Dried strawberries as a high nutritional value fruit snack

Effect of Pulsed Electric Field Technology on the Composition and Bioactive Compounds of Black Soldier Fly Larvae Dried with Convective and Infrared-Convective Methods

In recent years, an increasing interest has been shown in alternative food sources. Many studies are focused on the use of insects. The aim of this study was to investigate the changes in the chemical and thermal properties of black soldier fly larvae influenced by the pulsed electric field (PEF) and convective (CD) or infrared-convective (IR-CD) drying techniques. Examinations of the basic chemical composition, properties of extracted fat (fatty acid composition, acid and peroxide values, and oxidative stability), total polyphenol content, antioxidant activity, allergen content, and thermogravimetric analysis (TGA) were performed. Generally, the results showed that dried black soldier fly larvae are a good source of protein and fat, up to 33% and 44%, respectively. The fat extracted from the dried insects consisted mainly of saturated fatty acids (above 75%), in particular lauric acid (C12:0). A good oxidative stability of the fat was also observed, especially from samples dried with the IR-CD method. The convective drying technique allowed for better preservation of protein content compared to samples dried with the IR-CD method. Nevertheless, samples treated with PEF were characterized by significantly lower protein content. The samples after PEF pretreatment, with an intensity of 20 and 40 kJ/kg and dried with the IR-CD method, were represented by a significantly higher total polyphenol content and antioxidant activity. Furthermore, in most cases, the convectively dried samples were characterized by a higher allergen content, both crustaceans and mollusks. Taking into account all of the investigated properties, it can be stated that the samples without treatment and those that were PEF-treated with an intensity of 40 kJ/kg and dried with the infrared-convective method (IR-CD) were the most rewarding from the nutritional point of view.

Development of electronic nose for detection of micro-mechanical damages in strawberries

A self-developed portable electronic nose and its classification model were designed to detect and differentiate minor mechanical damage to strawberries. The electronic nose utilises four metal oxide sensors and four electrochemical sensors specifically calibrated for strawberry detection. The selected strawberries were subjected to simulated damage using an H2Q-C air bath oscillator at varying speeds and then stored at 4°C to mimic real-life mechanical damage scenarios. Multiple feature extraction methods have been proposed and combined with Principal Component Analysis (PCA) dimensionality reduction for comparative modelling. Following validation with various models such as SVM, KNN, LDA, naive Bayes, and subspace ensemble, the Grid Search-optimised SVM (GS-SVM) method achieved the highest classification accuracy of 0.84 for assessing the degree of strawberry damage. Additionally, the Feature Extraction ensemble classifier achieved the highest classification accuracy (0.89 in determining the time interval of strawberry damage). This experiment demonstrated the feasibility of the self-developed electronic nose for detecting minor mechanical damage in strawberries.

Dried fruit intake causally protects against low back pain: A Mendelian randomization study

Background

Low back pain is the leading cause of years lived with disability worldwide. The aim of this study was to evaluate whether dried fruit intake causally protects against low back pain using two-sample Mendelian randomization (MR).

Methods

We obtained summary-level data for dried fruit intake (N = 421,764) from the IEU Open GWAS Project. Forty-one independent genetic variants proxied dried fruit intake. The corresponding data for low back pain were derived from the FinnGen project (13,178 cases and 164,682 controls; discovery data) and the Neale lab (5,423 cases and 355,771 controls; replication data). We conducted univariable and multivariable MR analyses.

Results

In the univariable MR analysis, the inverse variance weighted estimate showed that greater dried fruit intake was associated with decreased risk of low back pain [odds ratio (OR) = 0.435, 95% confidence interval (CI): 0.287-0.659, P = 8.657 × 10^-5]. Sensitivity analyses using the MR-Egger (OR = 0.078, 95% CI: 0.013-0.479, P = 0.009), maximum likelihood (OR = 0.433, 95% CI: 0.295-0.635, P = 1.801 × 10^-5), weighted median (OR = 0.561, 95% CI: 0.325-0.967, P = 0.038) and Mendelian Randomization Pleiotropy RESidual Sum and Outlier (MR-PRESSO) (OR = 0.454, 95% CI: 0.302-0.683, P = 4.535 × 10^-4) methods showed consistent results. No evidence of directional pleiotropy was identified according to the Egger intercept (intercept P-value = 0.065) or applying the MR-PRESSO method (global test P-value = 0.164). The replication analysis yielded similar results. The multivariable MR revealed that the inverse association between dried fruit intake and low back pain was consistent after adjustment for fresh fruit intake, body mass index, current tobacco smoking, alcohol intake frequency, total body bone mineral density, serum 25-hydroxyvitamin D levels, and vigorous physical activity.

Conclusion

This MR study provides evidence to support that dried fruit intake causally protects against low back pain.

Optimization of Conditions for a Freeze-Dried Restructured Strawberry Block by Adding Guar Gum, Pectin and Gelatin

With its high moisture content and tender texture, fresh strawberry is very susceptible to mechanical damage and microbial infection. Drying is one of the most frequently employed methods to extend its shelf life, and freeze-dried restructured strawberry block (FRSB) is an emerging popular food. Here, in order to enhance the quality of FRSB, edible gums of guar gum, pectin, and gelatin were added and the combination was optimized using response surface methodology (RSM) with chewiness, hardness, and organoleptic evaluations of the dried sample as the response indicators. The results showed that the combination addition of 0.10% guar gum, 0.22% pectin, and 0.30% gelatin contributed to the highest comprehensive quality of the dried sample. Compared with the untreated sample, the optimal combination addition of the three edible gums resulted in a higher moisture content for the dried sample (increased by 0.8%), and increased the chewiness, hardness, and porosity by 82.04%, 27.09%, and 3.01%, respectively, while maintaining more original color and forming a denser porous microstructure. The findings in the current work will be useful for the application of edible gums in freeze-dried restructured fruits and vegetables.

Influence of Pretreatments and Freeze-Drying Conditions of Strawberries on Drying Kinetics and Physicochemical Properties

The aim of this study is to analyze the effects of pretreatments and drying temperature on the freeze-drying (FD) kinetics, ascorbic acid content, color changes, and antioxidant activity (AA) of strawberries. Experiments were performed at 20 °C, 40 °C, and 60 °C, with a constant pressure of 63 Pa in the FD chamber. The strawberry samples were cut into slices (CS) and pulped (PS) before drying. The drying kinetics was best described using the Midilli or logistic model depending on the strawberry grinding method used and the FD temperature. The FD of strawberries significantly increased the lightness, redness, and yellowness of the dried fruit. The FD temperature and pretreatment methods had little influence on the total phenolic content (TPC) and AA. The lowest TPC was found in strawberry pulps after dehydration at 60 °C, and the highest TPC was observed in strawberry slices dehydrated at the same temperature (18.54 and 22.04 mg of gallic acid equivalent per gram of dry mass, respectively). Furthermore, the ascorbic acid content in dried strawberries was higher for the samples freeze-dried at a higher temperature.

Current Applications of Ultrasound in Fruit and Vegetables Osmotic Dehydration Processes

Ultrasound (US) is a promising technology, which can be used to improve the efficacy of the processes in food technology and the quality of final product. US technique is used, e.g., to support mass and heat transfer processes, such as osmotic dehydration, drying and freezing, as well as extraction, crystallization, emulsification, filtration, etc. Osmotic dehydration (OD) is a well-known process applied in food processing; however, improvements are required due to the long duration of the process. Therefore, many recent studies focus on the development of OD combined with sonication as a pretreatment method and support during the OD process. The article describes the mechanism of the OD process as well as those of US and changes in microstructure caused by sonication. Furthermore, it focuses on current applications of US in fruits and vegetables OD processes, comparison of ultrasound-assisted osmotic dehydration to sonication treatment and synergic effect of US and other innovative technics/treatments in OD (such as innovative osmotic solutions, blanching, pulsed electric field, reduced pressure and edible coatings). Additionally, the physical and functional properties of tissue subjected to ultrasound pretreatment before OD as well as ultrasound-assisted osmotic dehydration are described.

Co-ingested vinegar-soaked or preloaded dried apple mitigated acute postprandial glycemia of rice meal in healthy subjects under equicarbohydrate conditions

This study investigated 2 possible approaches to dietary control of acute postprandial responses to a rice-based meal under equicarbohydrate conditions: (1) a dried apple (DA) preload and (2) co-ingestion of vinegar-soaked DA. We hypothesized that both approaches would counteract hyperglycemia with no negative effect on satiety, possibly explained by an inhibitory effect on digestive enzyme activity and/or the effect of the sugar component of the DA. Fifteen healthy female subjects consumed (1) rice, (2) co-ingestion of DA and rice (DA + R), (3) DA preload and rice (PDA + R), (4) rice with sugar solution (same sugar profile as in DA) preloaded (PSS + R), or (5) co-ingestion of rice with vinegar-soaked DA (VDA + R) in a randomized crossover trial. Acute postprandial glycemic response tests and subjective satiety tests were conducted for each test meal. Compared with rice reference, the PA + R and PSS + R achieved 31.4% and 36.3% reduction of the incremental area under the curve_0-120, 24.3% and 27.0% decreases in the average glucose peak, along with 21.6% and 27.0% decreases in glycemic excursion in 240 minutes, whereas the VDA + R resulted 42.4%, 27.0%, and 29.7% reductions in the incremental area under the curve_0-120, peak, and glycemic excursion, respectively. The DA-containing meals had no effect or a favorable effect on satiety. The in vitro assay found larger resistant starch and smaller rapid digestible starch fractions in DA + R and VDA + R meals compared to those of the rice reference (P < .001). The result of this study supported the research hypothesis, and the DA-containing meals could be considered as a potential dietary approach for glycemic management.

Classification of Dried Strawberry by the Analysis of the Acoustic Sound with Artificial Neural Networks

In this paper, the authors used an acoustic wave acting as a disturbance (acoustic vibration), which travelled in all directions on the whole surface of a dried strawberry fruit in its specified area. The area of space in which the acoustic wave occurs is defined as the acoustic field. When the vibrating surface—for example, the surface of the belt—becomes the source, then one can observe the travelling of surface waves. For any shape of the surface of the dried strawberry fruit, the signal of travelling waves takes the form that is imposed by this irregular surface. The aim of this work was to research the effectiveness of recognizing the two trials in the process of convection drying on the basis of the acoustic signal backed up by neural networks. The input variables determined descriptors such as frequency (Hz) and the level of luminosity (dB). During the research, the degree of crispiness relative to the degree of maturity was compared. The results showed that the optimal neural model in respect of the lowest value of the root mean square turned out to be the Multi-Layer Perceptron network with the technique of dropping single fruits into water (data included in the learning data set Z2). The results confirm that the choice of method can have an influence on the effectives of recognizing dried strawberry fruits, and also this can be a basis for creating an effective and fast analysis tool which is capable of analyzing the degree of ripeness of fruits including their crispness in the industrial process of drying fruits.

The Use of a Hybrid Drying Method with Pre-Osmotic Treatment in Strawberry Bio-Snack Technology

The aim of this study was to determine the effect of osmotic pre-treatment on physical and sensory properties of dried strawberry. Frozen strawberries were dehydrated in sucrose solution with/without 5 or 15 % concentrated chokeberry juice. Then, samples were dried in hybrid (convective-microwave-vacuum) and freeze-drying method. The chokeberry juice concentrate addition to the osmotic solutions had no effect on the mass transfer of dehydrated strawberries but changes in sensory properties, also after storage. Initial osmotic treatment in sucrose solution with 5 % of chokeberry juice concentrate resulted in improved colour, when 15 % addition caused the darkening of the dried strawberries. Strawberries dried by hybrid method exhibited greater hardness and brittleness than by freeze-drying, which were slightly higher evaluated in the sensory analysis. Storage for 3 months resulted in an increase in the hardness of the samples, the reduction of colour parameters and sensory quality.

Potato snacks added with active components: effects of the vacuum impregnation and drying processes

Potato snacks can be used as an ideal strategy for nutrient delivery, since they are one of the most widely consumed products in the world. Due to fried snacks are known to be a significant source of fat intake, consumption is changing towards healthier alternatives. The aim of this research is to evaluate the effect of vacuum impregnation and three dehydration techniques: heated air drying, freeze drying, and microwave vacuum drying of the potato snack that has been fortified with active components: calcium and vitamins C and E. Vacuum impregnation was evaluated using the response surface methodology that had a central composite experimental design with the following independent variables: vacuum pressure, vacuum stage time, and atmospheric stage time. The following were the dependent variables: fraction and volumetric deformation in the vacuum stage and at the end of the process and effective porosity. Finally, a sensorial analysis was carried out on the dehydrated potatoes. The results of the optimal vacuum impregnation process conditions were: a vacuum pressure of 77.3 kPa for 3.0 min followed by 4.0 min at atmospheric pressure. The content of calcium, vitamin C, and vitamin E in the impregnated potato were 956, 472, and 35 mg 100 g^-1 dry solids, respectively. The highest retention of the active components in snacks was obtained by the combination of vacuum impregnation and the dehydration techniques in the following order: freeze drying, microwave vacuum drying, and then heated air drying. It can be concluded that the integration processes give an added value to potato snacks due to the increased content of the active components; additionally, the vacuum impregnation process together with microwave vacuum drying was the alternative that had the highest sensorial acceptability.

Apple juice concentrate impregnation enhances nutritional and textural attributes of the instant controlled pressure drop (DIC)-dried carrot chips

BACKGROUND

Osmotic pretreatment is an effective processing unit for improving the textural quality of dried fruit and vegetable snacks, whereas nutrition loss and high calorie after impregnation is still a noteworthy shortcoming of sugar-immersed products. Therefore, the use of apple juice concentrate as a clean label solution to improve the qualities of instant controlled pressure drop (DIC)-dried carrot chips was investigated.

RESULTS

Apple juice concentrate impregnation substantially enhanced the physical properties of the carrot chips, including hardness (38.28 N), crispness (2.01 mm), porosity (66.72%) and homogeneous microstructure, comparable to chips obtained using sucrose and maltiltol based osmotic solutions. Additionally, compared to the sucrose and maltiltol impregnated chips, a higher retention of carotenoids (302.81 μg g^-1 , dry basis), a higher multiplicity of phenolic compounds, stronger antioxidant activities and a superior sensory score were observed in the chips pretreated with apple juice concentrate.

CONCLUSION

Apple juice concentrate could be used as a clean label osmotic solution to enhance the organoleptic attributes and fortify the nutritional properties of DIC-dried carrot snacks. © 2019 Society of Chemical Industry.