storage conditions. This dual approach not only protects the cells but also opens avenues for flavor diversification and nutritional enhancement in the final fermented product.

The encapsulation method offers a myriad of benefits. It creates a barrier that shields Lactiplantibacillus plantarum B7 from detrimental factors such as pH changes, oxygen exposure, and temperature fluctuations, which are common during storage and transportation of fermented foods. Furthermore, fruit juice coatings can provide antioxidants that bolster cell viability, a significant improvement over non-encapsulated probiotics, which typically have high mortality rates under adverse conditions.

During the experiments, the researchers observed an impressive enhancement in the viability of Lactiplantibacillus plantarum B7 throughout the storage period. While traditional fermented milk products often see a decline in probiotic populations, the microencapsulated version maintained robust cell counts, indicating its potential for commercial use. Additionally, this technique showed a marked increase in GABA production, a compound that has garnered attention for its neuroprotective and anxiety-reducing properties.

GABA is a naturally occurring neurotransmitter that plays a crucial role in regulating brain activity. Elevated levels of GABA are associated with various health benefits, including reduced anxiety, improved sleep, and increased mood stability. This research highlights the potential for enhancing the nutritional profile of fermented dairy products through the strategic cultivation of well-studied probiotic strains capable of producing significant amounts of GABA.

The results of this study have far-reaching implications for both the dairy industry and consumers. For manufacturers, the ability to produce stable, probiotic-rich products with enhanced health benefits opens new markets and consumer bases. For consumers, availing of fermented milk products fortified with both beneficial bacteria and a natural, functional compound like GABA presents a compelling health choice.

Moreover, this research aligns with a growing trend towards functional foods—products that provide health benefits beyond basic nutrition. As consumers become increasingly aware of the importance of gut health and overall well-being, the incorporation of multi-functional probiotics such as Lactiplantibacillus plantarum B7 into popular food items could satisfy demand while improving public health outcomes.

The study’s findings could lead to broader applications in the food industry, beyond mere fermented milk. Enriching a variety of dairy and non-dairy products with encapsulated probiotics could create new possibilities for healthy snacks, beverages, and even supplements. This would not only improve product efficacy but also cater to a range of dietary preferences and restrictions, including vegan-friendly options with plant-based alginate.

This research paves the way for future innovations in food preservation and nutritional enhancement, encouraging further exploration of natural encapsulation methods. By leveraging the properties of fruits and other plant materials, food scientists may discover novel ways to improve health benefits while respecting consumer demand for natural ingredients.

In conclusion, this study spearheaded by Pannerchelvan, Jawlan, and Wasoh marks a significant advancement in the understanding and implementation of probiotics in food technology. By effectively enhancing cell viability and GABA production through an innovative encapsulation strategy, researchers lay the groundwork for developing healthier, more functional fermented products that cater to modern consumer needs. The approach exemplifies the intersection of science and culinary arts, promising to elevate the standards of food quality and health benefits for years to come.

Subject of Research: Enhancing cell viability and GABA production in fermented milk using fruit juice-coated alginate microencapsulated Lactiplantibacillus plantarum B7 during storage.

Article Title: Enhancing cell viability and GABA production in fermented milk using fruit juice-coated alginate microencapsulated Lactiplantibacillus plantarum B7 during storage.

Article References: Pannerchelvan, S., Jawlan, L.L.L., Wasoh, H. et al. Enhancing cell viability and GABA production in fermented milk using fruit juice-coated alginate microencapsulated Lactiplantibacillus plantarum B7 during storage. Int Microbiol (2025). https://doi.org/10.1007/s10123-025-00662-7

Image Credits: AI Generated

DOI: https://doi.org/10.1007/s10123-025-00662-7

Keywords: Lactiplantibacillus plantarum, GABA, probiotics, fermented milk, alginate microencapsulation, fruit juice, gut health, functional foods.

Hummus has surged in popularity across the globe, yet its consumption has been fraught with safety concerns. Between 2000 and 2018, there were reported cases of 20 illness outbreaks linked to hummus in the United States, resulting in 65 hospitalizations and five fatalities. Such alarming figures prompted many commercial brands to turn to chemical preservatives as a means to prolong shelf life and mitigate foodborne illness risks. Even though these chemicals may enhance the product’s longevity, they also raise questions regarding food safety, health impacts, and consumer preferences for more natural ingredients.

The crux of the WSU research revolves around two distinct microwave processing techniques: microwave-assisted pasteurization and microwave-assisted sterilization. Each method employs electromagnetic energy to achieve food safety with varying levels of intensity. The former is a milder treatment that not only preserves the organoleptic qualities of hummus—like taste and texture—but also allows for refrigeration storage for up to a month when unopened. In contrast, the latter technique, while harsher and less flavor-preserving, extends the shelf life significantly, allowing the hummus to remain safe for consumption at room temperature for up to two years if left unopened.

The underlying technology was developed by Juming Tang and his dedicated research team at WSU. They have been focused on using microwave energy to efficiently kill food pathogens while maintaining the nutritional quality of the food. These microwave methodologies permit rapid and uniform heating, thereby minimizing the risk of overcooked or unevenly heated food. Traditional preservation methods, such as canning, often compromise flavor and texture in the quest for safety, but microwave processing presents a solution devoid of such sacrifices.

Shyam Sablani, the lead investigator on the project, expressed enthusiasm about the findings, emphasizing that both processes maintained high quality in terms of storage, texture, and sensory attributes. This was evident in Sablani’s own tasting trials, where he described the final product as “very good,” effectively dispelling any preconceived notions about the potential downsides of using microwave technology in food processing.

Interestingly, WSU’s researchers took an unconventional route by creating a lentil-based version of hummus instead of the traditional chickpea recipe. This switch arose from the insights of visiting researcher Burcu Tenderis, who noted that lentils were commonly utilized in certain regions of Turkey. Lentils, known for their economic advantages and availability in the U.S., provided a unique opportunity to explore other flavor profiles while investigating alternative ingredients that are more sustainable.

In addition to the nutritional and preservation benefits, the team focused on enriching the hummus with vitamin C, a critical nutrient that is often significantly reduced during cooking processes. By measuring the vitamin retention post-treatment, researchers found that the microwave technology managed to retain an impressive 75% of vitamin C in the final product. This outcome points toward the potential for developing healthier snack options that do not compromise on nutritional value.

The next phase of the research aims to gather qualitative feedback by having panels assess their experiences regarding taste, aroma, and overall satisfaction with the product. This step is vital not only for consumer acceptance but also for ensuring that the final product aligns with market preferences and health standards.

This project was part of the Soil to Society program, which aims to enhance public access to nutritious foods derived from grains and legumes. The collaboration has allowed for crucial advances in the research, though Sablani now seeks industry partners to assist in scaling the production for consumer markets. If progress in commercialization is realized, it could mark a significant achievement in the food industry by bridging the gap between nutrition, safety, and taste.

While the commercialization process will likely require several years of development and marketing, the excitement surrounding this research is infectious. Ensuring that foods remain safe and shelf-stable while providing essential nutrients is more important than ever, especially in a world where food security is a growing concern.

The potential implications of this research extend far beyond the humble chickpea and lentil hummus. By pioneering microwave technologies that resonate with today’s health-conscious consumers, WSU is setting a precedent for how the food industry can innovate for enhanced safety, improved quality, and greater consumer appeal in the realm of perishable items.

The diligent work of WSU researchers represents a potential turning point in food processing, enabling the evolution of traditional recipes into modern, health-oriented products. The shift towards natural food preservation methods may not only herald a healthier future for consumers but also drive forward-thinking innovations in food technology.

In essence, the drive to improve food safety while enriching nutritional quality is a testament to the relentless pursuit of better food practices. As WSU continues to navigate this intersection of science, health, and culinary tradition, it opens a world of possibilities for future explorations and innovations.

By employing microwave technology in food preservation, this research project may very well redefine how we think about food safety and shelf stability, encouraging a movement toward healthier, preservative-free options available for all.

Subject of Research: Development of Vitamin C-Enriched Lentil Hummus
Article Title: Development of Vitamin C-Enriched Lentil Hummus With Innovative Microwave Technologies
News Publication Date: 12-Apr-2025
Web References: Journal of Food Process Engineering
References: Microwave Food Preservation Research
Image Credits: Photo courtesy of Burcu Tenderis

Keywords

Hummus, Microwave Technology, Food Safety, Shelf Life, Natural Preservation, Nutritional Value, Lentils, Vitamin C, Food Engineering, Washington State University