Showing papers in "International Journal of Food Science and Technology in 2008"

Fish industry waste: treatments, environmental impacts, current and potential uses

Abstract: Fish waste management has been one of the problems having the greatest impact on the environment. Fish farming detrimental effects on the marine environment in particular have become an issue of public concern. In European Union, numerous Directives, Decisions and Regulations were voted in an attempt to minimise the environmental impact of fisheries within the frame of Integrated Coastal Management. Treated fish waste has found many applications among which the most important are animal feed, biodiesel/biogas, dietic products (chitosan), natural pigments (after extraction), food-packaging applications (chitosan), cosmetics (collagen), enzyme isolation, Cr immobilisation, soil fertiliser and moisture maintenance in foods (hydrolysates). In this review, an update of both environmental impact (inputs and outputs) and treated fish waste uses is provided by means of six comprehensive tables and seven figures.

Complexation between milk proteins and polysaccharides via electrostatic interaction: principles and applications – a review

Abstract: Summary This article details recent research conducted on the complexation between milk proteins and polysaccharides and the properties of the complexes, and the application of such relationships to the food industry. Complexation between proteins and polysaccharides through electrostatic interactions gives either soluble complexes in a stable solution or insoluble complexes, leading to phase separation. The formation and the stability of these complexes are influenced by pH, ionic strength, ratio of protein to polysaccharide, charge density of protein and polysaccharide as well as processing conditions (temperature, shearing and time). The functional properties of milk proteins, such as solubility, surface activity, conformational stability, gel-forming ability, emulsifying properties and foaming properties, are improved through the formation of complexes with polysaccharides. These changes in the functional properties provide opportunities to create new ingredients for the food industry.

Biofilms in the food industry: problems and potential solutions

Abstract: Summary Contamination of food by spoilage and pathogenic micro-organisms costs the food industry millions of dollars annually. Much of this contamination may be attributed to the presence of biofilms in the processing plant. In this review, we examine the properties of micro-organisms and the surfaces of processing equipment that influence the formation of biofilms. Of particular concern is the increased resistance of biofilms to cleaning and disinfection processes. Alternative means of controlling biofilm development are described and some aspects where more information is required are identified.

Comparison of hot air‐drying and freeze‐drying on the physicochemical properties and antioxidant activities of pumpkin (Cucurbita moschata Duch.) flours

Abstract: Summary Freeze-drying and hot air-drying were applied in the preparation of pumpkin flours to investigate the effects of drying methods on the antioxidant activities and physicochemical properties. The antioxidant activities of methanol extracts from pumpkin flours were studied in terms of total antioxidant activity, reducing power, free radical scavenging, superoxide anion radical scavenging and metal chelating activities. Hot air-dried pumpkin flour showed stronger antioxidant activities than freeze-dried flour. The percentage inhibition of peroxidation in linoleic acid system by 15 mg mL−1 extracts from hot air-dried and freeze-dried pumpkin flours was found to be 92.4% and 86.1% after 120 h of incubation, respectively. Hot air-dried pumpkin flour exhibited higher reducing power, free radical scavenging and metal chelating activities than freeze-dried flour. This study also indicated that freeze-drying significantly reduced the browning and preserved the redness of pumpkin flours. Hot air-drying reduced the oil absorption capacity, water absorption and porosity of pumpkin flours, while it markedly increased the water solubility and bulk density.

Review of mechanisms, conditions, and factors involved in the oil uptake phenomenon during the deep-fat frying process

Abstract: Deep-fat frying is a rapid and low cost process widely used to prepare tasty food. During this cooking process, oil is used both as the heating medium and as an ingredient producing calorific products. Nutrition has become a major health issue, especially in developed countries where increasing obesity is a problem, particularly among children. Many food research projects involving snack food industries therefore attempt to understand oil uptake during the frying process in order to control and reduce the fat content of fried products without deteriorating their desirable organoleptic characteristics. The main objectives of this paper are to review the literature on the frying process and more precisely the mechanisms and parameters involved in the oil uptake phenomenon. Both products and processes will be considered and their influence via experimental results will be discussed.

Carbohydrate‐based fat replacers in the modification of the rheological, textural and sensory quality of yoghurt: comparative study of the utilisation of barley beta‐glucan, guar gum and inulin

Abstract: Summary Barley beta-glucan, partially hydrolysed guar gum and inulin were used in the processing of low-fat yoghurts. The possible beneficial effects of carbohydrate fat replacers on the rheological, textural and sensory quality of low-fat yoghurt-based products were determined. Comparisons were made between the sample yoghurts made from a low-fat milk base, and full-fat and low-fat yoghurt controls. The inclusion of the carbohydrate components reduced product syneresis and improved the texture and rheological properties of the low-fat-based products so that their quality characteristics were similar to yoghurt made with full-fat milk. Both the type and also the amount of carbohydrate component altered product characteristics. Beta-glucan addition at low level (0.5%) was effective in improving serum retention of the yoghurt and its viscoelastic nature (G′, G′ and tan δ). In contrast, higher levels (above 2%) of inulin and guar gum were needed to exert significant improvements in the textural characteristics of yoghurt. Sensory analysis conducted on the samples illustrated that the inclusion of carbohydrate-based fat replacers could be successfully utilised to mimic full-fat products.

Shelf-life extension of peaches through sodium alginate and methyl cellulose edible coatings

Abstract: Summary The objective of this study was to determine the effect of sodium alginate and methyl cellulose coatings on the respiration rate, firmness, acidity, pH, total soluble solids and desiccation rate of peaches. Coated and uncoated control fruits were stored at 15 °C and 40% RH. Respiration rate, moisture loss, and changes in firmness, total titrable acidity, pH and total soluble solids of coated and control samples were determined at 3-day intervals. The respiration rate, moisture loss and changes in quality parameters were much lower in coated peaches as compared with the control. While the maximum acceptable shelf-life at 15 °C for control samples was 15 days, the coated samples maintained their acceptability up to 21 and 24 days, respectively, with sodium alginate and methyl cellulose coating. The reduced respiration and transpiration rates as a result of coatings were considered responsible for maintaining the quality and increasing the shelf-life of peaches.

Antioxidant activity of Bahraini date palm (Phoenix dactylifera L.) fruit of various cultivars

Abstract: Summary Fruits of sixteen cultivars of date palm (Phoenix dactylifera L.) commonly grown in Bahrain were evaluated for their antioxidant activity, total phenolics and ascorbic acid contents at different ripening stages using the ferric reducing antioxidant power (FRAP) assay. The highest total antioxidant activity was found at biser (unripe) stage, with a mean FRAP value of 5.71 ± 4.31 mmol/100 g fresh weight (FW), followed by rutab (soft and ripped) with FRAP values of 1.2 mmol per 100 g FW and tamer (dried fruit) 0.94 ± 0.21 mmol per 100 g FW. Total antioxidant activities of locally collected and imported tamer were similar. There was about twelve and six fold difference between cultivars possessing the highest and lowest antioxidant values at biser and rutab stages, respectively. A sharp decrease in antioxidant activity was found to be associated with the fruit ripening. The average of phenolics at biser and rutab stage were 196.8 ± 72.1 and 116.7 ± 44.1 mg per 100 g fresh weight, whereas the average of ascorbic acid was 6.6 ± 2.4 and 3.3 ± 1.3 mg per 100 g fresh weight, respectively. Significant correlation was found between the antioxidant activity and total phenolic content (r = 0.595) and ascorbic acid (r = 0.385) at biser stage, but not at rutab stage. It was concluded that the phenolics were the major contributor for the antioxidant activity.

Quality assessment of whole and gutted sardines (Sardina pilchardus) stored in ice

Abstract: Summary The quality and shelf life of whole ungutted and gutted sardines (Sardina pilchardus) stored in ice were studied. The changes in the fish were investigated by sensory assessments, chemical analyses and microbiological analyses. The sensory scores of uneviscerated and gutted sardines stored in ice at +4 °C were 7 days. The chemical indicators of spoilage, total volatile basic nitrogen and trimethylamine values of gutted sardine increased very slowly, whereas for whole ungutted samples higher values were obtained reaching a final value of 15.03–29.23 mg per 100 g and 2.36–4.16 mg per 100 g, respectively (day 9). Peroxide and thiobarbituric acid values remained lower for whole ungutted sardine samples until day 9 of storage, whereas for gutted fish were higher. The level of histamine exceeded the legal limit in whole ungutted sardine after 7 days of storage in ice, during which sardines were rejected by the sensory panel. Mesophilic aerobic bacteria count, H2S-producing bacteria, sulphide reducing anaerobe Clostridias, Enterobacteriaceae count of whole ungutted sardine samples are higher than gutted sardine samples during the storage. Psychrotrophic bacteria counts of the two groups were not different. The limits of microbiological data were not exceeded throughout the storage in both the groups’ samples.

Antioxidant activity and phenolic content of lentils (Lens culinaris), chickpeas (Cicer arietinum L.), peas (Pisum sativum L.) and soybeans (Glycine max), and their quantitative changes during processing

Abstract: Summary Total phenolic content (PC) was ∼12 mg g−1 in lentils, 2.2 mg g−1 in chickpeas, 2.3 mg g−1 in soybeans, 2.5 mg g−1 in yellow peas and 1.2 mg g−1 in green peas. Total antioxidant activity (AA) determined by ABTS (2,2′-azinobis-3-ethyl-benzthiazoline-6-sulfonic acid) assay was highest in lentils at around 14 μmol Trolox equivalent antioxidant capacity (TEAC) g−1 and lowest in green peas at 1.9 μmol TEAC g−1. Bound phytochemicals contributed to 82–85% total AA in lentils. Free phytochemicals contributed more to total AA in chickpeas, yellow peas, green peas and soybeans than bound phytochemicals. AA and PC was reduced by ∼80% in lentils and <30% in yellow peas by decortication, by 16–41% in lentils, chickpeas and peas by cooking, and by 22–42% in lentils by soaking. Total AA was significantly correlated with total PC. Soybeans had the greatest ability to scavenge free radicals, inhibit lipid peroxidation and chelate metals among the legumes tested. Different legumes exhibited different AA mechanisms.

Antibacterial activity of different essential oils obtained from spices widely used in Mediterranean diet

Abstract: Raw and processed foods are open to contamination during their production, sale and distribution. At present, therefore, a wide variety of chemical preservatives are used throughout the food industry to prevent the growth of food spoiling bacteria. However health and economic considerations have led to a search for alternatives, such as essentials oils that can safely be used as substitutes for fungicides and bactericides to partially or completely inhibit the growth of fungi and bacteria. The aim of this work was to determine the effectiveness of the essentials oils from oregano (Origanum vulgare), thyme (Thymus vulgaris), rosemary (Rosmarinus officinalis), sage (Salvia officinalis), cumin (Cuminum cyminum) and clove (Syzygium aromaticum) on the growth of some bacteria commonly used in the food industry, Lactobacillus curvatus, Lactobacillus sakei, Staphylococcus carnosus and Staphylococcus xylosus or related to food spoilage Enterobacter gergoviae, Enterobacter amnigenus. The agar disc diffusion method was used to determine the antibacterial activities of the oils. All six essential oils analysed had an inhibitory effect on the six tested bacteria. Oregano essential oil showed the highest inhibition effect followed by cumin and clove.

Effect of inclusion of soluble and insoluble fibres into extruded breakfast cereal products made with reverse screw configuration

Abstract: Summary Five dietary fibre rich ingredients were used at 5%, 10% and 15% replacement levels in a white flour cereal base to produce an extruded cereal product. The inclusion of the dietary fibres into the flour bases had no significant effect on the expansion ratio of the products. However, the bulk density of the extruded products increased with inulin addition. The pasting properties of the raw flour and fibre base as well as the extruded products were altered with the incorporation of dietary fibre, with guar gum enriched products showing elevated peak and final viscosity readings. This appeared to be related to moisture manipulation and hence the regulation of gelatinisation. In vitro starch hydrolysis of the raw bases and the extruded samples illustrated that the extrusion process significantly increased the availability of carbohydrates for digestion. Additionally, the inclusion of dietary fibres in the raw bases significantly reduced the rate and extent of carbohydrate hydrolysis of the extruded products. As such the addition of dietary fibres to extruded products reduced the amount of readily digestible starch components of breakfast products, and increased the amount of slowly digestible carbohydrates.

Simulating human carbohydrate digestion in vitro: a review of methods and the need for standardisation

Abstract: Summary Numerous in vitro carbohydrate digestion methods exist for analysis of the likely glycaemic properties of foods. Generally these methods encompass simulations of oral, gastric and intestinal digestion processes, but the way in which physiological conditions are implemented across methods differs considerably. Some differences are in the mode of comminution, inclusion and duration of a gastric digestion, and choice of amylolytic enzyme. Incubation temperature, pH, duration and stirring mode also differ between methods. Such differences, particularly the method used to mimic chewing, can have a substantial influence on the relative estimate of glycaemic potency for a given food. To achieve estimates of high predictive power, and global relevance, a validated, standardised in vitro digestion method must be developed. This article provides a systematic review of commonly used and referred to in vitro carbohydrate digestion methods. Methodological discrepancies between protocols are identified thus defining the route a systematic standardisation investigation should take.

Meat waste treatment methods and potential uses

Abstract: Meat waste management has been and continues to be one of the most important issues related to pollution management. This was due to the high concentration of meat waste materials like blood, hair, tail, horns and bones, among others that have to be thoroughly and effectively treated prior to their disposal. Methods like aerobic and anaerobic digestion [mesophilic or thermophilic temperatures, composting (windrows, aerated static piles and bins or aerated chambers)] are currently extensively used. Nowadays, the emphasis is on reusing the so-called waste materials for production processes, i.e. meat and bone meal. The latter was widely recommended and used in animal nutrition as a protein source in place of proteinaceous feeds. However, this approach greatly suffered from Small Bowel Enteroclysis (SBE) occurrence and micro-organism presence. Heavy metal absorption by means of charred bones appears to be one of the most promising applications of bones apart from other use for production of edible materials. The aim of this review was to summarise most updated references in the field of meat waste treatment and potential uses of treated waste by means of nine informative tables and six figures.

Evaluation of potential mechanisms by which dietary fibre additions reduce the predicted glycaemic index of fresh pastas

Abstract: A range of commercially available dietary fibres (DFs), representing both insoluble and soluble forms, were used in the production of pasta. Addition of fibre was at a range of levels (2.5-10%). The potential glycaemic index of these pastas was then evaluated using an in vitro model system to determine starch digestibility and sugar release. Scanning electron microscopy was used to relate structural properties of the pasta to starch degradation. The resulting predicted glycaemic indexes illustrated that the inclusion of DFs into pasta can reduce the glycaemic index of an already low GI food by up to 40%. As such, compared to the predicted glycaemic index value for the control fresh pasta (GI = 45), inclusion of pea fibre, guar gum and locust bean gum yielded pasta with GI values of 39.2, 37.9 and 37 respectively. Thus the type of dietary fibre used was important in the rate of starch digestion observed during the in vitro process. Equally, the level of fibre inclusion was of importance with an inclusion rate of 2.5% generally resulting in pasta with a predictive GI of 42.1, whereas an inclusion of 10% yielded pasta with a GI value of 37.2. Such reductions could be achieved through a number of possible mechanisms including antagonistic and synergistic relationships existing between DF's and other food components, the effect of DF's in entrapping pasta particles and thus inhibiting starch degradation, and the restriction of water movement during the cooking of pasta products, thus indicating that starch swelling is impaired.

Antioxidant activity of pomegranate rind powder extract in cooked chicken patties

Abstract: The radical scavenging activity, reducing power and phenolic composition of pomegranate rind powder extract (RP) were determined and antioxidant properties of RP was evaluated in cooked chicken patties compared with vitamin C (VC) during refrigerated storage. Freshly minced chicken meat were assigned to one of the following six treatments: control (meat without any antioxidant); RP 5, RP 10, RP 15 and RP 20 (5, 10, 15 and 20 mg equivalent RP phenolics 100 g -1 meat, respectively) and VC 50 (50 mg VC 100 g -1 meat). The RP exhibited significantly (P < 0.05) higher reducing power and 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity. Incorporation of RP into chicken patties significantly (P < 0.05) reduced the HunterLab L* values compared with control and VC patties. Total phenolic content (as tannic acid equivalent) significantly (P < 0.05) increased from 308 in control to 441 μg g -1 in RP 20 patties. Addition of RP to chicken patties did not affect any of the sensory attributes. The values of thiobarbituric acid reactive substances were significantly (P < 0.05) reduced from 1.530 in control patties to 0.135 mg malonaldehyde kg -1 samples in RP patties. Pomegranate rind powder extract treatment (RP 10, RP 15 and RP 20) substantially inhibited (P < 0.05) lipid oxidation in cooked chicken patties to a much greater extent than VC treatment. Therefore, pomegranate rind powder can be utilized as an excellent natural antioxidant source.

Physiological and biochemical changes of different fresh‐cut mango cultivars stored at 5 °C

Abstract: Summary Treatments to inhibit browning, decay and to extend shelf life of ‘Keitt’, ‘Kent’ and ‘Ataulfo’ mango cultivars as a fresh-cut produce were investigated. Combinations of calcium chloride (CaCl2), antioxidants [ascorbic acid (AA), citric acid (CA)] and two commercial film coatings resulted in a reduction of browning and deterioration of fresh-cut mangoes stored at 5 °C, especially for the Ataulfo cultivar. The use of CaCl2 + AA + CA significantly reduced colour deterioration, loss of firmness and did not affect sensory characteristics of fresh-cut mango, with a larger effect in the Ataulfo cultivar. In general, these treatments prevented loss of sugar and vitamin C of cubes during storage at 5 °C. Shelf life of this cultivar was 21 days, while that of Keitt and Kent was only 9 and 12 days, respectively. There is a correlation between carotene and vitamin C content of Ataulfo mango and its longer shelf life compared with the other cultivars.

Effect of different cooking methods on the antioxidant activity of some vegetables from Pakistan

Abstract: Summary The effects of different cooking methods (boiling, frying and microwave cooking) on the antioxidant activity of some selected vegetables (peas, carrot, spinach, cabbage, cauliflower, yellow turnip and white turnip) were assessed by measuring the total phenolic contents (TPC), reducing power and percentage inhibition in linoleic acid system. TPC (gallic acid equivalents g/100 g of dry weight) and reducing power of the methanolic extracts of raw-, microwaved-, boiled- and fried vegetables ranged 0.333–2.97, 0.52–2.68, 0.48–2.08, 1.00–2.02 and 0.391–2.24, 0.822–1.10, 0.547–1.16, 0.910–4.07, respectively. The level of inhibition of peroxidation ranged 71.4–89.0, 66.4–87.3, 73.2–89.2 and 77.4–91.3%, respectively. Antioxidant activity of the vegetables examined was appreciably affected because of varying cooking treatments. TPC of vegetables, generally, decreased by boiling, frying and microwave cooking. There was a significant (P < 0.05) increase in reducing power as a result of frying. However, boiling and microwave cooking did not affect reducing power. Inhibition of peroxidation increased by boiling and frying, whereas, in contrast it was decreased by microwave cooking. The results of the present investigation showed that all the cooking methods affected the antioxidant properties of the vegetables; however, microwave treatment exhibited more deleterious effects when compared with those of other treatments. Thus an appropriate method might be sought for the processing of such vegetables to retain their antioxidant components at maximum level.

Comparative study on antioxidative activity of yellow stripe trevally protein hydrolysate produced from Alcalase and Flavourzyme

Abstract: Summary Antioxidative activities of protein hydrolysates from yellow stripe trevally (Selaroides leptolepis) prepared using Alcalase 2.4 L (HA) and Flavourzyme 500 L (HF) with the degree of hydrolysis of 15% by pH-stat method were determined. Both protein hydrolysates exhibited the antioxidative activity in a concentration dependent manner. HF generally showed the greater antioxidative activity than HA (P < 0.05) as indicated by the higher 2,2-diphenyl-1-picryhydrazyl (DPPH) radical scavenging activity, reducing power and metal chelating activity. Antioxidative activity of both hydrolysates was stable when heated at 90 °C for 10 and 30 min and subjected to a wide pH range (2–12). Nevertheless, metal chelating activity decreased in very alkaline and acidic pH ranges. HA and HF at 200 ppm retarded the formation of conjugated diene and thiobarbituric acid reactive substances (TBARS) in lecithin liposome system. HF possessed the stronger antioxidative activity than HA (P < 0.05). However, α-tocopherol at 200 ppm showed the higher antioxidative activity in the system.

Inhibition effects of grape seed extracts on melanosis formation in shrimp (Parapenaeus longirostris)

Abstract: Summary The aim of this study was to investigate the effects of grape seed extracts on inhibition of melanosis in shrimp. Defatted grape seed powder was extracted using ethanol. Dipping solutions in five different concentrations (0, 2.5, 5.0, 10 and 15 g L−1) were prepared using grape seed extract and distilled water. The shrimps were dipped into the solutions and stored at 4 °C. Melanosis was investigated by sensory analysis and lightness, redness and yellowness values were measured by chromometer during the storage for 3 days. According to the results, grape seed extracts showed inhibition effect on the formation of melanosis. The best results were obtained with the solution of 15 g L−1.

Comparison of composition and antioxidant capacity of some cereals and pseudocereals

Abstract: Polyphenols, phenolic acids, fibres and antioxidant capacity were determined in water, acetone and methanol extracts of buckwheat, rice, soybean, quinoa and 3 amaranth cultivars. Their antioxidant activities were comparatively assessed by total radical-trapping antioxidative potential (TRAP), ferric ion-reducing antioxidant power (FRAP), cupric-reducing antioxidant capacity (CUPRAC) and nitric oxide (NO center dot) assays, which comprised of contributions from polyphenols and phenolic acids (especially from the most abundant ferulic acid). The correlation coefficients between polyphenols and antioxidant activities of cereal and pseudocereal methanol extracts with FRAP, NO center dot, CUPRAC and TRAP were 0.99, 0.97, 0.96 and 0.77, respectively. The weakest correlation was with dietary fibres, an average one exhibited with tannins and marked correlation was shown with the phenolics. All the applied methods have shown that pseudocereals have higher antioxidant activity than some cereals (rice and buckwheat) and can be successfully replaced by cereals in case of allergy.

Variation of Phenolic content in Coconut oil extracted by two conventional methods

Abstract: Summary Phenolic compounds present in the nonsaponifiable fraction of coconut oil were analysed by high-performance liquid chromatography with florescence detection. Mass spectra of the phenolic compounds were also obtained separately by LC–MS to confirm the presence of the phenolic compounds. Caffeic acid, p-coumaric acid, ferulic acid and (+/−) catechin were observed in coconut oil. Phenolic acid fraction of the coconut oil prepared by boiling coconut milk (traditional coconut oil) was more complex compared with that of coconut oil prepared by pressing copra (commercial coconut oil). Total phenol content of traditional coconut oil was nearly seven times higher than that of commercial coconut oil (618 ± 46 vs. 91 ± 11 mg kg−1), suggesting that the phenol content varies with the extraction method.

Sensory aroma from Maillard reaction of individual and combinations of amino acids with glucose in acidic conditions

Abstract: The aroma produced in glucose-amino acids (individual and in combination) Maillard reaction, under acidic conditions at 100 °C were determined and compared by trained panellist. Proline produced pleasant, flowery and fragrant aroma. Phenylalanine and tyrosine produced dried roses aroma. Alanine produced fruity and flowery odour, while aspartic acid and serine both produced pleasant, fruity aroma. Arginine, produced a pleasant, fruity and sour aroma at pH 5.2, but not at its natural pH. Glycine, lysine, threonine and valine produced a pleasant caramel-like odour. Isoleucine and leucine gave off a burnt caramel aroma. Methionine developed a fried potato odour. Cysteine and methionine produced savoury, meaty and soy sauce-like flavours. A combination of these amino acids produced different types of aroma, with the stronger note dominating the odour of the mixture. This study will help the prediction of flavour characteristics of hydrolysates from different protein sources.

Antioxidant activities of red pepper (Capsicum annuum) pericarp and seed extracts

Abstract: Summary In this study, we examined the antioxidant activities of red pepper (Capsicum annuum, L.) pericarp and red pepper seed extracts. The extracts were evaluated by various antioxidant assays, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, superoxide anion radical scavenging, hydroxyl radical scavenging, [2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid)] (ABTS) radical scavenging, ferrous chelating activity, superoxide dismutase (SOD) activity and reducing power, along with the determination of total phenolic and flavonoid contents. All the extracts showed strong antioxidant activity by the testing methods. The red pepper pericarp extract exhibited strong ferrous chelating activity and high scavenging activity against free radicals, including both the hydroxyl and DPPH radicals, but it exhibited weaker scavenging activity for the superoxide anion radical and for SOD. In contrast, the red pepper seed extract exhibited strong SOD activity and high scavenging activity against the superoxide anion radical, but showed weaker ferrous chelating activity, hydroxyl radical scavenging, and DPPH radical scavenging. We observed that the reducing power level and ABTS radical scavenging activity of the red pepper seed were higher than those of the red pepper pericarp at the highest tested concentration. Most of the test results for the red pepper seed and red pepper pericarp extracts increased markedly with increasing concentration; however, the metal chelating, SOD and ABTS radical scavenging activities did not increase with the concentration. Highest total phenolic and flavonoid contents were obtained from the red pepper pericarp extracts. Overall, the red pepper seed and red pepper pericarp extracts were highly effective for the antioxidant properties assayed, with the exceptions of ferrous chelating activity, hydroxyl radical scavenging and SOD activity.

Comparison of full‐fat and low‐fat cheese analogues with or without pectin gel through microstructure, texture, rheology, thermal and sensory analysis

Abstract: Summary The effects of pectin gel and protein base on processed semi-solid cheese analogues were studied through microstructure, texture, rheology, thermal analysis and sensory evaluation. Scanning electron microscopy revealed differences in the microstructure of processed cheese analogues. Samples made with full-fat contained higher concentrations of fat globules and were denser compared with low-fat cheese analogues with or without pectin gel. The pectin gel in the products acted as a linkage with other ingredients and made the products more compact and had less cavity compared with the products without pectin gel added. On rheological analysis, the full-fat products manifested a more solid-like form. The storage modulus of pectin gel sample was higher than that without pectin gel. All the samples’ rheological parameters were depending on the oscillatory frequency and temperature. In low-fat samples, pectin gel added or not affected the hardness, gumminess, chewiness and adhesiveness significantly. The pectin gel addition show positive effect to the texture profile of the low-fat cheese analogues. Through thermal analysis, the meltability and glass transition temperature of the processed cheese analogues were measured. The low-fat cheese analogue with pectin gel addition got the higher texture and mouthfeel scores through sensory evaluation.

Common date palm in Tunisia: chemical composition of pulp and pits

Abstract: Summary Date pulp and seeds (Phoenix dactylifera L.) of a mixture of some mature common varieties called ‘Khalti’, from the South-Eastern region of Tunisia, were evaluated for their main chemical composition. Studies were also conducted on the profiles of the extracted oil fatty acid. The following average values (on a dry-weight basis) were obtained from the pulp and pits, respectively: total sugars 63.38% and 8.12%, reducing sugars 51.56% and 6.63%, sucrose 11.82% and 1.49%, protein 3.86% and 5.31%, oil 0.26% and 8.33%. Gas–liquid chromatography revealed that the major unsaturated fatty acid was linoleic acid (32.77%) for the pulp and oleic acid (47.66%) for the pits, while the main saturated fatty acid was palmitic acid (20.55%) for the pulp and lauric acid (17.39%) for the pits. Myristic, stearic and linolenic acids were also found in both the pulp and seeds. The uses of common dates, which are currently used only for animal feed, are assessed with suggestions for potential uses as sources of nutraceutical fructose and edible, pharmaceutical oils.

Comparison of polyamine, phenol and flavonoid contents in plants grown under conventional and organic methods

Abstract: Summary The objective of this work was to compare the contents of polyamines (putrescine, spermidine and spermine), and total soluble phenols and flavonoids in parts of plants grown under either organic or conventional cropping, commonly discarded during food preparation. The contents of free polyamines, total phenols and total soluble flavonoids in peels (zucchini squash, banana, potato, eggplant, orange, lime, mango, passion fruit and radish), leaves (zucchini squash, broccoli, carrot, collard, cassava, radish and grape), stalks (broccoli, collard and spinach) and zucchini seeds were analysed. Most analysed vegetables presented higher contents of polyamines and total phenols under organic cropping, contrary to the results obtained for total flavonoids, possibly because of the cultural practices adopted.

Effect of fortification of defatted soy flour on sensory and rheological properties of wheat bread

Abstract: The objective of this study was to determine the effects of soy-fortified bread on the sensory and rheological properties. Ground defatted soy flour was blended with wheat flour at 3%, 7% and 12%. The organoleptic characteristics of soy-fortified wheat breads were carried out by taste panel. The effect of this fortification on the rheological properties of the resulting dough was investigated using farinograph and extensograph for quality assessment of the final product. The ash and protein contents of 3% and 7% wheat-soy bread blends increased compared with control. The results revealed that organoleptic characteristics score such as bendability, appearance, flavour and taste, crust texture and overall acceptability properties of bread containing 3% defatted soy flour was highest even though it is not significantly different. Therefore, we conclude that adding 3% or 7% defatted soy flour actually gives as good a loaf of bread as the 100% wheat bread with higher nutritional quality and acceptable consumer attitude with rheological and sensory characteristics.

Effects of gelatinisation level, gum and transglutaminase on the quality characteristics of rice noodle

Abstract: Summary The aim of the present study was to investigate the effects of gelatinisation level, gum (locust bean gum, xanthan gum, 3%) and/or transglutaminase (TG, 0.5%) on quality characteristics of rice noodle. In order to improve the dough forming ability, rice flour was gelatinised at levels of 15%, 20%, 25% and 30%. Noodle samples were evaluated in terms of cooking loss, total organic matter (TOM), water absorption, swelling volume, maximum force, colour, sensory properties, pasting properties. Noodle sample with a gelatinisation level of 25% had better cooking and sensory properties. Gum and/or TG were added to this noodle formula. The noodle samples including xanthan gum had better cooking and sensory properties. TG caused a significant decrease in TOM. The samples including locust bean gum had significantly higher maximum force values. Xanthan gum caused decreases in some Rapid ViscoAnalyzer viscosity values of the noodle samples, while locust bean gum caused increases.

Fluorescence spectroscopy in monitoring of extra virgin olive oil during storage

Abstract: Summary The present study demonstrates the use of fluorescence spectroscopy for monitoring changes in virgin olive oil during storage. Total luminescence and synchronous scanning fluorescence spectroscopy techniques were tested with the purpose to check their ability to monitor changes occurring in olive oil during storage in different conditions: in clear and green glass bottles exposed to light, and in darkness. Total luminescence spectra of the initial oil samples in n-hexane solutions exhibited intense peaks, one with a maximum appearing at 320 nm in emission and 290 nm in excitation, attributed to tocopherols, and another appearing at 670 nm in emission and 405 nm in excitation, belonging to the pigments of the chlorophyll group. The intensity of these emissions decreased during storage depending on the storage conditions. Additional bands appeared in oils exposed to light in the intermediate range of excitation and emission wavelengths, arising from unidentified compounds. Bands attributed to tocopherols, chlorophylls and those tentatively ascribed to phenolic compounds were observed in the synchronous scanning fluorescence spectra, allowing monitoring of the storage effects on these constituents and their quantitative assessment after appropriate calibration. The results presented confirm the capability of the fluorescence techniques to monitor the quality of oil products.