A comparative study of black mulberry juice concentrates by thermal evaporation and osmotic distillation as influenced by storage

Free and glycosidically bound aroma compounds in fruit: biosynthesis, transformation, and practical control

Fruit aroma makes an initial flavor impression and largely determines the consumer preference and acceptance of fruit products. Free volatile organic compounds (FVOCs) directly make up the characteristic aromas of fruits. While glycosidically bound volatile compounds (GBVs) can be hydrolyzed during fruit ripening, postharvest storage, and processing, releasing the attached aglycones as free volatiles that could alter the overall aroma attributes of fruits. GBVs typically exhibit significantly higher concentrations than their free counterparts in fruits such as grapes, cherries, kiwifruits, tomatoes, and tamarillos. This review highlights the biosynthesis of FVOCs and GBVs in fruit and illustrates their biological transformations for various functional purposes such as detoxification, aroma enhancement, plant defense, and pollinator attraction. Practical applications for regulating the levels of aroma compounds emitted or accumulated in fruit are also reviewed, emphasizing the metabolic engineering of free volatile metabolites and hydrolytic technologies on aroma glycosides. Generally, enzymatic hydrolysis using AR2000 is a common strategy to enhance the sensory attributes of fruit juices/wines, while acidic hydrolysis induces the oxidation and rearrangement of aglycones, generating artifacts with off-aromas. This review associates the occurrence of free and glycosidic bound volatiles in fruit and addresses their importance in fruit flavor enhancement and industrial applications.

Membrane techniques in the production of beverages

The most important developments in membrane techniques used in the beverage industry are discussed. Particular emphasis is placed on the production of fruit and vegetable juices and nonalcoholic drinks, including beer and wine. This choice was dictated by the observed consumer trends, who increasingly appreciate healthy food and its taste qualities.

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.

Variations in Anthocyanin Profiles and Antioxidant Activity of 12 Genotypes of Mulberry (Morus spp.) Fruits and Their Changes during Processing

Mulberry fruits are known as rich sources of anthocyanins and are consumed in syrup form after the addition of sugar and acid; however, there is little information on the anthocyanin composition and antioxidant activity of mulberries of different cultivars and their changes during processing. To address this, the antioxidant activity and anthocyanin composition of 12 cultivar mulberry fruit cultivars were investigated by high-performance liquid chromatography and ultra-high-performance liquid chromatography coupled with electrospray ionization/quadrupole time-of-flight. Additionally, different quantities of citric acid were used to evaluate antioxidant activities and anthocyanin composition of mulberry syrup. Sixteen anthocyanins were identified in mulberry fruits using accurate mass spectrometry. Several anthocyanins were tentatively identified for the first time in mulberry fruits and include: malvidin hexoside, cyanidin malonyl hexose hexoside, cyanidin pentoside, cyanidin malonyl hexoside, petunidin deoxyhexose hexoside, and cyanidin deoxyhexoside. The major anthocyanin in mulberries was cyanidin-3-O-glucoside, followed by cyanidin-3-O-rutinoside. Morus Alba L. Iksu showed the highest cyanidin-3-O-glucoside content (8.65 mg/g dry weight) among 12 mulberry fruit cultivars. As citric acid levels increased, mulberry syrup showed significantly higher antioxidant activity (p < 0.05).

Membrane-Based Operations in the Fruit Juice Processing Industry: A Review

The fruit juice industry is one of the food sectors that has invested the most in the implementation of new technologies, such as non-thermal technologies. Among them, membrane processes are considered today well-established separation techniques to support the production and marketing of innovative fruit juices designed to exploit the sensory characteristics and nutritional peculiarities of fresh fruits. Pressure-driven membrane operations, membrane distillation, osmotic distillation and pervaporation have been widely investigated in the last few decades to replace conventional technologies used in fruit juice processing industry (i.e., clarification, stabilization, concentration and recovery of aroma compounds). This paper will review the significant progresses on the use of membrane-based operations in fruit juice processing industry in the light of the growing interest towards products with improved safety, quality and nutritional value and sustainable processes characterized by low energy consumption and low environmental impact.

Heat Transfer Performance of Vertical Tube Falling Film Juice Evaporator and a Sensitivity Analysis

Fresh fruit juice has a short storage period and it usually needs to be concentrated for shelf-life extension. Evaporation of fruit juice is an attractive method and vertical tube falling film evaporator is one of good choice. The main problem in the design of the evaporator is the reliable estimation of the heat transfer coefficient for all effects. In this paper, the effects of feed flow rate, evaporation temperature, temperature difference, and juice soluble solid content on heat transfer coefficient of a vertical falling film evaporator were investigated. The Bayesian treed Gaussian process model was used to identify the key variables affecting the heat transfer coefficient, which showed that evaporation temperature had the greatest influence on the sensitivity of heat transfer coefficient. It also demonstrated that complex interactions existed between the four operating parameters had a significant effect on the overall heat transfer coefficient.

A Comparative Study of the Effects of Ultrafiltration Membranes and Storage on Phytochemical and Color Properties of Mulberry Juice

We investigated the influence of both the clarification by ultrafiltration membranes with 100 or 18 kDa molar weight cut-off (MWCO) and subsequent storage on phenolic properties and color of mulberry juice (MJ). Results showed that clarification by the ultrafiltration membrane with 100 kDa MWCO elevated levels of total polyphenols (↑11.4%), total monomeric anthocyanins (↑87.7%), phenolic acids and flavonoids (↑10-64%), thus leading to enhanced antioxidant activity (↑twofolds) and α-glucosidase inhibitory rate (↑23.3%), as well as redness (↑37.9%), which were sharply decreased in the clarified MJ by the ultrafiltration membrane with 18 kDa MWCO. MJ pretreated by the membrane with 100 kDa MWCO exhibited better storage stability than the other two juices. Hence, the ultrafiltration membrane with 100 kDa MWCO has great potential in juice clarification for purpose of enrichment of phenolic compounds, and enhancement of bioactive activities and storage stability. PRACTICAL APPLICATION: Mulberry juice has many health benefits related to phenolic compounds. Clarification is necessary to obtain a bright, clear juice and improves juice taste, thus making a favorable first impression on consumer. Ultrafiltration membrane with 100 kDa MWCO is recommended in mulberry juice processing, since it helps to enrich phenolic compounds, and enhance bioactive activities and sensory quality of mulberry juice.

Simulation of mass transfer in hollow fiber used for concentration of juices by osmotic distillation

A bi-dimensional diffusion mathematical model is proposed to study mass transfer in hollow fiber used for the concentration of juices by osmotic distillation (OD). The mathematical model was solved using the Finite Volume Method (FVM). The mass fraction at the boundaries was calculated by using the Functional-group Activity Coefficients (UNIFAC) method for the juice and by the Analytical Solutions Of Groups (ASOG) method for the brine. Calculated results were compared to an analytical solution for a case of mass diffusion in a cylinder with mass flow boundary condition. An algorithm to find the effective diffusion coefficient of gas through the membrane is proposed. To show its usefulness, different velocities were applied over the fiber surface to study the bi-dimensional effects that this velocity field has on the mass transfer inside the fiber. The results showed a maximum error of 5.6% when compared to experimental results.

Influence of fruit juice processing on anthocyanin stability

Anthocyanins are quality determining compounds in red fruits and their corresponding juices. The fate of anthocyanins during production of juices is determined by countless factors and all of these need to be taken into consideration to optimize juice processes. Storage and pre-press procedures like freezing and thawing may influence the fruit's integrity and accordingly affects the extraction of valuable components during the subsequent mashing and pressing. Conventional thermal or novel non-thermal treatments to ensure microbial safety have both positive and negative effects on the anthocyanins. By inactivation of oxidizing enzymes, profiles and quantities of anthocyanins may be maintained, but more severe conditions may have adverse effects. To improve juice extraction and to increase yield, enzyme-assisted degradation of the cell walls is conducted. The applied enzyme preparations contain numerous side activities which also may degrade anthocyanins. Clarification and concentration will further reduce the final anthocyanin concentrations. Many studies have been published regarding evaluating individual fruits or single processing steps but, obviously, these results are not necessarily transferable. Accordingly, this review aims to summarize all relating studies comprehensively to the fate of anthocyanins during juice processing giving an overview of underlying mechanisms as well as the chemical and analytical background.