Enzyme assisted fermentation of potato pulp: An effective way to reduce water holding capacity and improve drying efficiency

Development of thermoultrasound assisted blanching to improve enzyme inactivation efficiency, drying characteristics, energy consumption, and physiochemical properties of sweet potatoes

Thermoultrasound (USB) as a promising alternative to traditional hot water (HWB) blanching was employed to blanch sweet potatoes and its influence on enzyme activity, drying behavior, energy consumption and physiochemical properties of sweet potatoes were investigated. Results showed that successive increases in blanching temperature and time resulted in significant (p < 0.05) decreases in PPO and POD activities. Compared to HWB, USB led to more effective drying by promoting texture softening, moisture diffusion, microstructure alterations, and microchannels formation, which significantly reduced energy consumption and improved the overall quality of the dried sample. Specifically, USB at 65 °C for 15 min improved water holding capacity and ABTS, while USB at 65 °C for 30 min improved color (more red and yellow), total phenolic content, total carotenoid content, and DPPH. Unfortunately, blanching process showed detrimental effects on the amino acid composition of dried samples. Overall, the development of thermoultrasound assisted blanching for sweet potatoes has the potential to revolutionize the processing and production of high-quality sweet potato products, while also improving the sustainability of food processing operations.

Moisture variation analysis of the green plum during the drying process based on low-field nuclear magnetic resonance

Green plums were dried at 50, 60, 70, and 80 ℃ to study the dynamic changes of internal moisture during the drying process. Low-field nuclear magnetic resonance (LF-NMR) was used to study the dynamic changes across the T₂ relaxation spectrum, while magnetic resonance imaging (MRI) provided visualization of the plums throughout the process. The results indicate a negative linear relationship between the lost moisture of the plums (p < 0.05) as drying time increased. Relaxation times T₂₁ , T_22, and T₂₃ , and the peak areas of A₂₁ and A₂₃ decreased significantly during the drying process. The MRI results also show that the brightness of the images decreased as the drying time increased, indicating that the higher the temperature, the greater the water loss inside the plums. Color measurements demonstrated that the high temperature dried plums had better sensory quality. Correlation analysis implies a strong positive relationship between A₂₃ and A_total and water content, with coefficients of 0.958 and 0.936, respectively. Principal component analysis results show that the drying temperature has a significant effect on the sample's internal moisture release. LF-NMR is a fast, convenient, and feasible technique for monitoring the moisture variation of green plums during the drying process. PRACTICAL APPLICATION: Low-field nuclear magnetic resonance (LF-NMR) was used to study the moisture dynamic changes of green plums across the T₂ relaxation spectrum, while magnetic resonance imaging (MRI) provided visualization of plums throughout the process. The drying temperature has a significant effect on the green plum's internal moisture release and may affect the quality of the plums. LF-NMR might be a complementary technique in monitoring the moisture variation of green plums during the drying process.

Autoclaving and extrusion improve the functional properties and chemical composition of black bean carbohydrate extracts

Common beans (Phaseolus vulgaris L.) are rich in starch with a high content of amylose, which is associated with the production of retrograded and pregelatinized starch through thermal treatments. The purpose of this study was to evaluate the composition, morphology, thermal, functional, and physicochemical properties of carbohydrate extracts (CE) obtained from autoclaved (100 and 121 °C) and extruded (90, 105, and 120 °C) black beans. After evaluation of the functional properties, the CE from autoclaved beans at 100 °C for 30 min and 121 °C for 15 min 2×, and extruded beans at 120 °C and 10 rpm, were selected to continue the remaining analysis. Autoclaving treatments at 100 °C for 30 min and 121 °C for 15 min 2× showed a reduction of resistant starch by 14.4% and 26.6%, respectively, compared to dehulled raw bean CE. Meanwhile, extrusion showed a reduction in resistant starch of 54.2%. Autoclaving and extrusion treatments also decreased the dietary fiber content. Extrusion reduced almost entirely the content of α-galactooligosaccharides, in comparison to dehulled raw bean CE. The results showed differences in color and granule morphology. The onset, peak, and conclusion temperatures, transition temperature range, and enthalpy of autoclaved and extruded bean CE were lower than dehulled raw bean CE. The CE from autoclaved and extruded beans contain retrograded and pregelatinized starch, which could be incorporated in food products as a thickening agent for puddings, sauces, creams, or dairy products. PRACTICAL APPLICATION: Thermally treated black bean carbohydrate extracts are rich in starch, fiber, and protein. Because these extracts are already cooked, they can be added to products that do not require a thermal process such as puddings, sauces, creams, or dairy products, acting as a thickening agent.

Study on rapid drying and spoilage prevention of potato pulp using solid-state fermentation with Aspergillus aculeatus

Effects of solid-state fermentation on rapid drying and spoilage prevention of potato pulp were evaluated. Pectin hydrolyzing and antibacterial ability of pectinase-secreting Aspergillus aculeatus and Bacillus subtilis were compared. A. aculeatus grew better in potato pulp, with highest pectinase yield of 342.71 ± 5.09 U/mL and rapid pH reduction to 3.76 ± 0.01. Next generation sequencing showed that the abundance of genera Candida and Enterobacter, which probably caused undesirable fermentation and spoilage, were significantly reduced after inoculation with A. aculeatus. In addition, fermentation with A. aculeatus significantly reduced water holding capacity from 16.63 ± 0.36 g/g to 7.78 ± 0.12 g/g, which resulted in lower viscosity and water binding capacity, and concomitantly significantly decreased moisture content from 76.05 ± 0.24% to 12.95 ± 0.19% after filtration and airflow drying. These results suggested that solid-state fermentation might be a promising technology for efficient processing and utilization of potato pulp.

Study on quality characteristics of cassava flour and cassava flour short biscuits

In this paper, the basic components, nutrient composition, and processing characteristics of cassava flour were determined. In addition, the effects of xanthan gum and inulin on the pasting properties, microstructure, and thermal properties of cassava flour were studied. Biscuits were prepared using cassava flour as the main raw material and the optimal technology and formula for the biscuits were determined by single-factor and orthogonal tests. The effects of xanthan gum and inulin on the quality of cassava flour short biscuits were also investigated, and volatile components in the biscuits were determined using electronic nose technique. The addition of xanthan gum improved the pasting properties and microstructure of cassava flour, and improved the taste and increased hardness and brittleness of the biscuits, making their quality similar to that of commercially available short biscuits. The addition of inulin inhibited the setback of starch and improved starch gelatinization. However, inulin was not suitable for processing of cassava flour biscuits as it decreased their hardness, brittleness, and taste. The optimal formula and baking conditions of cassava flour short biscuits were as follows: cassava flour 100 g, water 24 g, shortening 25 g, sugar 30 g, baking powder 0.6 g, salt 1 g, and egg 25 g; the surface fire and primer fire temperatures were 180°C, and the baking time was 9 min. In addition, although the main aroma volatile components present in cassava flour and low gluten wheat flour short biscuits were similar, the proportions of each component were different.