Etelka Dimić

The effect of temperature and wax content on the appearance of turbidity in sunflowerseed oil

Turbidity in refined sunflowerseed oil, caused by the presence of waxes, is a frequent occurrence. As such, it is a special problem in a number of countries where clear packaging is used for this oil. The application of cold test for the determination of sunflowerseed oil clarity is not always satisfactory, as the negative cold test is not a guarantee that the waxes are completely removed and that the oil will remain clear for a longer period. In this study, the threshold value for wax content which would cause turbidity in refined sunflowerseed oil was determined. At the same time, the influence of cooling temperature and wax content on the visible turbidity appearance rate was investigated. The results show that the turbidity threshold for the cold test is 80 mg wax/kg oil, and that the rate of the visible turbidity appearance of the oil depends both on wax content and cooling temperature.

Effects of Hemp (Cannabis sativa L.) Seed Oil Press‐Cake and Decaffeinated Green Tea Leaves (Camellia sinensis) on Functional Characteristics of Gluten‐Free Crackers

UNLABELLED A mixture, simplex centroid, 2 components experimental design was used to evaluate the addition of hemp seed oil press-cake and decaffeinated green tea leaves, as functional ingredients to assess nutritional characteristics and antioxidant properties of gluten-free crackers. All samples with added hemp flour had much better nutritional qualities than the brown rice flour crackers in terms of higher protein, crude fibers, minerals, and essential fatty acids content. Likewise, all samples with added decaffeinated green tea leaves had much better antioxidant properties than crackers with no added green tea leaves. All crackers with added hemp flour had a significantly increased fiber content (39% to 249%) and decreased carbohydrate content (8.4% to 42.3%), compared to the brown rice flour crackers. All samples had antioxidant properties, even without the addition of green tea leaves. Optimization of the responses was conducted based on the maximized values for protein, fibers, omega-3 fatty acids content, as well as for the antioxidant activity and overall score. The suggested values for the addition of the hemp oil press-cake was 20% (total flour weight) with 4 g of decaffeinated green tea leaves that would provide protein content of 14.1 g/100 g; fibers content of 8.4 g/100 g; omega-3 fatty acids content of 3.2 g/100 g; antioxidant activity measured via 2,2-diphenyl-1-picrylhydrazyl value of 30.3 μmol TE/g d.w.; and an overall score of 8.9. This formulation has demonstrated potential application in the baking industry and marketing of these gluten-free crackers as a value-added functional product. PRACTICAL APPLICATION Hemp seed oil press-cake as a by-product of cold-pressed oil processing and brown rice flour were used to design a functional gluten-free snack-type product-savory crackers. All crackers were high in minerals, fibers, and omega-3 fatty acids with a desirable omega-6/omega-3 fatty acids ratio. Green tea leaves were added to improve antioxidant activity, which greatly contributed to their functional properties. This qualified the crackers as a healthy snack with a minimal content saturated fatty acids and an abundance of polyunsaturated and monounsaturated fatty acids that originated from chia seeds residual oil present in the hemp flour.

CHARACTERISTICS OF BLACKBERRY AND RASPBERRY SEEDS AND OILS

This study is concerned with the determination of technological quality characteristics of dried pomaces, i.e. blackberry and raspberry seeds, along with the quality parameters, content of total carotenoids and chlorophyl and transparency of crude extracted oil (using organic solvent). Blackberry seeds (Rubus fruticosus L.) were obtained from a domestic variety Cacanska bestrna, while the raspberry seeds (Rubus idaeus L.) were of the variety Willamette. Oil content of the blackberry pomace was 13.97 and 14.34%, while the oil content of the raspberry pomace was 13.44 and 14.33% on dry basis (d.b.). In regard to technological characteristics of the pomaces, i.e. volumetric and specific weight, no considerably difference was found. However, a weight test for 1000 seeds showed a significant difference in weight: 3.5 g (d.b.) for the blackberry pomace and 1.5 g for the raspberry pomace (d.b.). Proximate analysis of blackberry seed oil showed that this oil had better quality since the FFA value was 3.43% (sample B1) and 3.53% (sample B2), while the peroxide value was 8.89 and 11.16 mmol/kg, respectively. Raspberry seed oil had higher FFA (8.59 and 8.83% for sample R1 and R2) and peroxide values (13.99 and 13.84 for sample R1 and R2) than the blackberry seed oil. Crude extracted blackberry seed oil had a brown-greenish color due to the high total chlorophyll content (around 3000 mg/kg dissolved in cyclohexane). Raspberry seed oil had a dark yellowishorange color, due to lower chlorophyll content (around 200 mg/kg) compared to the blackberry seed oil, while the content of total carotenoids was slightly higher in this oil (around 40 mg/kg) compared to the blackberry seed oil (33 mg/kg). [Projekat Ministarstva nauke Republike Srbije, br. TR 31014: Development of the new functional confectionery products based on oil crops]

Pretreatment efficiency for physical refining of sunflowerseed oil

The appropriate pretreatment of crude oil is of crucial significance for the application of physical refining. This paper presents a simplified process for the preparation of sunflowerseed oil by applying multistep acid degumming as the only pretreatment step. Amorphous silica hydrogel was used instead of treatment with bleaching earth. The results obtained showed that samples of crude-pressed and extracted sunflowerseed oil differ significantly with respect to the content and composition of phosphatides, which is important for the pretreatment. The proper choice of oil and the application of multistep acid degumming results in an effective pretreatment of sunflowerseed oil for physical refining.

Development of a Hull-Less Pumpkin (Cucurbita pepo L.) Seed Oil Press-Cake Spread

UNLABELLED A stable, oil-based spread rich in the omega-3 (ω-3) and omega-6 (ω-6) fatty acids was developed using a hull-less pumpkin seed (Cucurbita pepo L.) oil press-cake, a by-product of the pumpkin oil pressing process, along with cold-pressed hemp oil. Response surface methodology (RSM) was applied to investigate the effects of two factors, as the formulations compositional variables: a commercial stabilizer (X(1) ) and cold-pressed hemp oil (X(2) ) added to the pumpkin seed oil press-cake in the spread formulations. A central composite, 2-factorial experimental design on 5 levels was used to optimize the spreads where model responses were ω-3 fatty acids content, spreadability (hardness), oil separation, and sensory evaluation. The selected responses were significantly affected by both variables (P < 0.05). The spreads resembled commercial peanut butter, both in appearance, texture and spreadability; were a source of ω-3 fatty acids and with no visual oil separation after 1 mo of storage. An optimum spread was produced using 1.25% (w/w) of stabilizer and 80% of hemp oil (w/w, of the total added oil) which had 0.97 g of ω-3 fatty acids per serving size; penetration depth of 68.4 mm; oil separation of 9.2% after 3 mo of storage; and a sensory score of 17.5. PRACTICAL APPLICATION A use of by-products generated from different food processing technologies, where the edible waste is successfully incorporated as a value-added ingredient, has become a very important area of research to support global sustainability efforts. This study contributes to the knowledge of a product design process for oil-based spread development, where oil press-cake, a by-product of the oil pressing process of the naked pumpkin seeds, was used and where results have demonstrated that a new product can be successfully developed and potentially manufactured as a functional food.

Valorization of Wet Okara, a Value-Added Functional Ingredient, in a Coconut-Based Baked Snack

ABSTRACT Wet okara (soy milk residue), as a functional ingredient, was evaluated to be added to a coconut-based snack at 10, 20, 30, 40, and 50% levels to replace dry coconut in the formula. Certain physicochemical, nutritional, and sensory properties of the samples were evaluated. A coconut-based, soft, baked snack with incorporated okara showed higher total fiber and much lower fat content than the control, which significantly improved the nutritional profile of the samples. Samples 3 and 4 (which had 30 and 40% replacement of coconut with wet okara, respectively) received the highest overall sensory score (8.4), which was significantly higher than the score of a control sample (7.5). Sample 3 also had a significantly improved nutritional profile per serving size, such as an increased fiber content of 6.11 ± 0.04 g/100 g and a decreased fat content of 17.57 ± 0.02 g/100 g, and sample 4 had an increased fiber content of 6.19 ± 0.03 g/100 g and a decreased fat content of 15.64 ± 0.03 g/100 g compared with...

Optimization of Hull‐Less Pumpkin Seed Roasting Conditions Using Response Surface Methodology

Response surface methodology (RSM) was applied to optimize hull-less pumpkin seed roasting conditions before seed pressing to maximize the biochemical composition and antioxidant capacity of the virgin pumpkin oils obtained using a hydraulic press. Hull-less pumpkin seeds were roasted for various lengths of time (30 to 70 min) at various roasting temperatures (90 to 130 °C), resulting in 9 different oil samples, while the responses were phospholipids content, total phenols content, α- and γ-tocopherols, and antioxidative activity [by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical assay]. Mathematical models have shown that roasting conditions influenced all dependent variables at P < 0.05. The higher roasting temperatures had a significant effect (P < 0.05) on phospholipids, phenols, and α-tocopherols contents, while longer roasting time had a significant effect (P < 0.05) on γ-tocopherol content and antioxidant capacity, among the samples prepared under different roasting conditions. The optimum conditions for roasting the hull-less pumpkin seeds were 120 °C for duration of 49 min, which resulted in these oil concentrations: phospholipids 0.29%, total phenols 23.06 mg/kg, α-tocopherol 5.74 mg/100 g, γ-tocopherol 24.41 mg/100 g, and an antioxidative activity (EC(50)) of 27.18 mg oil/mg DPPH.

INFLUENCE OF IMPURITIES AND HULL CONTENT IN MATERIAL FOR PRESSING ON SENSORY QUALITY COLD-PRESSED SUNFLOWER OIL

This paper analyzes influence of different percentage of impurities and hull in the material for pressing on sensory quality (appearance, smell, taste, aroma and colour) of edible nonrefined sunflower oil. It has been concluded that simultaneous presence of impurities and hull in the starting material, especially presence of bigger quantities of impurities, has a rather negative effect on sensory quality of sunflower oil, made by cold pressing on a screw press. Apart from sensory analysis, the effect of impurities and hull on oil colour has also been identified by transparency determining, i.e. content of total pigments – carotenoids and chlorophyll. It has been concluded that presence of bigger quantities of impurities and hull cause the increase of content of both carotenoids and chlorophyll, and at the same time, decrease of transparency value in cold-pressed sunflower oil.