Effects of heating method and conditions on the evaporation rate and quality attributes of black mulberry (Morus nigra) juice concentrate

Microwave heating concentration of raspberry pulp: Evaluation of processing variables on concentration characteristics and quality attributes

Concentration of fruit pulp is an important unit operation in food processing and has a wide range of applications. In this study, the microwave heating concentration (MHC) of raspberry pulp at different microwave powers, heating times and sample masses were investigated considering concentration characteristics and quality attributes. The results showed that increasing microwave power/heating time or decreasing sample mass significantly decreased the moisture content but had no significant effect on the temperature of raspberry pulp, while these conditions resulted in loss of total anthocyanin content and deterioration of total color difference. LF-NMR and SEM results revealed that the changes in temperature and moisture content caused by MHC significantly affected the total anthocyanin content and total color difference of the final product. Microwave power of 800 W, heating time of 3 min and sample mass of 90 g are selected as suitable parameters for MHC of raspberry pulp. This study may provide guidance for the development of appropriate technology for MHC of berry pulp.

Lactic acid bacteria as an adjunct starter culture in the development of metabiotic functional turmeric (Curcuma longa Linn.) beverage

Turmeric (Curcuma longa) is a highly nutritious rhizomatous herbaceous plant with remarkable chemical composition and biologically active compounds. This study aimed to evaluate the turmeric, ginger and lemon blend as a fermentable substrate by lactic acid bacteria to develop a fermented nondairy beverage. Results showed that turmeric blend (turmeric 2%w/v, ginger 1.5% v/v, 5% v/v) was an excellent matrix for lactic acid bacteria growth and fermentation dramatically increased total phenolic, flavonoid content and antioxidants capacities impacting the color and sensory properties. Moreover, the formulated fermented turmeric blend was stable for more than 90 days at 4°C with a healthy bacterial population and nutraceutical stability. Turmeric beverage also inhibited the growth of Caco-2 and MOLT 4 cancerous cell lines in a dosage and time-reliant manner. This way, lactic acid fermentation can be considered as an appropriate tool for developing turmeric based novel bio-intervention with enhanced bioactivity and antagonistic efficacy against recurring food-borne pathogen in this post-antibiotic era.

Quality Evaluation of Lemon Cordial Stored at Different Times with Microwave Heating (Pasteurization)

Consumer interest in food quality and safety has shifted over time, as consumers increasingly prefer minimally processed items. As a result, numerous non-thermal approaches have been implemented due to their potential to preserve the nutritional profile of products along with lengthening their storability. Microwaving, a green processing technique, volumetrically heats the product because of the interactions developed between charged ions, polar water molecules of foodstuff and the incoming electromagnetic waves. The study was mapped out to investigate the effect of microwave exposure time (60, 90 and 120 s) at fixed power (1000 W) and frequency (2450 MHz) on physicochemical properties, phytochemical constituents, antioxidant potential and microbial counts of lemon cordial stored at refrigerated temperature (4 ± 2 °C). The mentioned parameters were analyzed after an interval of 30–90 days. Statistical findings illustrated a highly significant (p ≤ 0.01) impact of microwave treatment and storage on titratable acidity, pH, total soluble solids, total phenolic contents, total flavonoids contents, antioxidant potential and total plate count. Sample microwaved for 120 s showed the highest pH values (2.45 ± 0.050), total soluble solids (56.68 ± 2.612 °B) and antioxidant activity (1212.03 ± 716.5 µg—equivalent of ascorbic acid per 100 mL of cordial); meanwhile, it exhibited the lowest total plate counts (1.75 ± 0.144 Log 10 CFU/mL). Therefore, microwaving can be suggested as a suitable alternate to traditional pasteurization techniques as well as to chemical preservatives.

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.

Physicochemical changes of barberry juice concentrated by liquid desiccant-assisted solar system and conventional methods during the evaporation process

The preservation of the quality characteristics of fruit juices during the processing is one of the major challenges in the fruit juice industries. The high costs of fossil fuels and their environmental pollution increased the need to use of the renewable energies. In the present study, some quality characteristics of barberry juice were investigated during concentrating by the methods of liquid desiccant-assisted solar juice concentration system (LD-ASJCS) at the air flow rates of 0.006-0.014 kg/s, rotary vacuum evaporation system (RVES), and evaporation at atmospheric pressure (EAP). Although evaporation rate in LD-ASJCS increased by 25% with increasing of air flow rate from 0.006 to 0.014 kg/s, but it had negative effects on some quality properties of concentrated juices. The anthocyanins retention in the concentrated juices with different air flow rates of LD-ASJCS method were 16-28%. Reduction of the air flow rate resulted in a lower browning index and less variation of color indices (L*, a*, and b*). The a* values, browning index, and sensory attributes of the concentrated juices in the LD-ASJCS at the air flow rate of 0.006 kg/s were comparable to the concentrated juices by the RVES method. Although, RVES method compared to EAP and LD-ASJCS methods better improved the quality of barberry juice, but the LD-ASJCS method can be considered in fruit juice industries because of maintaining quality and sensory attributes, saving energy, and reducing environmental pollution. The mathematical modelling of physicochemical changes of LD-ASJCS concentrated juice showed that these variations are fitted with first-order and zero-order models.

Production of grape pekmez by Ohmic heating-assisted vacuum evaporation

Pekmez is a concentrated syrup-like food conventionally produced by vacuum evaporation process from sugar-rich fruits. In this study, the applicability of grape pekmez production by ohmic heating assisted vacuum evaporation (ΩVE) method was investigated. Conventional vacuum evaporation (CVE) and ΩVE methods were compared in terms of physicochemical properties, HMF (5-hydroxymethylfurfural) contents, rheological properties, and energy consumptions. ΩVE was run at four different voltage gradients (17.5, 20, 22.5, and 25 V/cm). Total process times for grape pekmez production were determined as 57, 28.5, 32, 39, and 50 minutes for CVE, ΩVE (25 V/cm), ΩVE (22.5 V/cm), ΩVE (20 V/cm) and ΩVE (17.5 V/cm), respectively. Energy consumption of CVE method was higher than ΩVE method for all voltage gradients. Energy efficiency increased as the voltage gradient increased. There was no significant difference between CVE and ΩVE methods for HMF contents. The results show that the ΩVE method could be an alternative to the CVE process for grape pekmez production.

Buffalo cheese whey hydrolyzed with Alcalase as an antibrowning agent in minimally processed apple

Buffalo whey was hydrolyzed with Alcalase for different times t_i (i = 0, 0.5, 1, 2, 3, 4 or 6 h) and the browning inhibition of minimally processed apples was investigated. The hydrolysis process was followed by determination of the degree of hydrolysis. In order to understand possible modes of action on the enzymatic browning, whey was submitted to the analysis of antioxidant activity (ABTS^·+ radical sequestration, Fe²⁺ chelating activity and reducing power), reactivity with quinones and inhibitory activity on polyphenol oxidases (PPO) extracted from Red Delicious apples. Buffalo whey showed significant increase in degree of hydrolysis, antioxidant activity, reactivity with quinones and PPO-inhibitory activity as a function of the hydrolysis time. Maximum PPO-inhibitory activity was observed from 4 h hydrolysis (t_4h hydrolysate), reaching about 50% inhibition. Then, slices of minimally processed apples were immersed in a buffered solution of the t_4h hydrolysate, packed and subjected to instrumental color evaluation during storage for up to 6 days. As for the ability to inhibit the browning of the minimally processed apples, the hydrolyzate kept the L∗ parameter of the apples during 6 days of storage, not statistically differing from the metabisulfite. In addition to the luminosity, the hydrolyzed whey was able to maintain the browning index of the apples at lower values during this storage time compared to the non-hydrolyzed whey. These results evidence possible applications of buffalo whey hydrolyzed with Alcalase as a natural substitute for additives conventionally used in the control of enzymatic browning in foods.

Effect of lactobacillus strains on phenolic profile, color attributes and antioxidant activities of lactic-acid-fermented mulberry juice

This study was conducted to investigate the effect of lactic acid bacteria (LAB) strains on color properties, phenolic profile and antioxidant activities of mulberry juice. Mulberry juice was separately fermented at 37 °C for 36 h using Lactobacillus plantarum, Lactobacillus acidophilus and Lactobacillus paracasei. The results showed that lactic acid fermentation impacted on the color of the juice. Moreover, the study demonstrated that LABs impacted on the phenolic profile of the juice. Syringic acid, cyanidin-3-O-rutinoside and quercetin were the predominant phenolic acid, anthocyanin and flavonol respectively in the lactic-acid-fermented mulberry juice. The degree of radical scavenging activity was species-specific with the L. plantarum fermented juice having the highest radical scavenging activities. The correlation analysis demonstrated that flavonols and anthocyanins were mostly responsible for the increased in 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) scavenging activity while phenolic acids and flavonols were responsible for 2,2-diphenyl-1-picrylhydrazyl scavenging activity and reducing power capacity of the fermented juice.

Effects of concentration method and storage time on some bioactive compounds and color of jujube (Ziziphus jujuba var vulgaris) concentrate

Jujube extract was concentrated by various heating methods including vacuum, microwave and conventional heating. The effect of concentration methods and storage time (for 90 days at 4 °C) on total phenolic and total monomeric anthocyanin contents, individual anthocyanins, individual organic acids, and color values of jujube concentrate was investigated separately. The desired level of concentration (65.0 °Brix) was achieved in 45, 96 and 117 min by the microwave, vacuum and conventional heating methods, respectively. The concentrate obtained with microwave method had the highest total phenolic content (159.32 mg GAE/g DW) and total monomeric anthocyanin content (48.84 mg cyn-3-glu/100 g DW) in comparison to the other methods at the beginning of storage. Hunter color parameters (L*, a* and b*) decreased significantly with increasing the time of storage in all cases; however, this effect was more obvious in the vacuum heating. Cyanidin-3,5-diglucoside was determined as the major anthocyanin in all concentrates, while its degradation was more pronounced in the conventional heating (25.59%) comparing to the microwave (11.14%) and vacuum methods (17.59%) during the 90-day storage. The jujube concentrate prepared with the microwave method had the highest organic acid contents (e.g. malic, citric, succinic and ascorbic acids) as compared to the other methods. Thus, according to the results, the heating method and storage time had significant effects on the bioactive compounds and color values of jujube concentrate. In general, microwave energy could be successfully used in production of jujube concentrate followed by 90-day storage.

Influence of Black Mulberry Juice Addition and Spray Drying Conditions on Some Physical Properties of Ice Cream Powder

In this study, the overall quality characteristics of ice cream powders (drying yield, moisture content, water activity, bulk density, solubility and glass transition temperature) and ice creams made from their corresponding reconstituted powders (overrun, melting behavior) were analyzed. The effect of spray drying conditions such as inlet air temperature (120, 140 and 160 °C) and feed flow rate (1.5, 3 and 4.5 mL/min) and black mulberry juice addition (15, 30 and 45 %) were included in the design. The results showed that, by increasing inlet air temperature water activity, bulk density and overrun were decreased, while solubility and melting rate of reconstituted powders were increased. Generally, mass recovery percentage of ice cream powders was decreased with increase of feed flow rate and juice concentration at the same air inlet temperature due to the stickiness problem and the low glass transition temperature of components. The following optimum process conditions with the desirability of 0.86 were determined: inlet air temperature of 140 °C, feed flow rate of 1.5 mL/min and juice concentration of 30 %.

Effect of extraction and concentration processes on properties of longan syrup

Longan (Dimocarpus longan Lour.) syrup is a novel liquid sweetener produced from longan, one of the traditional and economic fruits in the Northern of Thailand. In this research, the effect of extraction and concentration processes on properties of longan syrup was investigated. There were two extraction methods (juice extractor and hydraulic press) and three concentration methods (direct heating, steam heating and vacuum evaporation). Results overall showed that the extraction method had no significant (p ≥ 0.05) effect on longan syrup properties, while concentration resulted in the quality changes of longan syrup. Concentration using direct heating of longan juice caused reduction of sucrose content, and longan syrup dark in color. The headspace volatile compounds of longan syrup were sampled using direct headspace technique and further characterized using gas chromatography-mass spectrometry. The identified volatile compounds could be divided into two groups of aroma characteristics which were (1) floral aroma: 3-methybutyl acetate, (β)-ocimene and 2-phenylethyl alcohol and (2) caramel aroma: butyraldehyde, furfural and benzaldehyde. 2-Phenylethyl alcohol, contributing to floral odor, was retained using vacuum evaporation as a concentration method. Result revealed that the optimal concentration process for longan syrup production was vacuum evaporation, providing the highest floral volatile and lowest caramel volatile. Sensory tests confirmed that longan flavor of the syrup produced from the vacuum evaporation process had significantly higher hedonic scores than other processes.

The application of response surface methodology in studying the effect of heat and high hydrostatic pressure on anthocyanins, polyphenol oxidase, and peroxidase of mulberry (Morus nigra) juice

BACKGROUND

Mulberry juice is an excellent source of phytochemicals with medicinal properties. The effects of four independent variables (temperature, heating time, pressure, and pressurising time) on three response variables [% anthocyanin retained, and % residual activities of the enzymes polyphenol oxidase (PPO), and peroxidase (POD)] of mulberry juice were studied using response surface methodology. Mathematical models and optimum levels of the response variables were generated.

RESULTS

Temperature had the greatest effect on all the response variables. The synergistic effect of temperature and pressure had significant effect (P < 0.05) on anthocyanin retained and residual PPO activity. The prediction of the desirability model, based on 95% confidence in the range of the independent variables, gave optimal treatment conditions of 83.39°C, 2.38 min, 480.00 MPa, and 21.67 min, respectively for temperature, heating time, pressure, and pressurising time. At these levels, the corresponding response variables were 91.68%, 44.69% and 20.17% for the amounts of anthocyanin retained, and residual activities of PPO and POD, respectively. The desirability index obtained was 0.741.

CONCLUSION

The results were desirable and the mathematical models developed could be used to predict the outcome of the response variables to a high degree of accuracy.

Efficacy of sodium hypochlorite and acidified sodium chlorite in preventing browning and microbial growth on fresh-cut produce

The use of suitable sanitizers can increase the quality of fresh-cut produce and reduce the risk of foodborne illnesses. The objective of this study was to compare the washing effects of 100 mg/L sodium hypochlorite (SH) and 500 mg/L acidified sodium chlorite (ASC) on the prevention of enzymatic browning and the growth of microbial populations, including aerobic plate counts, E. coli, and coliforms, throughout storage at 4°C and 10°C. Fresh-cut zucchini, cucumbers, green bell peppers, and root vegetables such as potatoes, sweet potatoes, carrots, and radishes were used. Compared to SH washing, ASC washing significantly (p<0.05) reduced microbial contamination on the fresh-cut produce and prevented browning of fresh-cut potatoes and sweet potatoes during storage. More effective inhibition of aerobic plate counts and coliforms growth was observed on fresh-cut produce treated with ASC during storage at 10°C. Polyphenol oxidase (PPO) activity of fresh-cut potatoes and sweet potatoes was more effectively inhibited after washing with ASC. The use of 500 mg/L ASC can provide effective antimicrobial and anti-browning treatments of fresh-cut produce, including processed root vegetables.