Optimizing Heat Treatment of Fruit Juices: Ensuring Quality Through Reduced Temperature

Abstract

This study evaluated the efficacy of reduced-temperature pasteurization in preserving the nutritional, sensory, and microbial integrity of two fruit juice products: a standard orange juice and a probiotic mango juice enriched with Lactiplantibacillus plantarum 299v, conducted at Österlenmejeriet AB in Lunnarp, a subsidiary of Danone. Laboratory-scale thermal treatments were applied at temperatures ranging from 70°C to 90°C with varying holding times. In orange juice, complete microbial inactivation was achieved at temperatures ≥80°C, while lower temperatures (e.g., 75°C for 45 seconds) effectively minimized vitamin C degradation and better preserved sensory attributes such as taste and aroma.
In probiotic mango juice, microbial safety was maintained across all conditions, with no detectable levels of Enterobacteriaceae, yeasts, or molds. Importantly, probiotic viability remained above the therapeutic threshold (10⁷ CFU/mL) in treatments up to 85°C, with a notable decline observed at 90°C. Vitamin C degradation exhibited a positive correlation with both temperature and exposure time. The lowest degradation occurred at 70°C, where vitamin C loss remained below 5.2 mg/100 g even after 120 seconds. In contrast, degradation exceeded 7.5 mg/100 g at 90°C after just 20 seconds, indicating a rapid reduction of ascorbic acid content under severe thermal conditions. Post-thermal processing, °Brix values generally remained stable or slightly increased, with the final increment in probiotic mango juice attributed to soluble solids from the added oat base. Similarly, a slight pH increase (decrease in acidity) was observed post-treatment, particularly above 80°C. Additionally, vitamin C retention during storage was significantly higher in samples treated below 80°C. °Brix and pH remained stable across processing and storage, indicating overall product quality preservation.
These findings demonstrate that optimized sub-pasteurization treatments can achieve microbiological safety while enhancing nutritional and functional quality in juice products, supporting their industrial application and sustainability goals.

Popular Abstract

Enhancing Juice Quality Through Gentle Pasteurization
Bringing Healthier, Tastier, and Safer Juices to Consumers and Industry
This research explored how fruit juice processing can be optimized to meet growing consumer and industry demands for safer, more nutritious, and environmentally sustainable beverages. Focusing on two commercially produced beverages standard orange juice and probiotic mango juice enriched with Good bacteria used to support digestive and immune health (A well-known probiotic strain). The study evaluated the effects of reduced-temperature pasteurization (70°C to 90°C) at various holding times on making the juice safe from harmful bacteria, preserving vitamin C, maintaining taste and texture, and keeping the good bacteria alive.
Results showed that while making the orange juice completely free from harmful bacteria required temperatures of 80°C or higher, gentler treatments like 75°C for 45 seconds did a much better job of protecting vitamin C and preserving flavor and aroma leading to a more nutritious and better-tasting juice. In the probiotic mango juice, which mixed with oat base included beneficial bacteria, safety was upheld in all treatments, with no signs of harmful bacteria which indicators of poor hygiene and any unwanted or risky of potentially harmful microbes. Moreover, the amount of beneficial bacteria stayed above the level considered effective for gut health in treatments up to 80°C, with the highest survival seen at 80°C for 15 seconds making it an ideal condition for keeping the health benefits of the probiotic drink. The study also showed that sugar levels and acidity stayed mostly stable, with slight increases in the probiotic mango juice linked to the oat base, which added nutrients and helped balance the juice’s acidity. Importantly, probiotic mango juices processed below 80°C not only kept more of their vitamin C content during 46 days of storage but also needed gentler heating, which directly translates to reduced energy use and potential cost savings in large-scale production. By avoiding unnecessary high-temperature treatments, manufacturers could still ensure the product is safe from harmful microbes and remains fresh over time, all while using less energy with fewer resources, supporting sustainability goals and potentially lowering the final cost. These findings support a shift toward more energy-efficient, lower-impact pasteurization processes that preserve product quality, improve shelf life, and enhance the commercial viability of functional beverages all critical factors in an increasingly competitive and environmentally conscious market.

• author: Sarlak, Shahram
• supervisor: Åsa Håkansson; Ulf Schönström; Andreas Håkansson
• organization: Food Technology and Nutrition (M.Sc.)
• course: KLTM02 20251
• year: 2025
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering; Agriculture and Food Sciences
• keywords: Food engineering nutrition and food chemistry, reduced-temperature pasteurization, vitamin C retention, probiotic viability, thermal processing, fruit juice quality, microbial safety, probiotic mango juice, prange juice processing
• language: English
• id: 9202862
• date added to LUP: 2025-06-23 09:07:21
• date last changed: 2025-06-23 09:07:21