Food Technology
Yazdan Moradi; Mansoreh Ghaeni; Haleh Hadaegh
Abstract
Introduction
Seaweeds contain a high amount of protein, essential amino acids, vitamins, minerals, unsaturated fatty acids such as arachidonic acid, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), natural pigments, macro and micro nutrient compounds. Microalgae Spirulina (Spirulina ...
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Introduction
Seaweeds contain a high amount of protein, essential amino acids, vitamins, minerals, unsaturated fatty acids such as arachidonic acid, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), natural pigments, macro and micro nutrient compounds. Microalgae Spirulina (Spirulina platensis) is a species with high nutritional value. About 60% to 70% of the dry weight (Spirulina platensis) is protein, which has all the essential amino acids. This is a cyanobacterial microalga that is cultivated all over the world and used as a supplement in the human diet in the form of tablets, powder and cookies, bread, salad and soup. Several studies have been conducted in the field of investigating the effect of microalgae addition in food products. The purpose of the current research was to investigate the effect of this microalgae powder on sensory, physical, protein and iron properties of three different products of bulk bread, cake and layered sweets with different formulations.
Materials and Methods
Spirulina microalgae dry powder in 0.25%, 0.5%, 0.75%, 1% and 1.25% was added to the formula of three products: bulk bread, layered pastry, and cake. From each product, a sample without microalgae powder was also prepared and considered as a control. The treatments were evaluated in terms of sensory, color, texture, protein and iron content. Sensory evaluation was carried out by 30 panelists using 7 hedonic points to evaluate the color, flavor, texture, smell and overall acceptance. The color of the surface of the samples was done with a Minolta Chroma Meter (CR-300 Minolta Japan). The results calculated based on L* (whiteness/darkness), a*(redness/greenness) and b*(blueness/yellowness). Hardness of samples was measured with Texture Analyzer TA-XT2 (Stable Micro Systems, Surrey, England) and P/0.5 cylindrical probe (12.5 mm diameter) with 30 kg load cell. Protein of the samples was measured by Kjeldahl method and the amount of iron was measured according to the standard method of AOAC 999.11. All analyses were performed in three repetitions and one-way ANOVA and Tukey's test were used to compare the means.
Results and Discussion
The results showed that the behavior of spirulina microalgae in changing the characteristics of the three products is different, and this difference is especially significant in sensory characteristics. The addition of spirulina microalgae increased the amount of protein and iron in different treatments. This increase for protein in bread, cake and sweets was about 1, 0.6 and 1.2 percent, respectively. Also, the amount of iron in treatments containing microalgae in bread, cake, and layered sweets was 4, 5, and 3 mg/kg, respectively. Spirulina microalgae is basically known as an aquatic plant with high protein and iron. The microalgae used in this research contained a high amount of protein (67.97%) and 29.5 mg/100 grams of iron, so adding this microalga to the samples increased the amount of protein and iron. Sensory evaluation of the samples showed that all three products had an acceptable acceptance score. However, in comparison among the three products of bread, cake and layered sweets, bread had a lower score than the other two products. The instrumental analysis of L*, a*, b* color indices showed that the increase of spirulina caused green color in the treatments and this color change is more significant in the bread sample. Also, the results of texture analysis showed that the addition of spirulina reduces the hardness of samples containing spirulina. It can be concluded that spirulina microalgae can be used to improve texture, color, and also increase the amount of protein and iron in products.
Food Technology
Bahareh Nowruzi
Abstract
Introduction
Intelligent food packaging as a new technology can maintain the quality and safety of food during its shelf life. This technology uses indicators and sensors that are used in packaging and detects physiological changes in food (due to microbial and chemical degradation). These indicators ...
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Introduction
Intelligent food packaging as a new technology can maintain the quality and safety of food during its shelf life. This technology uses indicators and sensors that are used in packaging and detects physiological changes in food (due to microbial and chemical degradation). These indicators usually provide information that can be easily identified by the food distributor and the consumer. However, most of the markers currently used are non-renewable and non-degradable synthetic materials. Microalgae that live in both marine and freshwater are a versatile solution for building new biosensors to detect pollutants such as herbicides or heavy metals. These photosynthetic microorganisms are very sensitive to their environmental changes and allow the detection of pollutants. In the past few years, several studies have been conducted in relation to the development, evaluation and application of biosensors using natural compounds in smart food packaging, and some of them are reported and summarized in Table 2.
Materials and Methods
In these studies, examples are mainly focused on biosensors related to biopolymers, but some other synthetic polymers that are easily degraded have also been used as examples. In Table 2, it is also specified what the function and application of the sensor is and how it reacts to the loss of freshness of food. Most sensors are sensitive to the change in pH caused by the release of volatile nitrogen compounds, and this change is characterized by a colorimetric response. Sensors are usually placed in the space above the food container, avoiding direct contact with the food, but close enough to detect changes in the environment and respond to changes in food quality. When these biosensors are integrated with biopolymers, they are usually incorporated into the polymer structure, and the color change of the layers (film) indicates changes in food quality in the packed product. The collected information also clearly shows that extracts rich in chemical compounds of pigments that change color with pH and especially anthocyanins have been used in these biosensors. In addition, most studies of biosensors have been conducted on fish, meat, and seafood, which is probably because their quality degradation is an important economic loss and also because the pH of the surrounding environment is changed during the degradation process. , and this change is easily detected through pH-sensitive biosensors. Smart food packaging technology has made it possible to monitor food quality by incorporating markers, sensors and radio frequency identification (RFID) into packaging. The technology also allows producers and consumers to trace the history of a product through important points in the food supply chain.Interestingly, some compounds applied and tested in the sensor not only provide a pH-sensitive dye, but also have other bioactive properties, for example, antimicrobial properties, and its presence in the polymer matrix can also increase the storage activity of packaging materials.
Results and Discussion
This paper shows that microalgae can be used as biosensors to detect pollutants such as herbicides, heavy metals and volatile organic compounds. These biosensors are very sensitive and reproducible for physical or chemical analysis. One of the main advantages of these microalgal biosensors is that repeated measurements can be performed without extensive sample preparation. They can also be selective, for example chlorophyll fluorescence emitted from photosynthetic activity allows the detection of herbicides, while inhibition of alkaline phosphatase and esterase allows the determination of heavy metals and organophosphate insecticides. Recently, great progress has been made in the identification of genes and related pathways in microalgae, and powerful techniques for genetic engineering have been developed. Collectively, the progress achieved in these areas will rapidly increase our ability to genetically optimize the production of more sensitive microalgae-based biosensors.
