Rheology and fluid dynamics properties of sugarcane juice

Plant-based hydrocolloids for efficient clarification of cane juices: rheological analysis and solidification studies

The present study is designed to study the efficiency of plant-based hydrocolloids for the efficient clarification of sugarcane juice and subsequent production of non-centrifugal sugars (NCSs). NCSs are generally produced with lime or other inorganic solids as a clarification agent, often leading to products with a bland taste and dark color. This work is a first of its kind, where plant-based hydrocolloids such as starch, xanthan gum, and guar gum are used for clarification studies. Clarification efficiency was evaluated in terms of separation efficiency, turbidity removal, sucrose content, color transmittance, and rheology studies. Preliminary studies revealed that starch showed a better separation efficiency of 78% compared to other hydrocolloids, and further rheology studies of starch-clarified juice showed a favourable shear-thickening (dilatant, n = 1.382) behaviour, whereas the other two hydrocolloids showed an unfavourable shear-thinning (pseudo plastic, n < 0.9) behaviour. Eventually, starch was found to be a better clarification agent and is proposed as an alternative to lime-based clarification. Solidification studies were performed with starch at various concentrations (0.02-0.04%), pH (6.8-7.2), and temperature (80 °C-100 °C), and it was found that NCSs produced via starch clarification showed superior properties compared with traditional lime-based clarification processes.

Ultrasound-assisted acid hydrolysis of cassava (Manihot esculenta) bagasse: Kinetics, acoustic field and structural effects

Improving the actual acid hydrolysis of cassava bagasse (CB) with the assistance of high-intensity ultrasound (US) was aimed in comparison with mechanical agitation (AG). The kinetics of reducing and total sugar release were mathematically modeled. The acoustic field characterization and apparent viscosity of the suspensions were correlated. Moreover, microscopic analyses (visible, fluorescence and polarized light) were carried out to identify changes produced by the treatments. Both AG and US-treatments showed themselves to be effective at hydrolyzing CB. However, US-experiments reached equilibrium in the reducing sugar release process earlier and obtained slightly higher values of total sugars released. The Naik model fitted the experimental data with good accuracy. A greater loss in the birefringence of the starch granules and the degradation of lignocellulosic matter was also observed in US-assisted hydrolysis. The actual acoustic power applied was reduced after hydrolysis, probably due to the increase in the apparent viscosity of the resulting suspensions.

Sugarcane Juice with Co-encapsulated Bifidobacterium animalis subsp. lactis BLC1 and Proanthocyanidin-Rich Cinnamon Extract

Bioactive compounds are sensitive to many factors, and they can alter the sensory characteristics of foods. Microencapsulation could be a tool to provide protection and allow the addition of bioactives in new matrices, such as sugarcane juice. This study focused on producing and evaluating the potential function of probiotics and proanthocyanidin-rich cinnamon extract (PRCE), both in free and encapsulated forms when added to sugarcane juice. The pure sugarcane juice treatment T1 was compared with other sugarcane juices to which bioactive compounds had been added; T2, a non-encapsulated Bifidobacterium animalis subsp. lactis (BLC1); T3, a non-encapsulated BLC1 and PRCE; T4, BLC1 microcapsules; and T5, with BLC1 and PRCE microcapsules. The samples were morphologically, physicochemically, rheologically, and sensorially characterized. Samples were also evaluated regarding the viability of BLC1 during the juice's storage at 4 °C. It was possible to produce probiotic sugarcane juice with non-encapsulated BLC1, but not with the addition of free PRCE, which in its free form reduced the viability of this microorganism to < 1 log CFU/mL after 7 days. The microcapsules were effective to protect BLC1 during juice storage and to maintain high contents of phenolic and proanthocyanidin compounds, although the products containing these had their viscosity altered and were less accepted than either the control or those with non-encapsulated BLC1.

Magnetic chitosan-hydroxyapatite composite microspheres: Preparation, characterization, and application for the adsorption of phenolic substances

The phenolic substances in sugarcane juice seriously affect the color value of sugar products, and gallic acid is one of the main phenolic substances. To develop a new adsorbent able to effectively adsorb phenolic substances from sugarcane juice, magnetic chitosan (CS) hydroxyapatite (HA) microspheres (MCHAM) were prepared by growing HA on magnetic CS microspheres (MCM) in-situ. MCHAM could effectively adsorb gallic acid from sucrose solution, and the highest adsorption capacity was 40.77 mg g^-1. The adsorption kinetics indicated that the adsorption process fit the pseudo-second-order mode, the dominant mechanism was chemisorption, and the Langmuir isotherm mode (q_m = 48.12 mg g^-1) described the adsorption behavior of MCHAM best. Recycling experiments indicated that the MCHAM adsorbent presented considerable repeatability. Compared to treating phenolic substances in sugarcane juice using traditional clarifying agents, treatment methods employing MCHAM can efficiently and simply remove phenolic substances without leaving residual sulfur in sugarcane juice.

The flow properties of honey-malt spread

In this study, the effect of barley malt extract at two brix levels (74 and 79 °Bx) and three ratios of malt extract/honey (65:35, 70:30 and 75:25) on the flow behavior properties of honey-malt spread at three temperature levels (35 ℃, 45 ℃ and 55 ℃) was investigated. Time-dependent behavior data of the spread samples were appropriately fitted to the Weltman, first-order stress decay with a zero stress value and first-order stress decay with a non-zero stress value models. Also, the Power-law, Herschel-Bulkley, Casson and Bingham models were used for curve fitting the time-independent behavior data. Regarding the R² and root mean square error coefficients, the first-order stress decay with a non-zero stress value and Herschel-Bulkley models were selected as the suitable models to describe the flow behavior of samples. The results for time-dependent properties showed that spread samples exhibit a thixotropic behaviour, as the viscosity for all samples decreased with increase in shearing time at a constant shear rate of 50 s^-1.

Physical Properties of Red Guava (Psidium guajava L.) Pulp as Affected by Soluble Solids Content and Temperature

Physical properties of fluid and semisolid foods, such as density and rheological behavior, must be carefully taken into account on designing unit operations for the processing of such kind of products. In this work, a rotational rheometer of concentric cylinders was used to evaluate the rheological behavior of red guava pulp (Psidium guajava L.), with different soluble solids content (5, 10, and 15°Brix), at four temperatures (10, 30, 50, and 70°C). Also density data were obtained using pycnometry. Models were fitted to the obtained experimental data, in order to mathematically represent the rheological parameters and the density as functions of temperature and soluble solids content. The rheological behavior of the red guava pulp was adequately described by the Ostwald-de-Waele model, with a pseudoplastic behavior. Models to describe the simultaneous effect of temperature and concentration on the density were also presented.

Thermophysical and rheological properties of dulce de leche with and without coconut flakes as a function of temperature

Dulce de leche (DL), a dairy dessert highly appreciated in Brazil, is a concentrated product containing about 70% m/m of total solids. Thermophysical and rheological properties of two industrial Brazilian Dulce de leche formulations (classic Dulce de leche and Dulce de leche added with coconut flakes 1.5% m/m) were determined at temperatures comprised between 28.4 and 76.4 °C. In general, no significant differences (p < 0.05) were observed in the presence of coconut flakes in the two formulations. Heat capacity varied from 2633.2 to 3101.8 J/kg.°C; thermal conductivity from 0.383 to 0.452 W/m.°C; specific mass from 1350.7 to 1310.7 kg/m³; and, thermal diffusivity from (1.082 × 10-7 to 1.130 × 10-7) m²/s. The Bingham model was used to properly describe the non-Newtonian behavior of both formulations, with yielding stress values varying from 27.3 to 17.6 Pa and plastic viscosity from 19.9 to 5.9 Pa.s.