The thermal processing of tomato ( Solanum lycopersicum L. ), both at home and commercially, is key for obtaining derivatives, such as preserves, sauces, pastes, and purees, consumed worldwide. Therefore, in this study, the effects of different heat treatments, such as frying, blanching, and cooking, on the physicochemical parameters and antioxidant properties of yellow plum tomato ( S. lycopersicum L., var. Blondkopfchen ) were evaluated. The conditions used were frying in vegetable oil (150 ± 5 °C, 3 min), blanching in water (90 ± 2 °C, 5 min), and cooking in water (95 ± 2 °C, 10 min) compared to fresh fruit. Heat treatments showed significant differences ( p < 0.05) in physicochemical and antioxidant properties compared to fresh tomatoes. Regarding color, increases in the yellowness index were observed in all heat treatments. Frying resulted in the highest total carotenoid content (3.35 mg/100 g), and antioxidant activity (AA) [15.52 mmol Fe + 2 /100 g and 46.59% 2,2-diphenyl-1-picrylhydrazyl (DPPH)] compared to the fresh sample, which had values of 2.07 mg/100 g, 9.63 mmol Fe + 2 /100 g, and 32.24% DPPH, respectively. Blanching resulted in the lowest loss of total phenolic content (8.34 mg GAE/100 g) compared to the other methods, while cooking resulted in the lowest loss of vitamin C (48.58 mg/100 g) compared to the other methods. It can be concluded that frying is the best treatment for increasing the ash, ether extract, total carotenoid content, and AA content in plum tomatoes compared to the other methods. Blanching and cooking allow for a higher concentration of preservation of total phenolic compounds and vitamin C compared to frying. This information is relevant for optimizing production processes and promoting the use of this little studied variety in the food industry.
Foam layer drying is an alternative to conventional dehydration methods due to its ability to reduce thermal damage and preserve bioactive compounds of different food matrices. This study aimed to evaluate the physical, chemical, and microbiological characteristics of tropical fruit powders (watermelon, guava, pineapple, and acerola) obtained by foam layer drying using a combined system of powdered egg white albumin and carboxymethylcellulose. The fruit pulps were processed, foamed, and dried at 68 °C for 6 h, and the resulting powders were characterized in terms of hygroscopicity, density, flowability, water and oil retention capacity, color, moisture, water activity, phenolic and carotenoid compound profiles, antioxidant capacity, microbiological quality, and antimicrobial activity. The powders showed low moisture (2.8–3.6%) and water activity (0.18–0.22), excellent flowability, low hygroscopicity (1.28–3.66%), and favorable functional properties. High levels of phenolic and carotenoid compounds were preserved, resulting in pronounced antioxidant activity. All samples met the microbiological standards stipulated in the legislation, showing an absence of pathogenic bacteria and low microbial counts. Limited and selective antimicrobial activity was observed in the hydroethanolic extracts. Overall, foam drying proved to be an efficient and robust technology for the production of tropical fruit powders rich in bioactive compounds, with great potential for application as functional ingredients.
Milk beer originated in China and is a widely popular refreshing dairy beverage. Its distinctive flavor primarily stems from Kluyveromyces marxianus used during fermentation. However, the current high-density fermentation process for this yeast strain remains constrained by a dry weight yield of 70 g/L, coupled with relatively high production costs. These factors limit the application of yeast in the production of milk beer. This study aims to establish a high-density cultivation process and feeding regimen for Kluyveromyces marxianus to enhance its viable cell count and dry weight, thereby evaluating its applicability in milk beer production. First, the optimal cultivation conditions for the Kluyveromyces marxianus MK5 strain were determined in a 5 L fermenter, which was then used for fed-batch fermentation. Subsequently, the resulting milk beer was compared with milk beer produced using the commonly used Kluyveromyces marxianus MJ strain and a blank acidified milk solution. Results indicated that simulated exponential fed-batch fermentation at a specific growth rate of 0.05 h −1 significantly promoted MK5 growth. The maximum viable cell count reached 1.88 × 10 10 colony-forming unit/mL during cultivation, with a dry cell weight of 113.7 g/L. Furthermore, milk beer samples fermented with strain MK5 demonstrated significant advantages in enhancing milk beer stability and improving flavor.
Bananas are rich in hydrocolloids, primarily pectic polysaccharides, which play a crucial role in determining their textural and rheological behavior. These quality properties, which may be influenced by banana varieties and ripening conditions, are very important for fruit purees. This study investigated the impact of variety and ripening agents on the rheological and textural properties of banana puree. Three varieties “Kluai Hom Thong,” “Kluai Namwa,” and “Kluai Leb Mue Nang” and two ripening agents, ethephon and CaC 2 , were used in this study. Purees developed were analyzed for textural and rheological properties. Although all samples exhibited shear-thinning behavior (n < 1) typical of fruit purees, varietal differences predominated over treatment effects. “Kluai Namwa” had the highest consistency (K = 49.06–63.06 at the fully ripe stage; K = 28.11–45.29 at the overripe stage) and flow behavior (n = 0.31–0.36 at the fully ripe stage; n = 0.23–0.29) compared with the other varieties. Firmness (77.98–82.59 g at the fully ripe stage; 45.86–49.91 g at the overripe stage) and cohesiveness (−65.68 to −73.06 g at the fully ripe stage; −27.72 to −35.87 g) were also highest in the ‘Kluai Namwa’ variety. The ‘Kluai Namwa’ variety showed greater rheological strength and solids content, while ‘Kluai Leb Mue Nang’ was characterized by higher cohesiveness and structural integrity, and “Kluai Hom Thong” by softer, weaker texture. Ethephon and CaC 2 treatments generally reduced work of cohesion and other textural parameters, especially at the overripe stage. Principal component analysis (PCA) further revealed clear varietal separation but minimal differences between ripening treatments and controls. Overall, varietal composition rather than ripening agent determined the structural and flow behavior of banana purees, highlighting intrinsic matrix differences as the primary drivers of puree texture.
Brazil holds a prominent position in the global fig market, with production mainly based on the cultivar ‘Roxo de Valinhos’. However, the high perishability of the fruit limits its distribution and postharvest conservation. In this context, the use of technologies that support fruit preservation becomes essential. Chitosan stands out for forming a natural biofilm that protects fruits against pathogens, in addition to reducing gas exchange and water loss. The aim of this study was to evaluate the application of different chitosan concentrations for the preservation of ‘Roxo de Valinhos’ figs during cold refrigerated storage. The experimental design was completely randomized in a split-plot arrangement, with five chitosan concentrations and five evaluation times. During refrigerated storage, chitosan-coated figs showed reduced deterioration, with up to 78% reduction in fruit decay compared with the control. The 1.2% coating delayed firmness loss, maintaining fruit firmness at 0.60 N after 20 days, compared with 0.52 N in untreated fruits. In addition, chitosan treatments reduced sugar accumulation, with 1.2% chitosan limiting reducing sugar increase to 29.09%. The preservative action of the biofilm was evidenced by correlation analysis, which associated coated fruits with better maintenance of physicochemical characteristics during storage. Correlation analysis indicated the preservative effect of the biopolymer, associating coated fruits with improved maintenance of physicochemical quality indicators during storage.
