Observation and Measurement of Ice Morphology in Foods: A Review.

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.

Encapsulation of Concentrated Solution Obtained by Block Freeze Concentration in Calcium Alginate and Corn Starch Calcium Alginate Hydrogel Beads.

A model (sucrose and gallic acid) solution was concentrated by block freeze concentration (BFC) at three centrifugation cycles, and the solutions were encapsulated in calcium alginate and corn starch calcium alginate hydrogel beads. Static and dynamic tests determined the rheological behavior, differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) established thermal and structural properties, and the release kinetics was evaluated under in vitro simulated digestion experiment. The highest efficiency encapsulation value was close to 96%. As the concentrated solution increased in terms of solutes and gallic acid, the solutions were fitted to the Herschel-Bulkley model. Moreover, from the second cycle, the solutions exhibited the highest values of storage modulus (G') and loss modulus (G″), contributing to form a more stable encapsulation. The FTIR and DSC results demonstrated strong interactions between corn starch and alginate, establishing a good compatibility and stability in the bead formation. The kinetic release model under in vitro conditions was fitted to the Korsmeyer-Peppas model, demonstrating the significant stability of the model solutions inside the beads. Therefore, the present study proposes a clear and precise definition for the elaboration of liquid foods obtained by BFC and its incorporation inside an edible material that facilitates the controlled release in specific sites.

An approach on detection, quantification, technological properties, and trends market of A2 cow milk.

The genetic variant A2 ß-casein integrates the casein protein group in milk and has been often associated with positive health outcomes. Therefore, this review explores the present understanding of A2 ß-casein, including detection methods and the market trends for dairy from A2 milk. Also, the interaction of A2 ß-casein with αs1-casein and κ-casein genotypes was examined in terms of technological impacts on A2 milk. A limited number of preliminary studies has aimed to investigate the sensorial and technological impacts of ß-casein variants in milk matrices, for instance, in yogurt and other derivatives. Nevertheless, considering studies carried out so far, it is concluded that the manufacture of dairy products from A2 milk is perfectly feasible, as the products presented slight differences when compared to those derived from traditional milk. In one of the works, sensitive drops in rennet coagulation time and curd firmness values were observed in cheese traits. However, it is relevant to point out that variant A of κ-casein plays a negative role in the coagulation features of milk. Therefore, alterations in the pattern of cheese-making properties are not uniquely related to ß-casein variants. Attempts to produce A2 ß-casein in laboratory (non-natural source), through biosynthesis, for example, have not been found so far. This knowledge gap offers a promising area for future studies concerning proteins and bioactive peptide production.

Block freeze concentration by centrifugation and vacuum increases the content of lactose-free milk macronutrients.

Lactose-free milk is rising in popularity among consumers due to its claim to be a better digestible product compared to regular fluid milk. For that reason, concentrating on this food is a good alternative for increasing its versatility and usability in different dairy industry segments. Block freeze concentration (BFC) is a simple technology used to concentrate liquid foods through ice crystal formation and subsequent removal of water. Thus, this work aimed to test two variants of the BFC technique on lactose-free milk concentration. In the first approach, it was investigated the centrifugation-assisted BFC of skim lactose-free milk by applying a factorial experimental design. Temperature, time, and rotation speed were the factors, and the response variables included the concentrate yield, concentration index, and efficiency of the process. Concentrate yield and concentration index were mainly affected by the centrifugation temperature. On the other hand, individual factors did not have a significant effect on the efficiency, only their interactions. In the case of centrifugation-assisted BFC in a single step, the condition at 40°C, 70 min, and 4500 rpm was considered the best, given the highest values of efficiency and concentrate yield (80.87 and 67.02, respectively), and still an excellent value for concentration index (2.05). Conversely, the condition at 30°C, 45 min, and 3500 rpm was chosen to integrate a freeze concentration process in two stage. Then, the ice obtained from the first cycle was subjected to the vacuum-assisted BFC, which consisted in the second cycle. The concentrate obtained from the vacuum-assisted BFC presented contents of total solids, carbohydrates, and protein 2.95, 3.00, and 2.91 times more than the initial lactose-free milk, respectively. Therefore, we believe that the concentrates obtained can be used for the development of innovative lactose-free dairy products. PRACTICAL APPLICATION: Using concentration processes in the dairy industry can significantly contribute to enhancing the overall efficiency of milk processing since huge quantities of water from milk can be reduced, increasing the total solids content. In turn, dairy products that provide a high amount of solids (especially protein) are gaining in popularity among consumers, with consequent interest from researchers. In addition, milk concentration shows advantages in terms of processing, packaging, transportation, and handling. Since most changes occur in an aqueous environment, the removal of some parts of water results in the preservation of milk. It is noteworthy that dairy industries are concerned principally with food preservation, green technologies, and the production of high-quality products. Thus, concentration processes could favor the development of milk products rich in proteins to meet certain demands on functional and nutritional properties, for example in beverages and formulated food.

Effects of Cryoconcentrated Blueberry Juice as Functional Ingredient for Preparation of Commercial Confectionary Hydrogels.

Hydrogels can absorb and/or retain components in the interstitial spaces due to the 3D cross-linked polymer network, and thus, these matrices can be used in different engineering applications. This study focuses on the physicochemical and textural properties, as well as bioactive compounds and their antioxidant activity stability of commercial hydrogels fortified with cryoconcentrated blueberry juice (CBJ) stored for 35 days. CBJ was added to commercial hydrogels (gelatin gel (GG), aerated gelatin gel (AGG), gummy (GM), and aerated gummy (AGM)). The samples showed a total polyphenol, anthocyanin, and flavonoid content ranging from 230 to 250 mg GAE/100 g, 3.5 to 3.9 mg C3G/100 g, and 120 to 136 mg CEQ/100 g, respectively, and GG and GM showed the lowest bioactive component degradation rate, while AGM presented the highest degradation. GG and GM samples could be stored for up to 21 days without significant changes, while the results indicated ≈15 days for the AGG and AGM samples. Thereby, CBJ offers enormous possibilities to be used as a functional ingredient due to the high nutritional values, and it allows enriching different hydrogel samples, and in turn, the structures of hydrogels protected components during in vitro digestion, enhancing the bioaccessibility after the digestion process.

Optimization of Encapsulation by Ionic Gelation Technique of Cryoconcentrated Solution: A Response Surface Methodology and Evaluation of Physicochemical Characteristics Study.

The objective of this study was to evaluate the optimal conditions to encapsulate cryoconcentrate solutions via ionic gelation technique. Hydrogel beads were prepared using alginate (1%, 2% and 3% (w/w)) and cornstarch (0.5%, 1% and 2% (w/w)). Later, a sucrose/acid gallic solution was concentrated through block freeze concentration (BFC) at three cycles. Thus, each solution was a mixture with the respective combination of alginate/cornstarch. The final solution was added drop-wise on a CaCl2 solution, allowing the formation of calcium alginate-cornstarch hydrogel beads filled with sucrose/acid gallic solution or cryoconcentrated solution. The results showed that alginate at 2% (w/w) and cornstarch at 2% (w/w) had the best efficiency to encapsulate any solution, with values close to 63.3%, 90.2%, 97.7%, and 75.1%, and particle sizes of approximately 3.09, 2.82, 2.73, and 2.64 mm, for initial solution, cycle 1, cycle 2, and cycle 3, respectively. Moreover, all the samples presented spherical shape. Therefore, the appropriate content of alginate and cornstarch allows for increasing the amount of model cryoconcentrated solution inside of the hydrogel beads. Furthermore, the physicochemical and morphological characteristics of hydrogel beads can be focused for future food and/or pharmaceutical applications, utilizing juice or extract concentrated by BFC as the solution encapsulated.

Plant-Based Polyphenols: Anti-Helicobacter pylori Effect and Improvement of Gut Microbiota.

Helicobacter pylori (H. pylori) infection affects more than half of the world's population, and thus, about 10 to 20% of people with H. pylori suffer from peptic ulcers, which may ultimately lead to gastric cancer. The increase in antibiotic resistance and susceptibility has encouraged the search for new alternative therapies to eradicate this pathogen. Several plant species are essential sources of polyphenols, and these bioactive compounds have demonstrated health-promoting properties, such as the gut microbiota stimulation, inflammation reduction, and bactericidal effect. Therefore, this review aims to discuss the potential effect of plant-based polyphenols against H. pylori and their role in the gut microbiota improvement.

Blueberry juice: Bioactive compounds, health impact, and concentration technologies-A review.

Blueberries are a popular fruit with an attractive flavor and color, as well as health benefits. These health benefits have been attributed to the important number of bioactive compounds in blueberries with activities such as antioxidant, antitumor, antimutagenic, and antidiabetic effects and the prevention of cardiovascular diseases. Despite these advantages, blueberries are only obtained fresh in certain seasons; therefore, the food and beverage industry transforms them into jelly, puree, or juice. However, the concentration process could help preserve the bioactive compounds of blueberry byproducts. Concentration technologies focus on the removal of excess water to increase the product stability and reduce storage and transportation costs by causing them to take up less space or as a pretreatment before dehydration. These technologies include evaporation, reverse osmosis, and freeze concentration, and each one has different effects on the efficiency, quality, and nutritional value of the final concentrates. However, freeze concentration and reverse osmosis produce a higher-final quality concentrate than evaporation due to the use of low temperatures, which prevents the loss of thermolabile components such as bioactive compounds. Therefore, this review summarizes the impact of concentration technologies on the bioactive compounds and health benefits of blueberry juice.

Effect of Freeze Crystallization on Quality Properties of Two Endemic Patagonian Berries Juices: Murta (Ugni molinae) and Arrayan (Luma apiculata).

This work studied the effects of centrifugal block freeze crystallization (CBFC) on physicochemical parameters, total phenolic compound content (TPCC), antioxidant activity (AA), and process parameters applied to fresh murta and arrayan juices. In the last cycle, for fresh murta and arrayan juices, the total soluble solids (TSS) showed values close to 48 and 54 Brix, and TPCC exhibited values of approximately 20 and 66 mg gallic acid equivalents/100 grams dry matter (d.m.) for total polyphenol content, 13 and 25 mg cyanidin-3-glucoside equivalents/100 grams d.m. for total anthocyanin content, and 9 and 17 mg quercetin equivalents/100 grams d.m. for total flavonoid content, respectively. Moreover, the TPCC retention indicated values over 78% for murta juice, and 82% for arrayan juice. Similarly, the AA presented an increase over 2.1 times in relation to the correspondent initial AA value. Thus, the process parameters values were between 69% and 85% for efficiency, 70% and 88% for percentage of concentrate, and 0.72% and 0.88 (kg solutes/kg initial solutes) for solute yield. Therefore, this work provides insight about CBFC on valuable properties in fresh Patagonian berries juices, for future applications in health and industrial scale.

Comparative Study of the Structural Properties, Color, Bioactive Compounds Content and Antioxidant Capacity of Aerated Gelatin Gels Enriched with Cryoconcentrated Blueberry Juice during Storage.

Cryoconcentrated blueberry juice (CBJ) was incorporated into aerated gelatin gel and the effects on the mechanical properties, phenolic compounds and antioxidant activity (AA) were evaluated at day 1 and day 28 under refrigerated storage. At day 1, 8 g of gelatin gel and 40 g of CBJ (called M5) exhibited a soft texture and heterogeneous and non-spherical small bubbles, with values close to 10.5, 8.0 and 7.1 N, for hardness, gumminess and chewiness, respectively. M5 presented an increase of approximately 1.7, 1.9 and 1.9, and 1.2, 1.8, 2.1 and 1.3 times in comparison to the other samples, for total polyphenol, anthocyanin and flavonoid contents, and individual phenolic compounds, 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) assays, respectively. At day 28, the samples showed a weakening of the 3D network, with high degradation of phenolic compounds and AA due to the oxidation, polymerization and syneresis. Therefore, CBJ might be an interesting functional ingredient to add to (aerated and non-aerated) gelatin gel without affecting its properties, and thus different food products with high nutritional values and without added artificial sweeteners could be developed. Additionally, the gelatin gel/CBJ combinations might be suitable for additive manufacturing as a coating of food matrices.

Quality Attributes of Cryoconcentrated Calafate (Berberis microphylla) Juice during Refrigerated Storage.

This study aimed to evaluate the potential of centrifugal block cryoconcentration (CBCC) at three cycles applied to fresh calafate juice. The fresh juice and cryoconcentrate at each cycle were stored for five weeks at 4 °C and quality attributes were analyzed every 7 days. CBCC had significant effects in the calafate juice, since in the last cycle, the cryoconcentrate reached a high value of total soluble solids (TSS, ≈42 °Brix), with final attractive color, and an increase of approximately 2.5, 5.2, 5.1, 4.0 and 5.3 times in relation to the fresh juice values, for total bioactive compounds (TBC), 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC), respectively. However, at 35 days under storage, these values decreased by 5%, 13%, 15%, 19%, 24% and 27%, for TSS, TBC, DPPH, ABTS, FRAP and ORAC, respectively. Additionally, until the day 14, the panelists indicated a good acceptability of the reconstituted cryoconcentrate. Therefore, CBCC can be considered a novel and viable technology for the preservation of quality attributes from fresh calafate juice with interesting food applications of the cryoconcentrates due to their high stability during storage time in comparison to the fresh juice.

Protection of polyphenols in blueberry juice by vacuum-assisted block freeze concentration.

Block freeze concentration allows produces high-quality cryoconcentrates with important protection of valuable components from fresh fruit juices. The aim of this study was to investigate the use of vacuum-assisted block freeze concentration under different experimental conditions to protect polyphenols in the elaboration of concentrated blueberry juice. Fresh blueberry juice was radial or unidirectional frozen at -20 and -80 °C for 12 h and vacuum process was performed at 80 kPa during 120 min. Results showed a significant solute increased in the concentrated fraction in all treatments, and the best treatment was - 20 °C/unidirectional with a value of ≈63 °Brix, equivalent to an increase of 3.8 times in the total polyphenol content (76% of retention). The color of concentrated samples was darker than the initial sample, with ΔE* values of >25 CIELab units in all treatments. The vacuum-assisted block freeze concentrations was an effective technology for protecting polyphenols and obtain a concentrated with a higher concentration of solids from blueberry juice, as well as interesting values of process parameters.