Spray dried spinach juice: powder properties

Long-term storage of pink pepper essential oil microencapsulated by chickpea protein/pectin complexes: volatile release, antioxidant and antimicrobial activities

Pink pepper essential oil was microencapsulated with chickpea protein (CP) and chickpea protein/pectin (CP-HMP) by spray drying. The reconstitution and storage properties of the powders were evaluated after drying. The impact of microencapsulation in the volatiles release, antioxidant and antimicrobial activity of oil was evaluated during 135 days of storage. CP resulted in more soluble powders (93.52%), CP/HMP resulted in denser powders (0.39 g/mL) while wall material did not influence the wettability. Free pink pepper essential oil (FEO) showed a slight loss of the predominant terpenes (α-pinene, β-pinene, β-mircene, δ-3-carene and D-limonene) after encapsulation. In general, all samples showed an increase in the volatiles release during storage. The evaluation of mass loss showed that FEO had a high release of volatiles, followed by CP and CP-HMP. The antioxidant activity of the FEO decreased (10.8 μg Trolox/mg of oil) after 135 days of storage, whereas the antioxidant activity of CP (14.9) and CP-HMP (14) increased. Both microcapsules presented antimicrobial activity against Bacillus subtilis and Staphylococcus aureus during storage. CP microcapsules had a strong inhibitory effect against the strains tested, and this advantage was even more evident in long-term storage.

Optimization of Awaze paste formulations: The effects of using spices through a mixture design approach

Previous studies have revealed the microbial quality of Awaze paste. However, limited reports describe the effect of individual spices on Awaze paste quality. A mixture design approach was used to determine the appropriate proportions, with 15 experimental points for independent variables including RP (60-90 %), GA (10-30 %), RO (5-20 %), and GI (5-10 %). The techno-functional properties, particle size, antioxidant activity (DDPH radical assay), proximate composition, iron (Fe), zinc (Zn) content, viscosity, hardness, and microbiological quality of Awaze paste were assessed. The prepared Awaze paste showed a range of characteristics, with antioxidant activity (DDPH radical assay) ranging from 11.86 % to 62.5 %, crude protein content from 6.18 % to 16.22 %, crude fat from 5.7 % to 12.6 %, crude fiber from 16.86 % to 29.06 %, total ash content from 6.32 % to 9.94 %, total carbohydrate from 41.79 % to 60.61 %, energy from 264.3 to 329.2 k cal. , iron (Fe) content from 35.59 to 108.82 mg/100g, zinc (Zn) content from 1.72 to 26.93 mg/100g, viscosity from 65.5 to 125.5 cps, hardness from 8.48 to 55.09 g, yeast and mold count from 0.83 to 2.04 log cfu/g, and total bacterial count from 1.53 to 2.61 log cfu/g. Significant differences (p < 0.05) were observed in proximate composition, techno-functional properties, particle size, antioxidant activity, physicochemical properties, and microbiological characteristics among the formulations of Awaze paste. The selected formula showed a statistically significant difference (p < 0.05) compared to the control sample. The formulation containing 74.79 % RP, 10 % GA, 10.2 % RO, and 5.0 % GI was determined to be the optimal formula with a desirability of 0.73, based on the evaluated parameters. This preferred Awaze paste had a porosity of 28.12 %, particle size of 16.49 μm, antioxidant activity of 63.63 %, crude protein content of 17.28 %, iron (Fe) content of 98.06 mg/100g, and zinc (Zn) content of 15.04 mg/100g. Therefore, this optimal blend of ingredients could be used to produce a consumer accepted Awaze paste.

Storage of spinach juice agglomerates: Physical, flow, structural, and thermal properties

The objective of this study was to investigate how the various storage temperatures affected the physical properties, flow characteristics, microstructure, and glass transition temperature of spinach juice agglomerates. For this purpose, spray-dried spinach juice powders were processed to agglomerates by using a modified fluidized bed dryer (1.6 m/s airflow rate, 60°C drying air temperature, 20 min processing time, and with different binder solutions containing agents as maltodextrin, gum Arabic, and whey powder isolate). The analyses were carried out every month throughout 6 months while the spinach juice agglomerates were stored at temperatures of 4, 20, and 35°C. The results revealed that over the storage time, the moisture content and water activity values of the agglomerates were generally under 11% and 0.6, respectively. The color values generally showed a decreasing trend depending on the storage time. The solubility times of the samples stored at 4°C were longer than those of stored at other storage temperatures. The SJA-GA had the lowest HR and CI values and thus the best flowability properties during all storage times. There was no detectable change in the structures of SJA stored at 20°C according to the storage time. Throughout the storage time, it was discovered that the glass transition temperature of all spinach juice agglomerates was remarkably similar. Overall, the investigation revealed that storage at 35°C for 6 months might be suitable because it delivered the intended outcomes such as greater flowability and cohesiveness, and shorter wettability and solubility times.

Physicochemical and bioactive constituents, microbial counts, and color components of spray-dried Syzygium cumini L. pulp powder stored in different packaging materials under two controlled environmental conditions

Currently, the demand for functional food items that impart health benefits has been rising. Blackberry (Syzygium cumini L.) fruit has high anthocyanin content and other functional attributes. However, this seasonal fruit is highly perishable, and a large proportion of it goes unharvested and wasted worldwide. Spray drying of the fruit pulp can impart improved shelf life, ensuring long-term availability for consumers to exploit its health benefits. The storage quality varies according to the type of packaging material and the storage environment. Therefore, in this study, the shelf life span of the spray-dried Syzygium cumini L. pulp powder (SSCPP) was investigated during 6 months of storage under three types of packaging materials (i.e., polystyrene, metalized polyester, and 4-ply laminates) in a low-temperature environmental (LTE) and at ambient environmental conditions. The physicochemical stability of bioactive principles (TPC and TAC), microbial counts, and color components were analyzed at 0, 2, 4, and 6 months of storage. There was a significant gradual loss of dispersibility and solubility with an increase in flowability, bulk density, and wettability during the entire storage period for all three packaging materials. The TSS, pH, TPC, TAC, and microbial counts decreased in the SSCPP both at ambient and LTE conditions during the study. Among all the packaging materials, the 4-ply laminate was found to be the most appropriate and safe for storage of spray-dried SCPP at LTE conditions.

Physicochemical, reconstitution, and morphological properties of red pepper juice (Capsicum annuum L.) powder

ABSTRACT

The aim of this study is to investigate the influence of the encapsulating agents (maltodextrin (MD), whey protein isolate (WP), and gum arabic (GA)) and their blends (MD + WP, MD + GA, WP + GA, and MD + WP + GA) on the powder yield, drying ratio, productivity, drying rate, physicochemical, bulk, reconstitution, and morphological properties of the red pepper juice powders (RPJP) and to calculate the energy efficiency of the spray dryer. A pilot-scale spray dryer (180/80 °C inlet/outlet air temperature, 392 kPa atomization pressure, 1.54 m³/min air flow rate, and a 12.0 ± 0.2°Bx feeding concentration) was used for the drying experiments. The acceptable powder yield (52.48-94.25%) and specific energy consumption values (7.39-9.72 MJ/kg H₂O) were obtained. The RPJP presented moisture content and water activity values lower than 10% and 0.367. The red pepper juice powders were found to be highly dispersible (88.34-95.18%), soluble (solubility time and index are 9.75-77.25 s and around 99%), and easly wetted (9.75-122.00 s). The average particle sizes of the RPJPs were 14.92 μm, 19.68 μm, 19.36 μm, 17.58 μm, 19.96 μm, 19.41 μm, and 18.72 μm for RPJP + MD, RPJP + WP, RPJP + GA, RPJP + MD + WP, RPJP + MD + GA, RPJP + WP + GA, and RPJP + MD + WP + GA respectively. Despite the low powder yield and high water activity value, RPJP + MD exhibited superior (bulk density, flowability, cohesiveness, wettability and solubility times) or statistically similar (productivity, moisture content, browning index, porosity, dispersibility, and hygroscopicity) properties compared to other powders.

GRAPHIC ABSTRACT

Development of yoghurt powder using microwave-assisted foam-mat drying

Yoghurt powder is widely used in industries of confectionery and baking. The production of yoghurt powder can be made by several drying methods, including freeze, spray, microwave vacuum, convective and foam-mat. In this study, the effect of varying concentrations of egg albumin (EA) on foam and powder characteristics of yoghurt were determined. Besides, microwave-assisted foam-mat drying of yoghurt was carried out to examine the effects of three microwave output powers (100, 180 and 300 W) on powder properties of yoghurt. Increased in EA concentration resulted in an increase in foam expansion and decrease in foam density. Higher foam stability (after 120 min.) was observed for foams containing 10 and 15% EA (both found as 88.24%). As powder properties, wettability and solubility times were significantly decreased with the addition of EA, while water holding capacity was increased. Change in EA concentration was significantly (p ≤ 0.05) effective on all powder properties dried at 100 W. Carr Index and Hausner Ratio values were in the range of 0.99-13.89 and 1.01-1.17, respectively. Microwave powers were significantly (p ≤ 0.05) effective on the flowability of powders containing 0, 5 and 10% EA. Yoghurt powders showed mostly excellent flow characteristics (for all concentrations of EA and microwave output powers).

Stinging Nettles as Potential Food Additive: Effect of Drying Processes on Quality Characteristics of Leaf Powders

Stinging nettle (Urtica dioica L.) is a ubiquitous, multi-utility, and under-utilized crop with potential health benefits owing to its nutritional and bioactive components. The objective of the work is to produce powders by drying wild stinging nettle leaves as a storable, low-cost functional additive to be used in bakery and ready-to-cook products. Convective drying (CD) and freeze-drying (FD) were applied on unblanched (U) or blanched (B) leaves, which were then milled to nettle powders (NPs). The obtained NPs were evaluated for selected physicochemical (moisture, color), techno-functional (flow indices, hygroscopicity), and phytochemical (pigments, phenols) characteristics as well as mineral contents. Blanching improved mass transfer and reduced the oxidative degradation of pigments during drying, but it caused a loss of total phenols content, antioxidant activity, and potassium content. As for the drying method, CD resulted in better flow properties (i.e., Carr Index and Hausner Ratio), while FD retained better the color, pigments, magnesium content, phenolic, and antioxidant parameters. Overall, the evaluated processing methods resulted in different technological properties that can allow for better evaluation of NPs as a food additive or ingredient. Among the NPs, blanched and freeze-dried powders despite showing inferior technological properties can be recommended as more suitable ingredients targeted f or food enrichment owing to better retention of bio-active components.

Chemometric strategies for nondestructive and rapid assessment of nitrate content in harvested spinach using Vis-NIR spectroscopy

The overuse of nitrogenous fertilizers leads to an increase in the nitrate content of green leafy vegetables. Consumption of food with excess nitrate is not advisable because it results in human ailment. In this study, spinach leaves were harvested from plants grown under nine varying (0 to 400 kg/ha) nitrogenous fertilizer doses. A total of 261 samples were used to predict the nitrate content in spinach leaves using Vis-NIR (350 to 2,500 nm). The nitrate content was measured destructively using the ion-selective conductive method. Partial least square (PLS) regression models were developed using whole spectra and featured wavelengths. Spectral data were pre-processed using different spectral pre-processing techniques such as Savitzky-Golay (SG) derivative, standard normal variate (SNV), multiplicative scatter correction (MSC), baseline correction, and detrending. The predictive accuracy of the PLS model had improved after pre-processing of spectral data with MSC (RPD_CV = 1.767; SE_CV = 545.745; bias_CV = -3.107; slope_CV = 0.698) and SNV (RPD_CV = 1.768; SE_CV = 545.337; bias_CV = -3.201; slope_CV = 0.698) technique, but this was not significant (P < 0.05) as compared with raw spectral data (RPD_CV = 1.679; SE_CV = 572.669; bias_CV = -7.046; slope_CV = 0.687). The effective wavelengths for measurement nitrate content in spinach leaves were identified as 558, 706, 780, 1,000, and 1,420 nm. The performance of PLS model developed with effective wavelengths also had good prediction accuracy (RPD_CV = 1.482; SE_CV = 648.672; bias_CV = -3.805; slope_CV = 0.565) but significantly lower than the performance of model developed with full spectral data. The overall results of this study suggest that Vis-NIR spectroscopy can be an important tool and has great potential for the rapid and nondestructive assessment of nitrate content in harvested spinach, with a view to ascertain the suitability of the harvest for food uses. PRACTICAL APPLICATION: Better production and brighter color of leafy vegetable drive the farming community to overuse nitrogenous fertilizer. This has resulted in higher nitrate content in vegetables. It has been widely reported that consumption of these vegetables has carcinogenic effects on human beings. The prediction of nitrate content in leafy vegetables by traditional methods is time-consuming (30 min, including sample preparation time), destructive, and tedious; moreover, it cannot be used for inline applications. This study reports spectroscopy-based rapid (<5 s) assessment technique for nitrate measurement. A multivariable PLS model was developed using wavelengths representing nitrate content. This model can be adopted by food industries for inline applications.

The effect of different drying techniques and microwave finish drying on the powder properties of the red pepper powder (Capsicum annuum L.)

The objective of this study was to investigate the effects of different drying processes (microwave, freeze, convective hot air, and vacuum drying) and microwave finish drying (FD + MD and CD + MD) on the physical and powder properties of the red pepper powder. The effect of moisture content on the powder properties and the relationship between microwave output power or drying temperature and physical and powder properties were also determined by using most common mathematical models (linear, power, logarithmic, and quadratic). Results showed that an increase in both microwave output power and temperature (for CD and VD) generally resulted in a decrease in drying time, moisture content, and chroma and an increase in bulk and tapped density values. The drying time, moisture content, and water activity values can be significantly decreased, whereas, the color values can be significantly increased by combining FD and CD with microwave finish drying (P < 0.05). The moisture content (y = - 1.94 ln(x) + 7.6455, R² = 0.9905), bulk (y = 54.224 ln(x) + 153.71, R² = 0.9705), tapped (y = 61.7 ln(x) + 225.6, R² = 0.9994) and particle densities (y = - 327.4 ln(x) + 2260.5, R² = 0.9966), and porosity (y = - 3.778 ln(x) + 89.806, R² = 0.9586) values followed a logarithmic trend depending on the increase in the convective hot air drying temperature. The inverse relationship was observed between the moisture content, bulk and tapped densities of the red pepper powders.