The Effects of Stress Factors on the Growth of Spoilage Yeasts Isolated From Apple‐Related Environments in Apple Juice

Abstract

This study aimed to evaluate the effects of temperature, pH, sugar content and antimicrobial components on the growth of 11 yeast isolates in apple juice (12°B rix, pH 4.0). The results showed that reduction of the storage temperature to 4C could achieve a complete inhibition of test strains, and the temperature required to kill all the initial yeast inoculum (10 3 cfu/mL) within 20 min ranged from 46 to 55C, depending on the isolate. However, high sugar content enabled test strains to survive in what would have been a lethal treatment. A pH value below 2.0 had a significant inhibitory effect on the growth of test strains. Increasing the sugar content of apple juice was not enough to completely avoid the spoilage caused by the test strains, especially Zygosaccharomyces rouxii. Addition of antimicrobial components (4.0 mM sorbic acid, 1.5 mM cinnamic acid, 20 mM vanillin, 10 mM ferulic acid or 12 mM p-coumaric acid) was an applicable strategy to prevent the spoilage in apple juice spawned by the test strains. PRACTICAL APPLICATIONSWith the rapid improvement of living standards, there has been a considerable increase in the demand for better quality apple juice. Quality deterioration is a frequently reported problem in apple juice industry, which mainly resulted from microbial contamination, especially osmotolerant yeasts, that alters the original flavor by the production of new odor-active metabolites. Therefore, development of effective strategy to prevent the spoilage is an important issue. Stress factors including temperature, pH, sugar content and antimicrobial components are all used to inhibit yeast species and other microorganisms in food. Study of the effects of these factors on the growth of yeasts is advantageous to extend the microbial stability of apple juice during storage. The results show that addition of antimicrobial components, applicable to apple juice industry, is sufficient to extend the shelf life of apple juice for more than 50 days.

Metabarcoding analysis and fermentation performance of the dominant fungal microbiota associated with the Algerian traditional date product “Btana”

“…Regarding biochemical tests, results shown in Table 2 indicate that all the species are osmo-tolerant and grow well in 50 and 60% glucose broth. Zygosaccharomyces rouxii was the most osmoresistant yeast, which is consistent with an earlier study that had reported that the species can support sugar content as high as 70°Brix (approximately 875 g/l glucose) and is able to grow at water activities as low as 0.60 (Wang et al 2016;Marvig et al 2015). It is admitted that this feature of osmotolerance is linked to the production of compatible solutes (i.e., polyols) such as D-arabitol according to many authors (Sharma and Sharma 2017;Evrendilek 2012).…”

“…The viability feature is a key element for biotechnological process involving recycling or re-circulation. In this respect, Wang et al (2016) reported that non-Saccharomyces species found in fermented food could be isolated only from the early stages of fermentation. Therefore, the studied strains isolated from Btana are promising candidates in fermentation process as they can sustain under extended periods of fermentation and high ethanol stress.…”

Antifungal activities and mechanisms of trans‐cinnamaldehyde and thymol against food‐spoilage yeast Zygosaccharomyces rouxii

“…This result suggests that all Z. rouxii strains tested are susceptible to THY and T-CNM, and THY has a better antifungal activity against Z. rouxii. In comparison with other antifungal agents, THY showed better fungistatic and fungicidal activities against Z. rouxii than ferulic acid (MIC of 1.17 mg/ml), p-coumaric acid (MIC of 1.23 mg/ml), cinnamic acid (MIC of 0.35 mg/ml), vanillin (MIC more than 2.28 mg/ml), citral (MIC of 0.17 mg/ml and MFC of 0.34 mg/ml), limonene (MIC of 0.66 mg/ml and MFC of 2.64 mg/ml), carvacrol (MIC of 0.128 mg/ml), eugenol (MIC of 0.43 mg/ml and MFC of 0.86 mg/ml), and potassium metabisulfite (MIC more than 0.256 mg/ml) (Cai et al, 2019;Chavan & Tupe, 2014;Wang et al, 2016b). In another report, THY exhibited better inhibitory activity against the growth of Z. rouxii in apple juice (30 • Brix) than T-CNM, carvacrol, hydroxycinnamic acids, and synthetic preservatives (potassium sorbate and sodium benzoate) (Wang & Sun, 2020).…”

Changes of Quality of Minimally-Processed Pineapple (Ananas comosus, var. ‘Queen Victoria’) during Cold Storage: Fungi in the Leading Role

“…can occasionally be isolated from low-pH juices [55,56]. On the opposite, R. mucilaginosa and S. cerevisiae are commonly involved in the spoilage of fruit products [48,51,57,58]. M. caribbica is mostly known as an endophyte yeast, but has been isolated from spoiled minimally-processed pineapple [26,59].…”