The Effect of Spirulina Algae Enrichment on the Quality of Pistachio Butter

Pistachio butter is one of the pasty products made from pistachio kernels. This study investigated color characteristics, peroxide value, fat, protein, and carbohydrate content, and sensory evaluation of pistachio butter enriched with Spirulina algae (0, 5, and 10%) during three months of storage at 20°C. With increasing the percentage of the algae, the sample with 10% of the algae showed the highest protein content (around 25.4%). The highest and lowest fat content was observed in the control and the sample containing 10% algae, respectively. The lowest peroxide value (0.73 meq kg-1) was observed in the sample containing 10% algae compared to others. The level of carbohydrates did not change significantly in all three specimens during storage. Sensory evaluation for taste, sweetness, color, spreadability, mouthfeel, and texture showed that the sample without algae and the specimen containing 5% algae did not differ much. With increasing the algae level to 10%, the sensory evaluation had a significant drop, and in some cases, there was a decrease in the score. The color evaluation of the samples showed that with increasing the algae level, the greenness of the specimen increased, a value decreased, and b value did not show a significant change. Overall, The amount of algae recommended in the pistachio butter formulation is 5%

Effect of roasting conditions on hardness, moisture content and colour of pistachio kernels

Roasting of whole-kernels is an important step in the production of pistachio paste. The effect of hot air roasting temperatures (90-190°C) and times (5-65 min) on the hardness, moisture content and colour attributes ('L', 'a' and 'b' values and yellowness index) of both whole-kernel and ground-state were investigated using response surface methodology (RSM). Increases in roasting temperature and time caused a decrease in all the responses except for 'a' value of ground-state. The interaction and quadratic models sufficiently described the changes in the hardness and colour values, respectively. The result of RSM analysis showed that hardness and colour attributes ('L' and 'b' values, yellowness index) of kernels and 'a' value of ground-state could be used to monitor the roasting quality of whole-kernels. This study showed that the recommended range of roasting temperature and time of whole-kernel for the production of pistachio paste were 130-140°C and 30-40 min, respectively

Development of pistachio (pistacia vera L.) spread.

Pistachio nut (Pistacia vera L.) is one of the most delicious and nutritious nuts in the world. Pistachio spreads were developed using pistachio paste as the main component, icing sugar, soy protein isolate (SPI), and red palm oil (RPO), at different ratios. The highest mean scores of all the sensory attributes were depicted by spreads that were made without addition of SPI. It was found that the work of shear was 0 to 11.0 kg s for an acceptable spread. Sensory spreadability, overall texture, spreadability, and overall acceptability were negatively correlated (R > 0.83) with the work of shear of spreads. The findings indicated that the presence of RPO had a direct effect on the viscoelastic behavior of the pistachio spreads. The a values, which are related to the green color of the pistachio product ranged from 1.7 to 3.9 for spread without addition of RPO, and 4.0 to 5.3 in the presence of RPO

Textural, Rheological and Sensory Properties and Oxidative Stability of Nut Spreads-A Review.

Tree nuts are rich in macro and micronutrients, phytochemicals, tocopherols and phenolic compounds. The development of nut spreads would potentially increase the food uses of nuts and introduce consumers with a healthier, non-animal breakfast snack food. Nut spreads are spreadable products made from nuts that are ground into paste. Roasting and milling (particle size reduction) are two important stages for the production of nut spreads that affected the textural, rheological characteristic and overall quality of the nut spread. Textural, color, and flavor properties of nut spreads play a major role in consumer appeal, buying decisions and eventual consumption. Stability of nut spreads is influenced by its particle size. Proper combination of ingredients (nut paste, sweetener, vegetable oil and protein sources) is also required to ensure a stable nut spread product is produced. Most of the nut spreads behaved like a non-Newtonian pseudo-plastic fluid under yield stress which help the producers how to start pumping and stirring of the nut spreads. Similar to other high oil content products, nut spreads are susceptible to autoxidation. Their oxidation can be controlled by application of antioxidants, using processing techniques that minimize tocopherol and other natural antioxidant losses

The effect of monoglyceride addition on the rheological properties of pistachio spread

Pistachio nut (Pistacia vera L.) is one of the most delicious and nutritious nuts in the world. In this study, monoglycerides (0.0–1.5 %) as lipophilic emulsifiers were used to prevent oil separation in pistachio spread A (containing 50.0 % pistachio paste, 30.0 % icing sugar and 20.0 % red palm oil) and B (containing 58.3 % pistachio paste, 25.0 % icing sugar and 16.7 % red palm oil). Changes in rheological behavior of pistachio spreads were investigated. The highest work of shear (which indicates spreadability) was observed in Formulations A and B containing 1.5 % monoglycerides. Addition of emulsifier significantly (P < 0.05) influenced the consistency index (K), thixotropic area (A), yield stress (τ 0) and coefficient correlation (R) of pistachio spreads. All the pistachio spreads that contained emulsifier exhibited a higher storage modulus (G′) than the loss modulus (G″)

Effect of Freezing and Vacuum Packaging on Quality Properties of Pistachio Powder During Storage

Pistachio powder is a product used today in confectionery, ice cream, pistachio paste and other foods. Considering the higher rate of spoilage and oxidation in pistachio powder, developing methods to increase the shelf-life of this product is therefore important. In this study the effect of  freezing and vacuum packaging on the quality characteristics of pistachio powder during storage was investigated. The effect of packaging conditions (vacuum or air packaging), storage temperature (25°C, -18°C) and storage time (0, 1, 2, 3 and 4 months) on chemical (free fatty acids, acid value, peroxide value), physical (moisture content and color indexes of L*, a* and b*), and sensory (odor, taste, color, texture and overall acceptance) characteristics were studied. The results revealed that the peroxide value, acid value and free fatty acids in frozen and vacuum containers were lower than those packed without vacuum at room temperature. The results of sensory evaluation indicated a significant difference (p< 0.05) in samples.The best quality characteristics in terms of odor, taste, and overall acceptance belonged to the pistachio powder packed in vacuum and frozen conditions; however, in terms of texture , the containers packed and stored in ambient conditions showed better results. In all cases, the quality of pistachio powder decreased during the storage period. There was no significant difference between samples in moisture content, color indices of L*, a*, b* and sensory evaluation of color. It was generally found that packaging under vacuum and freezing could increase the shelf life of pistachio powder

Types of dryers and their effect on the pistachio nuts quality - A Review.

This review discusses the performance of existing dryers for pistachio drying process, which is available in the literature. It encompasses sun drying, solar dryer, bin dryer, vertical continuous dryer, funnel cylindrical dryer, vertical cylindrical dryer, continuous mobile and steady tray dryer, drum dryer and continuous belt conveyor dryer. The split nut and shell appearance of pistachio nuts are significantly influenced by the drying methods. The types of dryer used for drying pistachio nuts are critical to the final quality of the product. Although sun drying has a good effect on the final product quality, the negative climatic and environmental conditions must be considered. A combination of bin dryer and sun drying or combination of bin dryer and solar dryer, are recommended as effective drying techniques to prevent adverse quality effect on pistachio nut

Development and oxidative stability of pistachio (Pistacia vera L.) spread

Pistachio nut (Pistacia vera L.) is one of the popular tree nuts in the world. Due to its high nutritional value, pistachio is an increasingly important nut consumed either in the form of raw, roasted or salted. The main objective of this study was to value-add pistachio nut (Ohadi variety) by conversion into an acceptable and shelf-stable pistachio spread. Specifically, this study was conducted to investigate the effect of processing conditions of pistachio kernels (roasting and milling) on the quality of pistachio paste, to develop pistachio spread as a new product, and to determine the physicochemical properties and oxidative stability of pistachio spread. In the first part of the study, results obtained showed that increases in roasting temperature and time caused a decrease in the color attributes of both whole kernels and ground kernels except for the a value of ground kernels. The hardness (N) and color attributes (L value, b value and yellowness index) of whole kernels and the 'a' value of ground kernels could be used to monitor the roasting quality of whole kernels. The recommended range of roasting temperature and time of whole kernels for the production of pistachio paste were 130-140°C and 30-40 min, respectively. The colloidal stability of pistachio paste samples was found to be influenced by particle size and the most stable pistachio paste was obtained when the mill gap size was 20 μm. All pistachio pastes under study depicted the pseudo-plastic and thixotropic behaviors. The Herschel-Bulkley model was the most appropriate model to describe the flow behavior of pistachio paste. The storage modulus (G') values of pistachio paste were higher than the loss modulus (G'') values for all frequencies studied. The second part of this study concentrated on the development of pistachio spread from the pistachio paste. The spread was prepared using pistachio paste as the main component, icing sugar, soy protein isolate and red palm oil at different ratios. A total of 17 formulations were prepared. From the study, two formulations were selected based on their sensory properties, work of shear, color attributes, oil stability, flow behavior and dynamic oscillatory property. The two formulations were Formulation 12 which contained 50.0% pistachio paste, 30.0% icing sugar, and 20.0% red palm oil, and Formulation 16 which comprised of 58.3% pistachio paste,25.0% icing sugar and 16.7% red palm oil. Following this, appropriate terminologies for describing the sensory characteristics of these pistachio spreads were developed using quantitative descriptive analysis (QDA). Thirty-two potential panelists were screened and only twelve panelists were selected for training and finally only eight of them were found to be qualified for the evaluation of pistachio spread. Twenty attributes in terms of appearance, aroma, flavor, texture and aftertaste of pistachio spread were identified and developed by the trained panelists. Results from sensory evaluation showed that no significant (P < 0.05) difference was observed in all the sensory attributes between the selected pistachio spread formulations except for sweetness. In the third part of this study, further improvement of the pistachio spread, especially with respect to prevent oil separation, was made by the addition of monoglycerides (Dimodan HP-M). Results showed that the addition of 0.75 and 1.5% of monoglycerides led to the reduction in oil separation during storage probably due to creation of a strong network between fat, protein and other component by the emulsifier. The addition of monoglycerides also influenced the rheological characteristics such as the flow behavior (K, n, A, τ0 and R), dynamic oscillatory values (Gʹ, Gʹʹ and tan δ) and color of the spread. The most suitable formulation based on the observed physicochemical, physical and rheological studies was the one that contained 58.3% pistachio paste, 25.0% icing sugar, 15.2% red palm oil and 1.5% monoglycerides. Based on the results obtained on the effect of accelerated storage at 60oC, it can be concluded that the shelf life of pistachio spread was 320 days at 20 ± 2°C

Effects of early harvest times on nut quality and physiological characteristics of pistachio (Pistacia vera) trees

Introduction - Pistachio harvesting at the appropriate time is one of the key factors affecting the product quality. The effects of early harvest time on quantitative and qualitative properties of pistachio nuts were investigated. Materials and methods - The 'Ohadi' pistachio cultivar was used as the market reference in Iran. Five harvest times (July 27, August 6, August 16, August 27 and September 6) were studied over four consecutive years (2008-2011) as treatments in the field experiment. Nut weight parameters, hull discoloration, hulling, cracked nuts, early-split nuts, kernel protein, mineral and chlorophyll contents were evaluated at each harvest time. Results and discussion - The fresh and dry nut weights showed the maximum and the minimum nut production rates for the last (September 6) and the first (July 27) harvest times, respectively. Percentages of hull discoloration, cracked nuts and immature nuts were significantly influenced by harvest time. The early-split nut percentage was not significantly different at the various harvest times. The maximum potassium, calcium, magnesium and nitrogen, protein and chlorophyll contents were obtained at the first harvest time. The growth of current year shoots, leaf area, percentages of vegetative and reproductive buds were not influenced by the harvest time, whereas the abscission of reproductive buds was minimum at the first harvest time and significantly different from all other times. Conclusion - Early harvesting of pistachio is preferable in terms of crop health indicators, nutritional value and color of the kernels. However, it is not preferable in terms of yield (nut and kernel production per hectare) for the producers, although potentially more sustainable

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