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Volume 13, Issue 2, 2024
Online ISSN: 2182-1054
Volume 13 , Issue 2, (2024)
Published: 18.10.2024.
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Contents
18.10.2017.
Original scientific paper
The interaction effect of mixing starter cultures on homemade natural yogurt’s pH and viscosity
Dairy yogurts are common food products consumed by people all over the world. Due to the simple process, many people have made their own natural yogurt at home. The fermentation due to the starter culture causes the textural properties of dairy yogurt. However, the literature is surprisingly scarce on the topic of starter culture interactions in the development of textural properties of dairy yogurt. This study investigated the interaction effect of three common starter cultures, Lactobacillus acidophilus, Lactobacillus bulgaricus and Streptococcus thermophiles, on the viscosity of homemade yogurt. Using Design Expert software, a 10-run mixture model experiment was designed to examine the textural properties developed by single or multiple inoculation of these starter cultures. All yogurt formulations reached the isoelectric point of milk and had pHs in the range 3.97 to 4.32. Yogurt formulations with L. acidophilus and S. thermophilus resulted in viscosities which were similar to commercial yogurt viscosity (1.77 Pa·s), while L. bulgaricus resulted in yogurt with a lower viscosity. Based on the mixture model, L. acidophilus had most influence on the yogurt viscosity, followed by S. thermophilus and L. bulgaricus. In conclusion, L. acidophilus can be used as a single starter culture or combined with other starter cultures to develop high viscosity homemade yogurt. A Combination of S. thermophilus and L. acidphilus can also be used to develop high viscosity yogurts. However, L. bulgaricus should not be inoculated alone or become a dominant ratio in multiple starter culture inoculation as it will decrease the overall homemade yogurt viscosity.
Hadi A. Dahlan, Norrakiah A. Sani
18.10.2017.
Original scientific paper
Cytotoxic, antioxidant and antimicrobial properties of red sweet pepper (Capsicum annuum L. var. Llanerón) extracts: In vitro study
Alcoholic and aqueous extracts were obtained from red sweet pepper (Capsicum annuum L.) by different methodologies to evaluate their cytotoxic, antioxidant and antimicrobial properties. Alcoholic extracts (MFP, MSd, SFP, SDP, SSd) from fresh red sweet pepper (FP) and dry pulp (DP) and seed (Sd) were obtained by maceration (M) and Soxhlet (S) equipment using methanol as extraction solvent; whereas aqueous extracts (LFP, LSd) were obtained by decoction followed by lyophilization (L). Human tumoral cell lines from breast (MCF-7 and SKBr3), prostate (PC3) and cervix (HeLa), and fibroblasts (as control) were used to determine the cytotoxic properties by the MTT assay. Antioxidant and antimicrobial properties were determined by DPPH and disc diffusion method, respectively. The extracts SDP and SFP showed the higher cytotoxic activity. The SDP extract had a significant (P < 0.05) in-vitro effect on HeLa (1.9 ± 1.4 µg/mL) and PC3 (< 1 µg/mL) cells with a moderated impact on fibroblasts (26.1 ± 1.2 µg/mL); whereas, SFP had a significant (p < 0.05) effect on MCF-7 cell line (2.1 ± 1.2 µg/mL) with a moderated impact on fibroblasts (25.9 ± 1.0 µg/mL). The higher antioxidant activity was found for MFP (80.3 ± 0.2%) and SFP extracts (75.5 ± 0.5%). Mild antimicrobial activity was only observed for alcoholic extracts. The results showed the potential of red sweet pepper (C. annuum L.) as a source of antioxidant and cytotoxic compounds, and suggest the need of further studies to isolate and characterize the bioactive compounds that impart those properties.
Rosa Raybaudi-Massilia, Alırica I. Suarez, Francisco Arvelo, Alexandra Zambrano, Felipe Sojo, Marıa I. Calderon-Gabaldon, Jonathan Mosqueda-Melgar
18.04.2017.
Original scientific paper
Extrusion cooking technology: Principal mechanism and effect on direct expanded snacks – An overview
The snack industry is one of the fastest growing food sectors and is an important contributor within the global convenience food market. Nowadays snacks and convenience foods are also consumed regularly in India. Properly designed convenience foods can make an important contribution to nutrition in societies where social changes are altering traditional patterns of food preparation. Extrusion cooking as a popular means of preparing snack foods based on cereals and plant protein foodstuff has elicited considerable interest and attention over the past 30 years. Several studies on the extrusion of cereals and pulses, using various proportions, have been conducted because blends of cereals and pulses produce protein enriched products. Special importance is placed on the physicochemical and chemical modifications of protein, starch and dietary fibre. Extruded products can be categorized for a particular application based on their functional properties such as water absorption and water solubility index, expansion ratio, bulk density and viscosity of the dough. Therefore, the literature was reviewed for effect of extrusion processing on product parameters, and nutritional and anti-nutritional properties of extruded products.
AJITA TIWARI, Jha S. K.
18.04.2017.
Original scientific paper
Vacuum-assisted microwave drying characteristics of green bell pepper
Chopped green bell pepper pieces were blanched (95 °C, 5 min) and chemically pretreated (1% potassium metabisulphite solution, 25 min at room temperature) before drying in hot air dryer (HAD) at various temperature ranges (60 – 80 °C). Three vacuum levels (200, 400, 600 mm Hg) and microwave power levels (100, 200, 300 W) were also used to dry green bell pepper samples in a vacuum-assisted microwave (VAM) (2.45 GHz, 0.8 kW) dryer. VAM drying methods offered a maximum reduction by four to five times in drying time as compared to that in HAD. The logarithmic model was found to have the best fit based on high R2 and small values of reduced χ 2 and RMSE. VAM method has higher values for effective moisture diffusivity (Deff ) and lower values for activation energy (Ea), in comparison to the HAD method.
Vivek Kumar, Shanker L. Shrivastava
18.04.2017.
Original scientific paper
Texture analysis of blanched vegetables using high- and low-speed measuring methods
Quality reductions of raw and cooked vegetables are caused by forces generated during industrial high-speed manufacturing. However, the transferability of low-speed texture measurement methods to high speed processes is limited. Therefore, analyses with a low-speed uniaxial compression test (breaking strength σ, breaking strain ε) and a high-speed pendulum test (relative fracture height ∆h) at different speeds (3.6, 4.4, 5.3 m s−1 ) were carried out. Textural values for potatoes, carrots and celeriacs (0 to 25 min cooking time) were recorded to compare the two measurement methods. Furthermore, whether the increase of textural values of blanched vegetables measured with low-speed methods, was also observable with high-speed methods, was also investigated. Low to medium rank correlation coefficients (rS < 0.659) between parameters of the two methods were calculated. In contrast to σ and ε, ∆h-values indicate a distinct initial increase as well as textural maxima between 5.0 to 12.5 min cooking time for all tested potato and carrot varieties. On the other hand, most celeriac samples did not exhibit an increase in texture with respect to cooking time. Therefore, a textural analysis at high speeds is necessary for the prediction of textural characteristics of blanched vegetables during high-speed processing in order to reduce quality degradation.
Christian Schmitt, Thomas Friedl, Nadine Mattes, Uwe Grupa, Oliver Hensel
18.04.2017.
Original scientific paper
Optimization of microwave vacuum drying parameters for germinated lentils based on starch digestibility, antioxidant activity and total phenolic content
The aim of this study was to optimize the processing parameters of pulse mode microwave-vacuum drying of germinated green and red lentils (CDC Greenland and CDC Maxim) and investigate the changes in their total phenolic content (TPC), total antioxidant activity (TAA) and In-vitro starch digestibility (SD). The lentils were germinated for 5 days and dried by a pulse mode microwavevacuum method, using 2 s to 8 s out of 10 s pulsed mode at 2000W microwave power and varying the vacuum pressure level between 15 and 45 kPa. In-vitro starch digestibility increased significantly with increased microwave power level. The TPC and TAA appeared to vary distinctively in the two varieties of selected lentils. Vacuum pressure levels did not significantly (p>0.05) affect any responses. Green lentils could be dried at 8 s microwave power and 45 kPa vacuum pressure and red lentils could be dried at 5.5 s microwave power and 42.19 kPa vacuum pressure. The microwave-vacuum drying showed great potential for the drying of germinated lentils.
Robbarts Nongmaithem, Venkatesh Meda
18.04.2017.
Original scientific paper
Rheological properties of traditional balsamic vinegar: New insights and markers for objective and perceived quality
The molecular structure of Traditional Balsamic Vinegar (TBV) undergoes shear-induced and timedependent jamming transitions due to the high solute concentration and self-assembling phenomena of high molecular size melanoidins with very-long relaxation times (12 years at least or more than 25). The purpose of this work was to perform a descriptive and quantitative evaluation of relationships between rheological properties, vinegar composition, and perceptual assessment of sensory properties according to the official sensory procedure. With this aim, vinegars having quality traits matching legal requirements for the PDO designation were analyzed for their reducing sugars (glucose and fructose), volatile acidity, fixed acidity, pH, Brix degree, and density as well as for their flow behaviour and dynamic viscosity over a wide range of shear rates. Results showed that flow behaviour of TBV was affected by jamming properties over wide-scale ranges of shear rate producing flow instability below a shear rate of 60 s−1 . Homogeneous, continuous flow was found at medium-high shear rates with thickening and/or thinning traits. A common onset for the structure scaling was mathematically estimated to occur close to when the density was 1.32 gmL−1 . Comparative analysis of rheological, compositional and sensory properties suggested that the colloidal jamming of the vinegar melanoidins dominated the total olfactive and gustative stimuli, and determined the classification of the vinegars that had a higher dynamic viscosity but more homogeneous flow as being of the highest commercial quality category. A robust statistical model was proposed encoding for the top-down decision-making process for quality assignment according to the official sensory procedure, using composition and flow properties as predictor variables.
Pasquale Falcone, Elisa Sabatinelli, Federico Lemmetti, Paolo Giudici
01.12.2016.
Professional paper
Effect of Grewia venusta FRESEN mucilage on the proximate composition, physical and sensory properties of bread produced from wheat and cassava composite flours
Arubi P. Alobo, Gibson L. Arueya
01.12.2016.
Professional paper
Effect of tuna skin gelatin-based coating enriched with seaweed extracts on the quality of tuna fillets during storage at 4 °C
Milene Vala, Ana Augusto, André Horta, Susana Mendes, Maria M. Gil
01.12.2016.
Professional paper
Influences of physicochemical stresses on injury and inactivation behaviour of Listeria innocua
Fátima A. Miller, Bárbara Ramos, Maria M. Gil, Teresa R.S. Brandão, Paula Teixeira, Cristina L.M. Silva