ACOUSTIC ENVELOPE DETECTOR FOR CRISPNESS ASSESSMENT OF BISCUITS

Texture Analysis of Chinese Dried Noodles during Drying Based on Acoustic-Mechanical Detection Methods

To better understand the textural transformation of Chinese dried noodles during the drying process, a convenient acoustic-force detection method was established. By comparing the breaking point, it was possible to determine the time-scale correlation between the force-displacement curves and acoustic spectrograms. The acoustic eigenvalues showed a consistent upward trend with the mechanical parameters during the drying process. With a wave crest reaching 152.8 dB and a signal maximum reaching 0.072, the structural stability of the dried noodles hardly induces a higher acoustic response. This suggests that the mechanical strength and rigidity of the dried noodles undergo minimal changes during this period. In comparison to the mechanical parameters, the acoustic eigenvalues accurately describe the changes in texture of dried noodles under various drying conditions, moreover, the sound threshold also provides a more effective response to the dried noodles' structural strength threshold. Therefore, the acoustic detection method can be applied to assist the conventional mechanical measurement in the field of the texture evaluation of dried food.

Influence of Infill Level and Post-Processing on Physical Parameters and Betaine Content of Enriched 3D-Printed Sweet Snacks

Betaine is a non-essential amino acid with proven functional properties and untapped potential for cereal food enrichment. While 3D printing represents a viable approach for manufacturing enriched cereal-based foods with novel shapes and textures, it is crucial to consider the impact of printing parameters and post-processing on the betaine content and properties of these products. The aim of this study was to investigate the influence of the infill level (20, 30 and 40%) of 3D-printed cuboid shapes and the post-processing techniques (drying oven, vacuum dryer, air fryer) of betaine-enriched oat-based snacks on the print quality, texture, and sensory properties, as well as the content of preserved betaine. The interaction of post-processing technique and infill level influenced the length deviation and texture properties, as well as the betaine content of snacks. Height stability was only influenced by post-processing technique. In general, oven-dried snacks showed the best dimensional stability, having the lowest width/length deformation (about 8%) at the infill level of 20%. Betaine was best preserved (19-31% loss) in snacks post-processed in a vacuum dryer (1281-1497 mg/g), followed by an air fryer and a drying oven, where betaine loss was in the range 28-55%. Air-fried snacks with 40% infill level had the highest values of instrumentally measured crunchiness (38.9 Nmm) as well as sensory test values for liking of texture (7.5), intensity of odor (6) and overall flavor (6). Overall, air frying proved to be a convenient and quick post-processing technique for 3D-printed snacks, but infill patterns for preserving betaine should be further explored. Vacuum drying could be used to preserve bioactive compounds, but efforts should be made to minimize its negative impact on the physical deformations of the 3D-printed products.

Mechanical approach for the evaluation of the crispiness of food granular products

Crispiness of food products is a key parameter for consumer acceptance. Available methods to evaluate this attribute are subjective and have limitations. They are particularly difficult to implement when granular products are considered. The present study aims to provide a physical characterization of the crispiness of food granular products (gari and grinded corn flakes) based on the compression cycle modeling and the determination of the Py (yield pressure) parameter of the Heckel model. High Py values attributed to the brittle behavior, are indicative of product crispiness. Furthermore, Py parameter showed sensitivity to the plasticizing effect of water. This developed physical method was validated through sensory analysis and acoustic measurements which are both considered as reference methods for crispiness evaluation. The brittle/plastic behavior attributed to crispy/non crispy products respectively was confirmed through image analysis using X-ray microcomputed tomography. The latter made it possible to distinguish the brittle from the plastic behavior through the particle size distribution evolution. This work suggests that the Py value is a relevant indicator for the crispiness evaluation of granular products. This physical characterization is expected to contribute in food engineering as an alternative method for granular products crispiness in a simpler and a more objective way.

Rational Food Design Targeting Micronutrient Deficiencies in Adolescents: Nutritional, Acoustic-Mechanical and Sensory Properties of Chickpea-Rice Biscuits

"Hidden hunger", the deficiency of important mineral micronutrients, affects more than 2 billion people globally. Adolescence is unquestionably a period of nutritional risk, given the high nutritional requirements for growth and development, erratic or capricious diets and the increased consumption of snacks. This study applied the rational food design approach to obtain micronutrient-dense biscuits by combining chickpea and rice flours to achieve an optimal nutritional profile, crunchy texture and appealing flavour. The perception of 33 adolescents regarding the suitability of such biscuits as a mid-morning snack was examined. Four biscuits were formulated, with different ratios of chickpea and rice flours (CF:RF): G100:0, G75:25, G50:50 and G25:75. Nutritional content, baking loss, acoustic-texture and sensory analyses were carried out. On average, the mineral content of biscuits with the CF:RF ratio of 100:0 doubled compared with the 25:75 formula. The dietary reference values for iron, potassium and zinc reached 100% in the biscuits with CF:RF ratios of 50:50, 75:25 and 100:0, respectively. The analysis of mechanical properties revealed that samples G100:0 and G75:25 were harder than the others. Sample G100:0 showed the highest sound pressure level (Smax). Sensory analysis showed that increasing the proportion of CF in the formulation augments the grittiness, hardness, chewiness and crunchiness. Most of the adolescents (72.7%) were habitual snack consumers; 52% awarded scores ≥ 6 (out of 9) to biscuit G50:50 for its overall quality, 24% described its flavour as "biscuit" and 12% as "nutty". However, 55% of the participants could not pinpoint any dominant flavour. In conclusion, it is possible to design nutrient-dense snacks that meet the micronutrient requirements and sensory expectations of adolescents by combining flours naturally rich in micronutrients.

The Effect of Pretreatments on the Physical Properties and Starch Structure of Potato Chips Dried by Microwaves under Vacuum

Native potato starch has a semi-crystalline structure associated with a low glycemic index. Microwave vacuum drying (MWVD) produces crispy snacks under mild temperatures, reducing starch structural changes. However, blanching pretreatment gelatinizes starch, reducing crystallinity. A promising alternative is drying raw or blanched-then-cooled potatoes by MWVD. Cooling the blanched potato before MWVD aims to promote the partial return of the crystalline structure. Thus, this study evaluated how different pretreatments affect potato chips’ starch structure and physical properties. Three samples were dried by MWVD: (i) raw (MWVD-RW), (ii) blanched (MWVD-BL), and (iii) blanched followed by cooling (4 °C for 48 h) (MWVD-BLC) potatoes. MWVD-RW samples presented a higher starch crystallinity (16.9%), which disappeared in MWVD-BL samples and partially returned in MWVD-BLC (8.7%). MWVD-BL and MWVD-BLC samples presented lower bulk (<0.338 g cm−3) density and higher porosity (>74%) and crispness. On the other hand, MWVD-BLC samples presented intermediate characteristics for color, true density, and porous distribution compared to others. All samples showed high porosity (>69%) and crispy texture. Therefore, based on the quality assessment, the MWVD-RW and MWVD-BLC produced healthy and crispy oil-free chips with a potentially lower glycemic index.

Children's acceptability profiles for biscuits with different fibre content

Due to the widespread rejection by children of products with high-fibre content, new approaches to meet the dietary recommendations on fibre intake are necessary. To understand which sensory properties influence this rejection, children's acceptability was examined in high-fibre biscuits and drivers of liking were identified. One hundred and ten Spanish children (6-12 years old) evaluated the overall liking of eight commercial biscuits with variable fibre content and stated their preference. To study the drivers of liking, the samples were characterised through a quantitative descriptive analysis, the determination of the moisture and water activity as well as the instrumental evaluation of texture with a texture analyser. It was suggested that the addition of fibre in biscuits reduced children's liking ratings. High-fibre samples were sensory and instrumentally described as harder, crispier and more chewing than the samples with medium and low fibre content. The main sensory driver of liking identified in this study was the soft texture. Despite their hard texture, high- and medium-fibre samples were chosen as the preferred ones for 14% of the children that participated when they included chocolate taste. Drivers of disliking identified in this study were related to the addition of fruit as a filling or as dehydrated pieces. This knowledge about children's acceptability of high-fibre products might be of interest for the food industry with the aim of developing well-accepted products that supply nutritional deficiencies associated with the fibre intake.

Impact of freeze-drying conditions on the sensory perception of a freeze-dried orange snack

BACKGROUND

The health benefits provided by fruit mean that there is continuous interest in offering consumers new products to stimulate its consumption. To this end, dehydrated fruit snacks may be an interesting option. In this study, we evaluated the impact of freezing rate (slow and high), shelf temperature (40 and 50 °C), and working pressure (5 and 100 Pa) on the perception and acceptability of a freeze-dried orange snack obtained from an orange puree.

RESULTS

Of the different freeze-drying conditions studied, working pressure was the variable with the greatest effect. The lowest working pressure (5 Pa) led to samples being obtained with a slightly lower water content, which was perceived with higher citrus flavor and crispiest. The highest pressure (100 Pa) led to samples with a greater water content, perceived with a more yellow intense color. Nevertheless, there is no significant consumer preference for any of the different processed samples. The number of force peaks, which is positively correlated with the crispness, shows a significant and negative correlation (r = -0.91) with the water content of the sample.

CONCLUSION

The study revealed that considerations other than the sensory can determine the best conditions of the freeze-drying process with which to obtain an orange snack. The number of force peaks obtained from a penetration test may be proposed as a tool for instrumental analysis of the snack's crispness that supplies information closely resembling customer perception of this attribute. © 2021 Society of Chemical Industry.

Development of a separated-dough method and flour/starch replacement in gluten free crackers by cellulose and fibrillated cellulose

Two strategies were combined and applied in this study to achieve a desired structure and texture of gluten free crackers and to reduce the calorie content. The first strategy is increasing structural heterogeneity of crackers and doughs and a separated-dough method was developed. A butter dough and a water dough were prepared separately and mixed together and the influence of mixing time was investigated. In the second strategy, which is the incorporation of a structuring material, powdered cellulose and fibrillated cellulose were incorporated in formulation to replace flour and pregelatinised starch with enhanced health benefits of low calorie and high fibre. Powdered cellulose played the role of the skeleton of the gluten free crackers. A laminar structure was observed in crackers when powdered cellulose was initially added to the butter dough. The crackers exhibit high thickness, hardness and fracturability and sharp sound emission which are typically observed in wheat crackers. Pregelatinised starch can be replaced by fibrillated cellulose at a lower addition level.

A Magnetic Food Texture Sensor and Comparison of the Measurement Data of Chicken Nuggets

Food texture is one of the important quality indicators in foodstuffs, along with appearance and flavor, contributing to taste and odor. This study proposes a novel magnetic food texture sensor that corresponds to the tactile sensory capacity of the human tooth. The sensor primarily consists of a probe, linear slider, spring, and circuit board. The probe has a cylindrical shape and includes a permanent magnet. Both sides of the spring are fixed to the probe and circuit board. The linear slider enables the smooth, single-axis motion of the probe during food compression. Two magnetoresistive elements and one inductor on the circuit board measured the probe’s motion. A measurement system then translates the measurement data collected by the magnetoresistive elements into compression force by means of a calibration equation. Fundamental experiments were performed to evaluate the range, resolution, repetitive durability of force, and differences in the frequency responses. Furthermore, the sensor was used to measure seven types of chicken nuggets with different coatings. The difference between the force and vibration measurement data is revealed on the basis of the discrimination rate of the nuggets.

Effects of psyllium seed husk powder, methylcellulose, pregelatinised starch, and cold water swelling starch on the production of gluten free crackers

Psyllium seed husk powder and pregelatinised starch crackers had comparable textural properties and sound release to wheat crackers, while the functionality of methylcellulose was limited due to low moisture addition.

Quick assessment of the potato chip crispness using the mechanical-acoustic measurement method

Traditional assessment method for the food crispness was sensory analysis which was time consuming and needed experienced panelists. Aiming to to develop a quick evaluation of the food crispness, a mechanical-acoustic testing method was proposed where two parameters-maximum force (Fmax) and maximum acoustic energy in unit time (SEmax) were applied to assess the crispness of dried potato chips. It was found the mechanical-acoustic testing was completed in about 1.2 s and the potato chips had a statistic distributions for Fmax and SEmax. The brand A potato chips had a statistic average Fmax of 13.48 N and SEmax of 93.51 mV·ms. Three kinds of potato chips can be effectively differentiated according to the statistic average SEmax and Fmax. Sensory “crispness” had a good correlation with the statistic average SEmax. This work shows that it is feasible for a quick measurement of the food crispness using this mechanical-acoustic method.

Measurement of vertical and horizontal vibrations of a probe for acoustic evaluation of food texture

Two-dimensional (vertical and horizontal) vibrations of a wedge-type probe upon food rupture were evaluated separately using two accelerometers placed perpendicular to a guide rod of a swing-arm device for texture evaluation of the flesh of three varieties of apples and three types of potato chips. Voltage signals from the accelerometers were filtered using a half-octave band-pass filter. The energy texture index (ETI), based on kinetic energy of the vertical or horizontal probe vibrations, was calculated over low to high frequency bands (no. 1-21). The spectra for the flesh of the three varieties of apples included two common peaks for vertical ETI at band no. 11 (1,120-1,600 Hz) and 19 (17,920-25,600 Hz) and horizontal ETI at band no. 1 (0-10 Hz) and 15 (4,480-6,400 Hz). The spectra for the three types of potato chips had a common ETI peak at band no. 11 (1,120-1,600 Hz) for horizontal ETI and at no. 15 (4,480-6,400 Hz) for vertical ETI. The three apple varieties gave rise to different intensities of vertical and horizontal ETIs while the two peaks were maintained. The thick potato chip type had higher vertical and horizontal ETIs than the thin and soft varieties in most bands; however, the thin type had the highest vertical ETIs only in lower bands (0-200 Hz). The soft type had the lowest vertical and horizontal ETI. The above results suggest that different food textures can be distinguished by two-dimensional vibration analyses of probe insertion into a food sample based on frequency bands.

Analysis of pectin biopolymer phase states using acoustic emissions

Acoustic emissions are stress or elastic waves produced by a material under external load. Since acoustic emissions are generated from within and transmitted through the substance, the acoustic signature provides insights into the physical and mechanical properties of the material. In this report, we used a constant velocity probe with force and acoustic emission monitoring to investigate the properties of glass phase and gel phase pectin films. In the gel phase films, a constant velocity uniaxial load produced periodic premonitory acoustic emissions with coincident force variations (saw-tooth pattern). SEM images of the gel phase microarchitecture indicated the presence of slip planes. In contrast, the glass phase films demonstrated early acoustic emissions, but effectively no force or acoustic evidence of periodic or premonitory emissions. Microstructural imaging of the glass phase films indicated the presence of early microcracks as well as dense polymerization of the pectin (without evidence of slip planes). We conclude that the water content in the pectin films contributes to not only the physical properties of the films, but also the stick-slip motion observed with constant uniaxial load. Further, acoustic emissions provide a sensitive and practical measure of this mechanical behavior.

Spectrum crispness sensory scale correlation with instrumental acoustic high-sampling rate and mechanical analyses

Mechanical and acoustical instrumental tests can help to predict and compare the sensory crispness of food products. This study proposed a method to correlate crispness sensory analyses to instrumental parameters using the standard products of the Spectrum Crispness Sensory Scale. An acoustic system was developed with a high-sampling rate for characterizing food crispness. Force-displacement and acoustic signals were measured during penetration and compression tests of the products in the Spectrum Scale. A band-pass filter suppressed the texture analyzer's engine and gearbox noise. High correlations were obtained between acoustical and sensory parameters in both tests; however, the penetration test better differentiated the products. The high-sampling rate acoustical measurement system was capable of discriminate crispy products, although the trained sensory panel was still more sensitive to small differences.

Influence of Potato Crisps Processing Parameters on Acrylamide Formation and Bioaccesibility

A fractional factorial design was used to evaluate the effects of temperature, frying time, blanching treatment and the thickness of potato slices on acrylamide content in crisps. The design was used on freshly harvested and four-month stored potatoes. The critical factors found were temperature and frying time, and the interaction between blanching treatment and slice thickness. Once frying conditions were selected, an acrylamide content of 725 and 1030 mg kg-1 was found for non-stored and 4-month stored tubers, with adequate textural parameters in both cases. The difference in concentration is related to storage conditions, which must be controlled in order to control acrylamide levels. Bioaccesibility studies demonstrated that acrylamide concentration remained at 70%, and reductions took place mainly at the intestinal phase, as a result of reaction with nucleophilic compounds.

Acoustic settings combination as a sensory crispness indicator of dry crispy food

Crispness is a critical attribute of quality for crispy products, which can be evaluated through both instrumental and sensory analyses. The aim of the study was to identify the best combination of settings of a device coupled to a texture analyzer for acoustic analysis in order to find strong correlations with the sensory texture. For that, nine commercial food products were submitted to force and acoustic (acoustic envelope detector) analyses, using two settings for acoustic data acquisition (gain 1 and gain 4), and two settings for acoustic data management (threshold 0.5 and 2.5). The products were also evaluated using texture descriptive sensory analysis. The gain changing from 1 to 4 (enhancing the test sensitivity) increased the number of acoustic peaks and reduced the sound pressure level. Changing the threshold from 0.5 to 2.5 (reducing the interference of background noise on the acquired data) reduced the number of acoustic peaks. The correlation between the instrumental and the sensory analysis showed gain 1 as the most adequate acoustic setting to obtain the acoustic parameters of products with different crispness intensities. Moreover, threshold 2.5 is the most appropriate for acoustic data collection. Therefore, sensory attributes and instrumental properties strong correlations indicate that texture analyzer in combination with the acoustic envelope detector is a good instrument to mimic human mastication and texture perception, through both force and sound stimuli. This study about dry crisp food may contribute to the literature and food industry, as well to future studies about wet crispy and crunchy foods.

Effect of liquid sourdough technology on the pre-biotic, texture, and sensory properties of a crispy flatbread

The present study compared liquid sourdough technology with baker's yeast leavening when applied to the production of a semolina-based crispy flatbread. Following in vitro starch digestion, the results revealed the sourdough leavened flatbread to contain a lower percentage of rapidly digestible starch (16%), higher amounts of slowly digestible starch (27%) and inaccessible digestible starch (4.1%) compared with the baker's yeast leavened flatbread (20, 20, and 2.4%, respectively), making the former nutritionally healthier. The sourdough leavened bread was crispier, stiffer and more solid, as shown by texture analyses, although Raman spectroscopy revealed no differences in the crystallinity status of starch. The descriptive analyses show that the use of sourdough enhances the positive sensory traits, as rated by the consumer panel scores (6.08 vs. 5.56). In summary, the results indicate that the implementation of sourdough technology in the production of flat crispy breads could confer economic advantages to this product.

Potential Impact of Oat Ingredient Type on Oral Fragmentation of Biscuits and Oro-Digestibility of Starch-An In Vitro Approach

The aim of the present study was to determine how variation in the biscuit matrix affects both the degree of in vitro fragmentation and the starch hydrolysis that occurs during the oral phase of digestion. Using three different oat ingredient types (oat flour, small flakes, and big flakes) and baking powder (or none), six biscuits with different matrices were obtained. The instrumental texture (force and sound measurements) of the biscuits was analyzed. The samples were then subjected to in vitro fragmentation. The particle size distribution and in vitro oral starch hydrolysis over time of the fragmented samples were evaluated. The results showed that the samples presented different fragmentation patterns, mainly depending on the oat ingredient type, which could be related to their differences in texture. The biscuits made with oat flour were harder, had a more compact matrix and showed more irregular fragmentation and a higher percentage area of small particles than those made with big oat flakes, which were more fragile and crumbly. The highest degree of starch hydrolysis corresponded to the biscuits made with flour. Conclusions: Differences in the mechanical properties of the biscuit matrix, in this case due to differences in the oat ingredient, play a role in the in vitro fragmentation pattern of biscuits and in the oral phase of starch hydrolysis.

Applications of Non-destructive Technologies for Agricultural and Food Products Quality Inspection

The quality and safety of food is an increasing concern for worldwide business. Non-destructive methods (NDM), as a means of assessment and instrumentation have created an esteemed value in sciences, especially in food industries. Currently, NDM are useful because they allow the simultaneous measurement of chemical and physical data from food without destruction of the substance. Additionally, NDM can obtain both quantitative and qualitative data at the same time without separate analyses. Recently, many studies on non-destructive detection measurements of agro-food products and final quality assessment of foods were reported. As a general statement, the future of using NDM for assessing the quality of food and agricultural products is bright; and it is possible to come up with interesting findings through development of more efficient and precise imaging systems like the machine vision technique. The present review aims to discuss the application of different non-destructive methods (NDM) for food quality and safety evaluation.

Gluten-Free Snacks Based on Brown Rice and Amaranth Flour with Incorporation of Cactus Pear Peel Powder: Physical, Nutritional, and Sensorial Properties

An agroindustrial by-product (cactus pear peel) and whole grains flour (brown rice and amaranth) were used to present a gluten-free snack proposal. The effect of 5% (F1), 7% (F2), and 10% (F3) substitution of brown-rice flour for yellow cactus pear peel powder (Opuntia ficus-indica) on the snack physical, sensorial, and nutritional properties was evaluated. In addition, 20% of amaranth flour (Amaranthus caudatus) was used for all formulations. As the percentage of substitution increased, the a⁎ value increased, while the L⁎ decreased. The control snacks presented higher hardness, while the snacks with 10% substitution presented a greater crispness. The sensorial properties (overall liking, colour, crispness, and oiliness) reported that the samples containing cactus pear peel powder were the most accepted. The fat content decreased as the substitution percentage increased. The F3 formulation presented the best physical and sensorial properties and when compared with other commercial snack brands, it presented low fat and an adequate protein and fibre content. Therefore, snacks based on brown rice, amaranth, and cactus pear by-product could be considered as a good option of gluten-free product, contributing to reducing the lack of gluten-free products on the markets.

Impact of pre-drying and frying time on physical properties and sensorial acceptability of fried potato chips

In this work the effects of pre-drying and frying time on colour, oil, texture and sensorial acceptability (overall liking) of potato chips were evaluated. Potato chips were pre-dried for 0, 10, 20 and 30 min at 60 °C and fried in soybean oil at 190 °C for 60, 70 and 80 s. The colour parameters (L*, a* and b*) increased or decreased depending on the pre-drying and frying time. Hardness increased as the pre-drying and frying time increased. On the other hand, the water initially removed by pre-drying decrease the gradient of mass transfer (water-oil). The oil content reduced to (about 21%) in pre-dried samples when compared to control sample. Finally, sensorial evaluation showed that samples without pre-drying and/or fried for very short or very long times had low acceptance levels. The pre-drying and frying times influenced the colour, texture, water and oil content, and resulted into fried potato chips with better acceptance scores.

A comparison of food crispness based on the cloud model

The cloud model is a typical model which transforms the qualitative concept into the quantitative description. The cloud model has been used less extensively in texture studies before. The purpose of this study was to apply the cloud model in food crispness comparison. The acoustic signals of carrots, white radishes, potatoes, Fuji apples, and crystal pears were recorded during compression. And three time-domain signal characteristics were extracted, including sound intensity, maximum short-time frame energy, and waveform index. The three signal characteristics and the cloud model were used to compare the crispness of the samples mentioned above. The crispness based on the Ex value of the cloud model, in a descending order, was carrot > potato > white radish > Fuji apple > crystal pear. To verify the results of the acoustic signals, mechanical measurement and sensory evaluation were conducted. The results of the two verification experiments confirmed the feasibility of the cloud model. The microstructures of the five samples were also analyzed. The microstructure parameters were negatively related with crispness (p < .01).

PRACTICAL APPLICATIONS

The cloud model method can be used for crispness comparison of different kinds of foods. The method is more accurate than the traditional methods such as mechanical measurement and sensory evaluation. The cloud model method can also be applied to other texture studies extensively.

Non-invasive sensing for food reassurance

The main food quality traits of interest using non-invasive sensing techniques are sensory characteristics, chemical composition, physicochemical properties, health-protecting properties, nutritional characteristics and safety. A wide range of non-invasive sensing techniques, from optical, acoustical, electrical, to nuclear magnetic, X-ray, biosensor, microwave and terahertz, are organized according to physical principle.