Contents
18.04.2017.
Original scientific paper
Effect of pretreatments and processing conditions on anti-nutritional factors in climbing bean flours
It is difficult for many Rwandans to utilize climbing bean seeds (Phaseolus vulgaris L.) mainly because of longer cooking time (2 hours) and the high consumption of basic fuel. Climbing beans also contain anti-nutritional factors such tannins, phytates, trypsin inhibitors and phytohemagglutinins that limit nutrient absorption. One way to solve this problem is to utilize the flour of climbing beans made from different treatments and processing methods. In this study, climbing beans were pre-treated by soaking them in water for 24 hours, soaking in 2% sodium bicarbonate solution and steam blanching for 10 minutes. After that, pre-treated climbing beans were processed into flours by processing methods such as roasting, cooking and germination where anti-nutritional factors were reduced. The pretreatments did not significantly (p>0.05) affect phytates in climbing bean flours but processing conditions significantly (p<0.05) reduced it. Pretreatments and processing conditions significantly (p<0.05) reduced tannin content. The pretreatments followed by different processing conditions significantly (p<0.05) decreased trypsin inhibitors content. The great significant decrease in phytohemagglutinins content was observed in pretreatment followed by different processing methods. All pretreatments and processing conditions effectively decreased anti-nutritional factors at low level. However, pretreatments or untreated followed by germination and roasting were found to be the most and the least effective respectively. Making flour from germinated climbing bean seeds is a good option for sustainable food processing as it reduces anti-nutritional factors. It is an inexpensive method in terms of time, energy and fuel for Rwandan households, restaurants and industries where climbing bean seeds are integral part of daily meal.
Emmanuel Mugabo, Emmanuel Ohene Afoakwa, George Annor, Bernard RWUBATSE
01.12.2016.
Professional 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, Alírica I. Suárez, Francisco Arvelo, Alexandra Zambrano, Felipe Sojo, María I. Calderón-Gabaldón, Jonathan Mosqueda-Melgar
01.12.2016.
Professional paper
Evaluation of physical, milling and cooking properties of four new rice (Oryza sativa L.) varieties in Nigeria
This comparative study investigated some physical, milling and cooking properties of four new rice varieties (FARO 44, FARO 52, FARO 60 and FARO 61) in Nigeria. The varieties were processed into white rice and their properties analyzed separately using standard procedures. Results showed that paddy length, paddy-length-to-width-ratio, equivalent diameter, sphericity, grain volume, aspect ratio, thousand paddy grain weight, milled rice length, milled rice width, milled rice length to width ratio, milling recovery, head milled rice, broken milled rice, L*, a*, b*, elongation ratio, cooked-rice-length-to-breadth-ratio, water uptake ratio and cooking time were significantly different (p<0.05) for all the varieties. Milling recovery was found to vary from 65.3 to 68.33%; with FARO 60 having the highest head milled rice. It was observed that FARO 44 had the longest cooking time, elongation ratio and cooked rice length/breadth ratio while FARO 61 was found to have the highest water uptake ratio. There was significant positive correlation (r = 0.824) between percentage head milled rice and milling recovery while negative correlation existed between cooking time and L* (r= - 0.711). This information could be exploited by rice processors in the post-harvest processing of the varieties.
Mayowa S. Sanusi, Rahman Akinoso, Nahemiah Danbaba
01.12.2016.
Professional paper
Drying characteristics of zucchini and empirical modeling of its drying process
The aim of the study was to dry zucchini (Cucurbita pepo) by two different methods (convective hot-air (CHD) and microwave-assisted drying (MWD)). The effect of air temperature (60, 70 and 80°C), microwave (MW) power (180, 360, 540 W) and sample thickness (5 and 10 mm) on some drying characteristics of zucchini were investigated. Thirteen mathematical models available in the literature were fitted to the experimental moisture ratio data. The coefficients of the models were determined by non-linear regression analysis. It was determined that the model that fits the moisture ratio data the best varies at different drying conditions. Increasing drying temperature and MW power and reducing sample thickness improved the drying rate and drying time. Drying in microwave has reduced the drying time by 52-64% for zucchini. It was found that the effective moisture diffusivities increased with increasing temperature and MW power. MWD samples had better rehydration ratios compared to ones dried only in tray drier for 5 mm thickness.
Naciye Kutlu, Asli Isci
01.12.2016.
Professional paper
In vitro investigation of antioxidant activities of Launea taraxacifolia and Crassocephalum rubens
Launea taraxacifolia and Crassocephalum rubens are among many wild, underutilized and under cultivated vegetables in Nigeria that are at risk of extinction. Total flavonoid contents (TFC), total phenolic contents (TPC), and antioxidant activities of different concentrations (1-5 mg ml-1) were evaluated; using in vitro assays to assess the scavenging properties of 2, 2-diphenyl-1-picryl hydrazyl (DPPHRSP), nitric oxide (NORSP) and hydroxyl (OHRSP). Phenolic profiles of the alcoholic extracts were characterized using high-performance liquid chromatography techniques. The results revealed higher TFC (mg/100g RE) in aqueous (6.06± 0.02-78.79±0.01) than alcohol extracts (with methanol 0.93±0.01—12.73±0.04, and with ethanol -0.85±0.01-- 7.70±0.03). In a similar trend, OHRSP (%) was higher in aqueous extracts (40.83±0.10--91.74±0.19) than alcoholic extracts (with methanol -11.67±0.3-- 30.83±0.06; and with ethanol -14.42±0.06- 40.27±0.05). TPC (mg/100g GAE) which was higher in alcoholic extracts (with methanol -21.48±0.01--133.20±0.16 and with ethanol -9.45±0.01--59.73±0.02) than aqueous extracts (14.83±0.01--52.64±0.03) was in agreement with the trend observed for NORSP (28.24±0.05-151.76±0.08 for methanolic extracts, 21.99±0.13--49.93±0.04 for ethanolic extracts and 38.47±0.11--86.15±0.05 for aqueous extracts). DPPHRSP was also higher in alcoholic extracts (methanolic -22.81±0.01-48.41±0.05 and ethanolic-- 14.53±0.01-62.68±0.07) than aqueous extracts (13.66±0.13--42.86±0.03). TFC, TPC and antioxidant activities showed concentration dependent increase and strong positive correlation with TFC (r= 0.926 – 0.997and r= 0.432 – 1.000) and TPC (r= 0.825 – 0.999 and r= 0.473 - 0.994) for L. taraxacifolia and C. rubens respectively. Caffeic acid, chlorogenic acid, ellagic acid, quercetin and kaempferol were identified as major phenolic components in the extracts. The vegetables have high antioxidant potential for promoting good health; which could be attributed to the identified phytochemicals in them.
Funmilayo B. Borokini, Lajide Labunmi
01.12.2016.
Professional 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 microwave-vacuum 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
01.12.2016.
Professional paper
Microbial quality and shelf life prediction of vacuum-packaged ready to eat beef rounds containing gum arabic
Research has shown that gum arabic from Acacia senegal var. kerensis can be used in beef rounds, at a level of 2.5% of the formulated product weight, as a binder and texture modifier. However, the effect of gum arabic addition on the microbial quality and shelf life of the resulting meat product has not yet been reported. Thus, the objective of this work was to study the microbial quality of beef rounds containing 2.5% gum arabic and to study shelf life based on the growth parameters of Total Viable Counts (TVC) and Lactic Acid Bacteria (LAB). Beef round samples were injected at 30% with curing brines containing gum arabic and cooked through boiling. The growth kinetics of LAB and TVC were studied for vacuum packaged sliced beef round samples stored at 7 oC and 15 oC for a period of 21 days. Baranyi and modified Gompertz models were used to fit the LAB and TVC data obtained using DMFit. Results of microbial analysis indicated that coliforms, yeasts and molds as well as pathogenic bacteria; Salmonella, Escherichia coli, and Staphylococcus aureus, were below detection limit. In addition, TVC and LAB were found to be 1.87 ± 1.09 and 1.25 ± 0.75 Log 10 CFU g-1, respectively. The results of accuracy analysis showed that both the Baranyi and modified Gompertz models were adequate in representing the bacterial growth in beef rounds injected with curing brines containing gum arabic. The predicted shelf life was found to be between 84.3 – 88.1 h and 158.0 – 173.1 h at 15 oC and 7 oC, respectively.
Johnson K. Mwove, Symon M. Mahungu, Lilian A. Gogo, Ben N. Chikamai, Mary Omwamba
01.12.2016.
Professional 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 time-dependent 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 quantitativeevaluation 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 60s-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 M. Falcone, Elisa Sabatinelli, Federico Lemmetti, Paolo Giudici
01.12.2015.
Professional paper
Natural antioxidants isolated from Schinus areira leaves by ultrasound-assisted extraction
The aim of this study was to optimize the extraction of antioxidant compounds from Schinus areira leaves using ultrasound assisted extraction and response surface methodology. The effect of sonication time and plant material:solvent ratio were used to optimize the recovery. Results showed that a high recovery of antioxidant compounds from leaves of three different S. areira specimens was achieved under optimized conditions. The leaf extracts obtained displayed a DPPH (1,1-Diphenyl-2-picrylhydrazyl) radical scavenging activity analogous to the well-known antioxidant trolox (EC50 = 23-46 vs 36.1 µg/mL, respectively). In addition, these extracts showed a good potency to eliminate superoxide and nitric oxide-radicals as well as a moderate antimicrobial activity against gram positive Staphylococcus aureus and Enterococcus faecalis and yeast. HPLC chromatography analysis of the three S. areira leaf extracts showed different high contents of kaempferol-3-O-rutinoside, quercetin-3-O-galactoside and 3-O-caffeoylquinic acid. The results showed that the S. areira leaf extracts contained a high amount of antioxidant phenolic compounds, which might be a valuable source to be used as additives in plant-based foods.
Liliana S. Celaya, Carmen I. Viturro, Luís R. Silva, Silvia Moreno
01.12.2015.
Professional paper
The Atlantic diet – Origin and features
Despite globalization there still are food patterns which are clearly differentiated from one region to another in Europe and elsewhere. In this study the Atlantic Diet is considered as thetraditional diet in Portugal and Galicia, a regionin northwest Spain.This paper aims to contribute to a better understanding of the Atlantic Diet food pattern in order to fully exploit the potential of this Atlantic gastronomical heritage.The background of the Atlantic Diet concept, the characterization of Atlantic Diet foods and a compilation of scientific findings related to the consumption of these foods are covered.A brief description of the Mediterranean Diet, the primitive pattern and the updated Mediterranean pyramid are also included in order to aid understanding of the globalization of this previously local health food pattern.Final remarks and suggestions for further studies are made.
Manuela L. Vaz-Velho, Rita Pinheiro, Ana Sofia Rodrigues
