Eduardo Hernández

The aim of this work is the cryoconcentration of olive mill wastewater (OMW) to produce highly concentrated polyphenols solutions that can be applied in the tanning industry. The treatment by cryoconcentration consists of four steps: cooling, freezing, sweating, and melting. The operation purifies the ice in depth by partially melting the impure zones trapped in the pockets of concentrated solutions formed in the ice. Cryoconcentration yields five types of fractions liquid solutions with different concentrations of organic and mineral matter: two highly concentrated solutions compared to the raw OMW, a solution with a similar concentration to the initial one, and two purified solutions with significantly lower concentrations than the initial solution. In three cycles, the technique increased the concentration of total phenols from 22.9 to 103.2 g L⁻¹. The cryoconcentrated solutions have been applied to tanning hides in static mode without stirring and in rotary mode. The study revealed the significant impact of the polyphenolic compounds concentration in cryoconcentrated OMW and the duration of tanning on the rise in the shrinkage temperature of the leather product. The shrinkage temperature of leather tanned with cryoconcentrated OMW is between 75 °C and 80 °C. Tanning with cryoconcentrated OMW produces leathers having good mechanical properties (tear strength, tensile strength, and elongation) and a darker color than that of mimosa- and chestnut-tanned leathers. Finally, cryoconcentrated OMW can be considered a new source of tannins for the ecological tanning of leather, which is aligned with the Sustainable Development Goals (SDG) adopted by the United Nations for the management of natural resources and the reduction of environmental impact, through the valorization of waste and by-products.

The development of functional dairy products has increasingly become a focus of the dairy industry, with goat milk gaining prominence due to its nutritional properties and digestibility. This study aimed to evaluate the effects of freeze concentration processes on skimmed goat milk, observing its potential prebiotic effects and impacts on the physical, chemical, microbiological, rheological, and sensory profiles of fermented milk, using the Preferred Attributes Elicitation (PAE) methodology. Skimmed goat milk was initially concentrated using the gravitational block freeze concentration technique. A fermented milk containing probiotics (FM1) was produced from this concentrate. In addition, two other samples were developed: one with skimmed goat’s milk, 6% inulin, and probiotics (FM2) and another using whole goat’s milk with probiotics as a control (FM3). The results indicated that the freezing concentration process resulted in a concentrate with 14.70 ± 0.06 g 100 g⁻¹ of total solids. Among the three types of fermented milk, FM1 presented the highest values of total solids and titratable acidity. Regarding color, both FM1 and FM2 tended towards yellowish and greenish tones, while FM3 presented a greater luminosity. During storage, all fermented milks maintained their probiotic properties. The freeze concentration process increased the viscosity of FM1, a characteristic also evidenced in the sensory evaluations using PAE. In contrast, FM2 presented a rheological behavior similar to that of the control (FM3). Regarding sensory acceptance, FM1 had lower acceptance regarding aroma, being described as having notes of “goat flavor” and “acid” and being “salty”. The PAE methodology proved effective in characterizing the sensory qualities of the products, providing valuable information for developing new dairy products. These results offer an important theoretical basis for the industrial production of functional dairy products based on goat’s milk, helping to evaluate quality characteristics and optimize manufacturing processes.

Freeze concentration (FC), a low‐cost alternative technology to separate and concentrate high‐value compounds, was applied to three distinct craft ale beer styles—Witbier, Bitter, and Porter—to investigate its impact on vital beer statistics. A central composite design with freezing temperature and ice fraction as factors was employed, with response surface analysis revealing significant effects on the average ice growth rate (), concentration index (CI), and average distribution coefficient () of ethanol, total solids, color, and bitterness in the liquid fraction. Results showed that ice fraction primarily influenced solute concentrations and increased with ice fraction due to water removal. Freezing temperature affected . The type of beer had a significant impact on color and bitterness, reflecting the specific style parameters. Furthermore, response optimization yielded conditions that significantly altered beer statistics, leading to changes in ethanol content, total solids, color, and bitterness, possibly classifying them as new beer styles. The study demonstrates the potential of FC to influence the beer characteristics and broaden the range of beer styles.Practical applications: Innovations in science and technology, added to the search for new beer styles, promote the development of new products in the beer industry. In this article, a potential use of the freeze concentration technology was identified for the development of new concentrated beer products. The impact of progressive stirred freeze concentration in three craft beers was studied. First, obtaining a concentrated beer from this technique was possible, with a higher concentration of total solids and ethanol. In addition, the vital statistics of beer could be modified using freeze concentration to obtain novel concentrated beer products.

Freezing is an effective technology with which to maintain food quality. However, the formation of ice crystals during this process can cause damage to the cellular structure, leading to food deterioration. A good understanding of the relationship between food microstructure and ice morphology, as well as the ability to effectively measure and control ice crystals, is very useful to achieve high-quality frozen foods. Hence, a brief discussion is presented on the fundamentals/principles of optical microscopic techniques (light microscopy), electronic microscopic techniques (transmission electron microscopy (TEM) and scanning electron microscopy (SEM)), as well as other non-invasive techniques (X-rays, spectroscopy, and magnetic resonance) and their application to measuring ice formation rates and characterizing ice crystals, providing insight into the freezing mechanisms as well as direct monitoring of the entire process. And, in addition, this review compares (the negative and positive aspects of) the use of simple and cheap but destructive technologies (optical microscopy) with detailed microscopic technologies at the micro/nanometer scale but with pretreatments that alter the original sample (SEM and TEM), and non-destructive technologies that do not require sample preparation but which have high acquisition and operational costs. Also included are images and examples which demonstrate how useful an analysis using these techniques can be.

The scientific importance involved in this study was the use of whey, a co-product of the cheese industry, and its performance during the freeze concentration process. Moreover, the best-concentrated whey from the freeze concentration process, about the total solids, proteins, and mineral contents, was used to prepare two functional fermented lactic beverages. Therefore, whey was subjected to the freeze concentration in blocks with gravitational thawing. Process performance indicated better yields and efficiency for the second stage of freeze concentration. Concentrated whey 2 was used to prepare two fermented lactic beverages added with probiotics: one without adding guabiroba pulp (control) and a beverage incorporated with 10% guabiroba pulp. Containing guabiroba pulp was not enough to modify the total solids, proteins, and mineral contents. However, it decreased pH values, changed the color to an orange hue, and decreased luminosity. The fermented lactic beverage added with probiotic and 10% guabiroba pulp showed 1.61× more phenolic compounds and an increase of 164% for each evaluated carotenoid content compared with the control beverage.

Block cryoconcentration is a technique that can be applied to obtain fruit juice concentrates while preserving their nutritional, bioactive and organoleptic properties. Until now, the investigations present both the centrifugation and vacuum cryoconcentration method independently for different matrices, but with different purposes such as observing the effect of the initial freezing temperature, the freezing direction, whether radial or unidirectional, the effect of several cycles of cryoconcentration, comparing cryoconcentration with other concentration methods, etc. However, there is no study that compares both methods in the same matrix considering some common parameters such as cryoconcentration time. The objective of this research work was to compare two block centrifugation methods, centrifugation‐assisted (CABC) and vacuum‐assisted (VABC). A factorial experimental design was used. The operation conditions evaluated were 110 RCF and 2360 RCF, and 10 and 70 kPa at the same time conditions (4 and 12 min). Pomegranate juice was frozen at −20°C unidirectionally for 48 h before treatments. For the response studied—concentration index (CI), solute yield (SY, %) and efficiency (Eff, %)—CABC at 110 RCF for 12 min showed the best overall results (SY = 59.2% and Eff = 84.3%) and the desirability was .91. For VABC at 10 kPa for 12 min, the desirability was .98 but SY was lower. In both methods, the CI in one cycle was up to 3.0. The advantage of both systems is that in one cycle the CI, SY and Eff were higher than those obtained by other investigations on pomegranate juice.Practical applications: Cryoconcentration is an emerging technology for concentrating a food solute in a solution based on the separation of ice crystals from a freeze‐concentrated solution. The nutritional and sensory quality of cryoconcentrated fruit juices is higher than those concentrated conventionally by means of evaporation due to the low processing temperatures. Consumer demand for food rich in bioactive components for a healthy lifestyle is growing. With the use of the block freeze concentration technique, it is possible to produce a pomegranate juice concentrate with excellent nutritional properties. Two techniques for assisted block cryoconcentration of pomegranate juice—vacuum and centrifugal—were compared in a single cycle. Both methods showed better performance in once cycle than other cryoconcentration methods at lab scale. The generated knowledge in this study can be easily adapted for the juice industry in order to improve the process parameters of block freeze concentration in the elaboration of concentrated pomegranate juice.