Contents
01.12.2018.
Professional paper
Stability of vitamin C in broccoli at different storage conditions
In this study, the retention of vitamin C in fresh broccoli stored at different temperatures (i.e. chiller, room, cooking, and roasting or baking; 5-120°C) was investigated. The thermal stability of vitamin C in broccoli was analysed at 5, 20, 45, 60, 70, 80, 110, and 120°C. The vitamin C content was measured by the indophenol titration method. Vitamin C was affected negatively at all stored temperatures. The degradation of vitamin C was modelled by first-order reaction kinetics and the reaction rate constants were observed as 9.03×10-8 and 5.65×10-3 s-1 when stored at 5°C and 120°C, respectively. The activation energy was estimated as 74.2 kJ/mol within the temperature range used in this study. The lowest decay of vitamin C was observed during the chilling condition. The data on retention of vitamin C in broccoli could be used to determine their stability, when stored as raw, and when heated at different temperatures.
Nasser Al-Habsi, Sithara Suresh, Amani Al-Yhmedi, Marwa Al-Shoryani, Mostafa I. Waly, Mohammad Shafiur Rahman
01.12.2018.
Professional paper
Non-fermented synbiotic drink based on lactic cheese whey which incorporates Lactobacillus rhamnosus GG and Lactobacillus paracasei
The use of acid whey in food formulations is one way to reduce the environmental problems associated with its disposal. In the present study, a new formulation of a drinking dessert was prepared using Lactic cheese whey, milk, xanthan gum at 4 levels (0, 0.1, 0.2 and 0.3%), resistant corn starch at 4 levels (0, 0.5, 1 and 1.5%), cocoa powder and sugar. Samples containing starch and gum had higher viscosity and were completely stable, with no syneresis and sedimentation after a month of storage at 4 °C. Samples containing 0.3% xanthan gum and 1% corn starch were considered as the desired drink based on sensory analysis. Study of the optimal flow behavior indicated that the drinking dessert is a non-Newtonian pseudoplastic fluid, and the Herschel-Bulkily model was the best model to describe the flow behavior. The pH of the synbiotic dessert containing L. GG was almost constant after 7 days of storage at 4 °C, while the pH of samples containing L. paracasei decreased by 0.7. The population of both probiotic bacteria decreased during storage time at 4 °C. The rate of decrease was higher for L. paracasei than L. GG. However, both contained >106 CFU mL-1, which is necessary for the health benefits of probiotic bacteria.
Sima Taheri, Morteza Khomeiri, Mehran Aalami, Ali Moayedi
01.12.2018.
Professional paper
Potentials of African nutmeg (Monodora myristica) as a flavourant in cookie production
African nutmeg, a possible local substitute for a commercial food flavourant, remains largely underutilized in Nigeria. Its application potential in cookie production was investigated in this study. African nutmeg (Monodora myristica) seed flour (ANM) was produced using standard method. The flour was substituted for vanilla flavour (VFL) in ratio of 0, 1, 2, 3, and 3.5 g and functional properties of the flour blends (water absorption capacity (WAC), oil absorption capacity (OAC), and bulk density) were determined, using standard methods. Cookies were developed and characterized chemically, physically (colour) and organoleptically using the AOAC method, a colourimeter and sensorypanellistsrespectively. Data were analysed using ANOVA at p<0.05. Replacement of vanilla with African nutmeg had no significant effect on bulk density (0.62g/cm3 – 0.68 g/cm3), but significantly affected WAC (133-142%) and OAC (147-156%) of flour blends. Crude protein (9.44-15.49%), crude fat (3.17-6.50%), total ash (2-2.73%) and crude fibre (0.12-0.23%) contents of the cookie increased, whilst metabolizable energy (385.33-367kcal) decreased. There were reductions in pH (6.83-6.53) and TSS (5.80-1.20). Brown index of the snack increased with addition of nutmeg. Antioxidant indicators (flavonoids, DPPH and phenol) varied among cookie samples. Antinutrients, saponin, tannin and oxalate, were within tolerable limits. All cookie samples were judged acceptable by the panellists, with SLZ being the most acceptable. An acceptable and nutritious snack was produced at 100% replacement. M. myristica seed could serve as substitute for vanilla in the production of cookies and other related snacks.
Kazeem K. Olatoye, Omololo O. Fapojuwo, Joshu A. Olorunshola, Julianah O. Ayorinde
01.12.2018.
Professional paper
Study of the self-stabilization ability of Tzatziki (a traditional Greek ready-to-eat deli salad)
Traditional Greek yogurt-based salad Tzatziki is one of the most popular ready-to-eat deli salads in Greece. The objective of this study was to estimate the microbial stability of Tzatziki, with and without chemical preservatives, using a rapid method. Determination of the microbial count was carried out using the bioluminescence method (ATP) and traditional microbiological analysis, plate-counting method (CFU) in various batches of the final product of Tzatziki. The results showed that the Tzatziki salad without preservatives initially gave higher relative light units (RLU) values (79,532) than the same salad with preservatives (43,198) because the potassium sorbate and the sodium benzoate, used in recipe, appeared to suspend the action of microorganisms. After incubation in two different substrates, MacConkey and Sabouraud, the Tzatziki salad without preservatives gave higher RLU values (9,488 and 16,176, respectively) than the salad with preservatives (12,780 and 12,005, respectively). In the two selective substrates, differences appeared between the two methods of microbial count (RLU and CFU). While RLU values were roughly at the same level, the CFU values presented significant differences (p < 0.05). It was also shown that there was a strong correlation (R2 = 0.93-0.95) between bacterial counts estimated by traditional CFU and ATP methods. As expected, the dominant microbial population in Tzatziki was Lactobacillus spp., originated from yogurt. Coliforms and yeasts were not able to survive in this environment. Generally, according to the results, Greek traditional Tzatziki salad was a microbial stable product and the bioluminescence method could be a rapid method to determine its microbial state.
Stavros Lalas, Vassilis Athanasiadis, Ioanna Karageorgou, Eleni Bozinou, Vassilis G. Dourtoglou
01.12.2018.
Professional paper
Use of response surface methodology (RSM) for composite blends of low grade broken rice fractions and full-fat soybean flour by a twin-screw extrusion cooking process
In this study, seventeen (17) composite blends of broken rice fractions and full-fat soybean, formulated using response surface methodology and central composite design within a range of barrel temperatures (100-140 °C), initial feed moisture content (15-25%) and soybean composition (8-24%), were extruded with a twin-screw extruder and the expansion and color indices were optimized. The results indicated a significant (p<0.05) effect of extrusion conditions on the responses. Fitted predictive models had coefficients of 88.9%, 95.7%, 97.3%, 95.4% and 95.2%, respectively, for expansion index, bulk density, lightness, redness and yellowness. The p-value and lack-of-fit tests of the models could well explain the observed variability and therefore could be used to establish production setting for the twin-screw extruder. The optimum extrusion conditions were found to be 130 °C (barrel temperature), 20% (feed moisture level) and 23% feed soybean composition and optimum responses in terms of bulk density, expansion index, lightness, redness and yellowness chroma indices were 0.21 g cm-3, 128.9%, 17.1, 3.13 and 24.5 respectively. This indicates that optimum conditions can be established in twin-screw extrusion cooking of broken rice fractions and full-fat soybean composite blends that can result in product of low bulk and maximum expansion with a satisfactory light yellow product color that can be used to produce products that valorize broken rice and reduce qualitative postharvest loss.
Nahemiah Danbaba, Iro Nkama, Mamudu Halidu Badau
01.12.2018.
Professional paper
Physico-chemical composition and antimicrobial protein content of early lactation donkey milk
The influence of early lactation on chemical composition and the concentration of antimicrobial proteins of donkey’s milk produced in Cyprus were investigated. Milk samples from 10 female donkeys in their first season of lactation were collected at 7, 15 and 30d postpartum. The average contents of donkey milk gross composition were 1.40% protein, 0.16% fat and 8.74% total solids. Results showed that lactation had a significant negative effect on protein concentration, while total solid concentration showed an increased followed by a decrease. Composition of antimicrobial proteins also showed a significant decreased during lactation period except from lactoferrin which showed an increase. On the other hand, throughout the lactation, pH and fat were constant.
Maria Aspri, Kallis Souroullas, Christina Ioannou, Photis Papademas
01.12.2018.
Professional paper
Effect of osmotic drying on physicochemical properties of pansies (viola × wittrockiana)
The objective of this work was to study the effect of osmotic drying, using different hypertonic solutions (sucrose and sodium chloride), on physicochemical characteristics of pansies (Viola × wittrockiana). The same treatments were applied to lettuce to compare the behavior of flowers with other vegetables. Pansies' superhydrophobic surface structure, called papillae, increased the resistance to exchanges with hypertonic solutions. No weight loss was observed after most treatments (sucrose: between 2.2 and 6.8 %; NaCl: between -23.0 % and 1.5 %), aw maintained high values (>0.94) and monomeric anthocyanins were preserved (fresh 0.10 and 0.19 mg Cy-3glu/g fresh matter for 20%/1 h in NaCl and 60%/1 h in sucrose). When applying more drastic conditions, as sodium chloride for more than 1 hour, undesirable textural and color changes were observed. For lettuce, all treatments caused osmotic dehydration, weight loss (ranged between -9.3 to -30.3 % for 80%/1 h in sucrose and 15%/1 h in NaCl) and a reduction on aw (<0.97) and carotenoids, with sodium chloride causing more damage in visual appearance than sucrose. Therefore, immersion in osmotic solutions can be applied to lettuce but the desired effect was not achieved for pansies due to the morphological structure of the flowers' epidermis.
Luana Fernandes, Susana Casal, Agostinho Magalhães, Paula Baptista, José A. Pereira, Jorge A. Saraiva, Elsa Ramalhosa
01.12.2018.
Professional paper
Development and incorporation of nanoemulsions in food
Currently, nanoencapsulation of bioactive compounds is promising, and is one of the methods that has been proven very effective. The development of food-grade nanoemulsions is in a state of constant innovation due to the interesting features that this method of encapsulation has, such as small droplet size, kinetic stability and appearance. With this technology, it is possible to control some food properties, such as texture, taste and stability. In this article, we present a review of the most commonly used methods in the creation of nanoemulsions, the recent developments of these dispersions, the relevant applications of nanoemulsions in food matrices, the most commonly used food-grade materials and the functionality of nanoemulsions, which are designed primarily to encapsulate compounds with biological activity. Nanoemulsions have been shown to be effective in preventing degradation and improving the bioavailability of bioactive compounds, such as oil-soluble vitamins, antimicrobials, flavours and antioxidants. At the end of this article, facts of interest about acceptance issues and nanotechnology regulatory policies in the food industry are presented.
Antonio de Jesus Cenobio-Galindo, Rafael G. Campos-Montiel, Rubén Jiménez-Alvarado, Isaac Almaraz-Buendía, Gabriela Medina-Pérez, Fabián Fernández-Luqueño
01.12.2018.
Professional paper
Moisture sorption isotherm and thermal characteristics of freeze-dried tuna
Water activity is considered an important factor in assessing the stability of food. Understanding the relationship between water activity and equilibrium moisture content (moisture sorption isotherm) benefits food processing in terms of modeling of drying and estimation of shelf life. In addition, glass transition helps to quantify molecular mobility which helps in determining the stability of food. The aim of this study was to determine the moisture sorption isotherm and thermal characteristics of freeze-dried tuna. These characteristics will help in determining the monolayer moisture and glassy state of the product, at which food is considered most stable. Moisture sorption isotherm at 20°C and thermal characteristics (over a wide temperature range i.e. from -90 to 250 °C) of freeze-dried tuna flesh were measured. Isotherm data were modeled by BET (Brunauer-Emmett-Teller) and GAB (Guggenheim-Anderson–De Boer) models. The GAB and BET monolayer water values were determined as 0.052 and 0.089 g g-1 dry-solids (dry-basis), respectively. In the case of samples at moisture contents above 0.10 g g-1 (wet basis), DSC (Differential Scanning Calorimetry) thermograms showed two-step state changes (i.e. two glass transitions), one exothermic peak (i.e. molecular ordering) and another endothermic peak (i.e. solids-melting). However, the sample at moisture content of 0.046 g g-1 showed three-step state changes (i.e. three glass transitions). The multiple glass transition could be explained by the natural heterogeneity of tuna flesh and inhomogeneity due to molecular incompatibility of the different compositions. The moisture content did not affect the first glass transition temperature nor the exothermic peak (p>0.05), whereas the third glass transition temperature decreased (i.e. plasticized) with increasing moisture content (p<0.05). The solids-melting peak temperature decreased, and enthalpy increased with decreasing moisture content (p<0.05).
Mohammad Shafiur Rahman, Mohammed Khalfan Al-Khusaibi, Kutaila Abbas AL-Farsi, Ismail Mohamed Al-Bulushi, Aisha Abushelaibi, Nasser Al-Habsi
18.10.2018.
Original scientific paper
Antioxidant activities of aqueous extracts from nine different rose cultivars
Rose petals have been applied as food additives in teas, cakes and flavor extracts. The aim of this research study was to explore and reveal the antioxidant potential of aqueous extracts of rose petals belonging to nine genotypes of rose (wild as well as hybrid). The in vitro antioxidant activities of roses were studied by lipid peroxidation assay, DPPH radical scavenging assay, iron chelation assay, phosphomolybdenum reduction assay and total phenolic and flavonoid contents. The aqueous extract showed inhibition against lipid peroxidation (TBARS), induced by prooxidants (10 µM FeSO4) in mice liver homogenate. The free radical scavenging activities of the extracts were determined by scavenging of the DPPH radical. Extracts also showed metal chelating activities and high antioxidant activity in the phosphomolybdenum assay. The high content of phenolics and flavonoids detected in aqueous extracts may be responsible for the antioxidant activity. Amongst the different rose genotypes, screened, Rosa moschata (musk rose) was found to carry slightly higher antioxidant potential, owing to its higher phytochemical content.
Hamadia Khurshid, Syed Mubashar, Shahid Iqbal Awan, Syed Rizwan Abbas, Muhammad Irshad
