The Hydration of Grains: A Critical Review from Description of Phenomena to Process Improvements

Antinutritional factors and protein digestibility of broad bean flours hydrolysed during soaking using vacuum enzyme impregnation

The hydrolysis of legume proteins improves their nutritional and functional properties. Usually done by mixing flour with an enzyme solution, the process can be simplified using vacuum enzyme impregnation during soaking. This study used vacuum impregnation with papain or bromelain to obtain hydrolysed broad bean flours. It examined the impact of vacuum impregnation and enzyme incorporation on hydration kinetics and the impact of hydrolysis and dehulling on antinutritional factors and protein digestibility. Vacuum impregnation accelerated hydration and enzyme incorporation did not alter the hydration rate. Maximum hydrolysis degrees were 9.1 % with papain and 8.8 % with bromelain after 4 h of soaking. Hydrolysis increased phytic acid, total phenolics, and tannins content while decreasing trypsin inhibitors. Dehulling increased phytic acid and trypsin inhibitors, reduced tannins, and enhanced protein digestibility. Vacuum enzyme impregnation during soaking was effective for hydration and protein hydrolysis, modifying the nutritional properties of broad bean flours.

Cookability of 24 pea accessions-determining factors and potential predictors of cooking quality

BACKGROUND

Cooking time and cooking evenness are two critical quantities when determining the cooking quality (termed cookability) of pulses. Deciphering which factors contribute to pulse cookability is important for breeding new cultivars, and the identification of potential cookability predictors can facilitate breeding efforts. Seeds from 24 morphologically diverse pea accessions were tested to identify contributing factors and potential predictors of the observed cookability using a Mattson cooker. Size- and weight-based measures were recorded, and seed-coat hardness was obtained with a penetrometer. Content of protein, starch (amylose and amylopectin), and phytate was also determined.

RESULTS

Distinct differences were found between wrinkled and non-wrinkled seeds in terms of water-absorption capacity, seed-coat hardness, and plunger-perforation speed. Potential predictive indicators of cooking time and cooking evenness were seed-coat hardness (r = 0.49 and r = 0.38), relative area gained (r = -0.59 and r = -0.8), and percentage of swelled seeds after soaking (r = -0.49 and r = -0.58), but only for non-wrinkled seeds. Surprisingly, the coefficients of variation for the profile area of both dry and swelled seeds appeared to be potential cookability predictors of all pea types (correlation coefficients around r = 0.5 and supported by principal component analysis). However, no strong correlation was observed between cookability and protein, starch, or phytate levels.

CONCLUSION

Using three types of instruments together with chemical components enabled the identification of novel cookability predictors for both cooking time and cooking evenness in pea. This study unveils the diverse quantitative aspects influencing cookability in pea. Considering both cooking time and cooking evenness, as well as seed-coat hardness, underscores the multifaceted nature of pulse cookability and offers important insights for future breeding strategies to enhance pea cultivars. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Ultrasound-mediated hydration of finger millet: Effects on antinutrients, techno-functional and bioactive properties, with evaluation of ANN-PSO and RSM optimization methods

Finger millet, rich in nutrients, faces bioavailability limitations due to antinutrients like phytates and tannins that can be reduced by ultrasound mediated hydration (USH). Here, USH process of finger millet was optimized by varying ultrasound amplitude, water to grain ratio (W:G), treatment time, and frequency for reducing antinutrients and improving techno-functional attributes. USH resulted in a maximum reduction of 73% and 71% in phytates and tannins, respectively. The process was modeled using artificial neural network (ANN) and response surface methodology (RSM). ANN outperformed RSM in process prediction, and particle swarm optimization (ANN-PSO) suggested optimal conditions: 76% amplitude, W:G of 3.5:1, 17.5 min treatment time at 40 kHz. USH samples showed higher β-sheet, β-turn, and random coil proportions, with lower α-helix levels. Multivariate analysis also identified higher amplitude and frequency, with shorter treatment time as desirable USH conditions. USH could aid in enhancing commercial viability and nutritional quality of finger millet.

Effect of cooking on structural changes in the common black bean (Phaseolus vulgaris var. Jamapa)

The cooking process is fundamental for bean consumption and to increase the bioavailability of its nutritional components. The study aimed to determine the effect of cooking on bean seed coat through morphological analyses with different microscopy techniques and image analyses. The chemical composition and physical properties of raw black bean (RBB) and cooked black bean (CBB) seeds were determined. The surface and cross-sectional samples were studied by Optical microscopy (OM), environmental scanning electron microscopy (ESEM), atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). The composition of samples showed significant differences after the cooking process. OM images and gray level co-occurrence matrix algorithm (GLCM) analysis indicated that cuticle-deposited minerals significantly influence texture parameters. Seed coat surface ESEM images showed cluster cracking. Texture fractal dimension and lacunarity parameters were effective in quantitatively assessing cracks on CBB. AFM results showed arithmetic average roughness (Ra) (121.67 nm) and quadratic average roughness (Rq) (149.94 nm). The cross-sectional ESEM images showed a decrease in seed coat thickness. The CLSM results showed an increased availability of lipids along the different multilayer tissues in CBB. The results generated from this research work offer a valuable potential to carry out a strict control of bean seed cooking at industrial level, since the structural changes and biochemical components (cell wall, lipids and protein bodies) that occur in the different tissues of the seed are able to migrate from the inside to the outside through the cracks generated in the multilayer structure that are evidenced by the microscopic techniques used.

Seed germination and seedling development assisted by ultrasound: gaps and future research directions

Since the early 1930s, when the first corn hybrids were grown commercially, innovations in the agriculture industry have had an unprecedent impact worldwide, helping to meet the demands for food of an exponentially growing population. In particular, seed technology research has contributed substantially to the improvement of crop performance over the years. Ultrasonic treatment of seeds is a green technology that promises to have an impact on the food industry, enhancing germination and seedling development in different species through the stimulation of water and oxygen uptake and seed metabolism. The increase in starch degradation has been associated with the stimulation of the α-amylases of the endosperm, but relatively few reports focus on how ultrasound affects seed germination at the biochemical and molecular levels. For instance, the picture is still unclear regarding the impact of ultrasound on transcriptional reprogramming in seeds. The purpose of this review is to assess the literature on ultrasound seed treatment accurately and critically, ultimately aiming to encourage new scientific and technological breakthroughs with a real impact on worldwide agricultural production while promoting sustainable practices on biological systems. © 2023 Society of Chemical Industry.

Decoding the decisive role of seed moisture content in physical dormancy break: filling the missing links

Species producing seeds with a water-impermeable seed coat, i.e., physical dormancy (PY), dominate the dry tropical forests. Despite increasing interest and understanding of the germination ecology of a PY species, less is known about how PY break occurs, particularly what changes lead to the opening of the 'water gap'. Based on the moisture conent (MC) attained, two ranges of PY may exist: shallow PY, a state with higher MC and seeds could reverse to a permeable state when the relative humidity increases; and absolute PY, a completely dry state. Here, we demonstrate that this MC variation between seeds affects preconditioning and the 'water-gap' opening stages. A conceptual model developed shows a strong relationship between temperature and duration, with high temperature breaking PY in seconds, but seasonal temperature fluctuations and constant temperatures require a longer time. The duration required at any conditions to break PY is purported to depend on the hydrophobic bonds of the lipids, which are likely weakened during the preconditioning, and the amount of water influences hydrolysis, leading to the 'water-gap' opening. We argue that the moisture content of the seeds and its interaction with biochemical compounds are a possible explanation for why only a proportion of PY seeds become permeable to water each year. Nonetheless, empirical investigations must validate these notions.

Comparison of the pretreatment methods for enhancing hydration of water-soaked adzuki beans (Vigna angularis)

Five pretreatments methods, cold plasma, pressure drop, heating, and bath-type and probe-type sonications were compared to shorten the rehydration process of adzuki bean (Vigna angularis) soaked before the cooking in terms of the hydration and softening efficacies. Moisture content and water activity of the probe-type sonicated beans were most dramatically increased as 11-45% and 0.59-0.97 after soaking for only 2 h, respectively (non-treated: 11-12% and 0.59-0.66). Accordingly, the probe-type sonicated beans were most rapidly softened as 27-5 N in the 2 h-soaking and exhibited the lowest hardness after soaking/cooking as ~ 0.97 N (non-treated: 27-21 N and ~ 5.5 N, respectively). According to scanning electron micrographs, these results can be attributed to formation of prominent fissures or scars in the hilum of the probe-type sonicated beans. Consequently, this study will be provide valuable information for developing a rational process in food industry to shorten the rehydration of the adzuki beans.

Hard-to-cook phenomenon in common legumes: Chemistry, mechanisms and utilisation

Future dietary protein demand will focus more on plant-based sources than animal-based products. In this scenario, legumes and pulses (lentils, beans, chickpeas, etc.) can play a crucial role as they are one of the richest sources of plant proteins with many health benefits. However, legume consumption is undermined due to the hard-to-cook (HTC) phenomenon, which refers to legumes that have high resistance to softening during cooking. This review provides mechanistic insight into the development of the HTC phenomenon in legumes with a special focus on common beans and their nutrition, health benefits, and hydration behaviour. Furthermore, detailed elucidation of HTC mechanisms, mainly pectin-cation-phytate hypothesis and compositional changes of macronutrients like starch, protein, lipids and micronutrients like minerals, phytochemicals and cell wall polysaccharides during HTC development are critically reviewed based on the current research findings. Finally, strategies to improve the hydration and cooking quality of beans are proposed, and a perspective is provided.

Cold plasma as a pre-treatment for processing improvement in food: A review

Thermal processes can be very damaging to the nutritional and sensory quality of foods. Non-thermal technologies have been applied to reduce the impact of heat on food, reducing processing time and increasing its efficiency. Among many non-thermal technologies, cold plasma is an emerging technology with several potential applications in food processing. This technique can be used to preserve and sanitize food products, and act as a pre-treatment for drying, extraction, cooking, curing, and hydrogenation of foods. Furthermore, the reacting plasma species formed during the plasma application can change positively the sensory and nutritional aspects of foods. The aim of this review is to analyze the main findings on the application of cold plasma as a pre-treatment technology to improve food processing. In its current maturity stage, the cold plasma technology is suitable for reducing drying time, increasing extraction efficiency, as well as curing meats. This technology can convert unsaturated into saturated fats, without forming trans isomers, which can be an alternative to healthier foods. Although many advantages come from cold plasma applications, this technology still has several challenges, such as the scaling up, especially in increasing productivity and treating foods with large formats. Optimization and control of the effects of plasma on nutritional and sensory quality are still under investigation. Further improvement of the technology will come with a higher knowledge of the effects of plasma on the different chemical groups present in foods, and with the development of bigger or more powerful plasma systems.

Food processing to reduce antinutrients in plant-based foods

Antinutrients such as phytic acids, tannins, saponin, and enzyme inhibitors are phytochemicals that can decrease the bioavailability of micro- and macronutrients, thus causing them to be unavailable for absorptions in the digestive system. Antinutrients are a major concern especially in countries where plant-based commodities such as wheat, legumes, and cereals are staple foods, for the antinutrients can cause not only mineral deficiencies, but also lead to more serious health issues. Although various thermal and non-thermal processing methods such as cooking, boiling, and fermentation processes have been practiced to decrease the level of antinutrients, these processes may also undesirably influence the final products. More advanced practices, such as ozonation and cold plasma processing (CPP), have been applied to decrease the antinutrients without majorly affecting the physicochemical and nutritional aspects of the commodities post-processing. This review will cover the types of antinutrients that are commonly found in plants, and the available processing methods that can be used, either singly or in combination, to significantly decrease the antinutrients, thus rendering the foods safe for consumption.

Multivariate Analysis on the Properties of Intact Cereal Kernels and Their Association with Viscoelasticity at Different Moisture Contents

The viscoelastic properties of cereal kernels are strongly related to their quality, which can be applied to the development of a more selective and objective classification process. In this study, the association between the biophysical and viscoelastic properties of wheat, rye, and triticale kernels was investigated at different moisture contents (12% and 16%). A uniaxial compression test was performed under a small strain (5%), and the increase in viscoelasticity at 16% moisture content corresponded to proportional increases in biophysical properties such as the appearance and geometry. The biophysical and viscoelastic behaviors of triticale were between those of wheat and rye. A multivariate analysis showed that the appearance and geometric properties significantly influenced kernel features. The maximum force showed strong correlations with all viscoelastic properties, and it can be used to distinguish between cereal types and moisture contents. A principal component analysis was performed to discriminate the effect of the moisture content on different types of cereals and to evaluate the biophysical and viscoelastic properties. The uniaxial compression test under a small strain and the multivariate analysis can be considered a simple and non-destructive tool for assessing the quality of intact cereal kernels.

Improvement in nutritional quality of traditional unleavened flat bread using Quality Protein Maize

Maize grains are consumed majorly in the form of unleavened flat bread (chapatti) in the South East Asian region. The landraces are better accepted for their chapatti-making attributes such as grain color and good organoleptic properties. However, these cultivars are low in essential amino acids, particularly lysine and tryptophan content. Hence, an investigation was performed to identify maize genotypes with high nutritional value coupled with good chapatti-making qualities. Seven genotypes, comprising two Quality Protein Maize (QPM) hybrids, two normal maize hybrids, and three normal white maize landraces were assessed for their physical characteristics, proximate composition, and chapatti-making quality. Landrace 593 showed the highest protein and ash content. Flours obtained from different genotypes were significantly different (p ≤ 0.001) in terms of protein content, color value, textural, as well as mineral content. PMH 10 and IQMH 203 exhibited the highest and lowest hydration index, respectively. Two QPM hybrids showed significantly higher lysine and tryptophan content as compared to other genotypes. QPM hybrids were identified as the promising material with improved nutritional quality with respect to chapatti making. In combination with mustard greens, maize chapatti constitutes an important traditional delicacy in north India. The enhanced nutritional quality of QPM chapattis is an added advantage. We show the differentiation of chapattis made from QPM and normal maize using a rapid protocol developed previously. This is expected to enable the development and quality control of commercial enterprises based on high protein quality QPM.

A Preliminary Study on the Effect of the Instant Controlled Pressure Drop Technology (DIC) on Drying and Rehydration Kinetics of Maize Kernels (Zea mays L.)

Maize is one of the three worldwide cereal crops with the most outstanding production; however, its postharvest losses range from 2 to 40% due to inadequate harvesting, drying, and storage technologies. This study focuses on the Instant Controlled Pressure Drop technology (DIC) effect on maize kernels’ drying and rehydration kinetics. In total, 19 different DIC treatments were carried out on maize kernels (~25% d.b.). The DIC parameters studied were steam pressure (0.1 to 0.4 MPa) and treatment time (10 to 90 s). After DIC treatment, drying kinetics were carried out by Convective Air Drying (CAD) at 50 °C and 0.4 ms⁻¹ airflow. Rehydration kinetics and Water Holding Capacity (WHC) were evaluated at 20 °C. In comparison to CAD samples, DIC (0.4 MPa and 90 s) reduced the drying time from 180 min to ~108 min. Additionally, regarding the rehydration and WHC results, DIC achieved the same moisture content in only 3.5 min that controls achieved after 1 h of rehydration (0.40 g H₂O/g dry matter). Moreover, DIC (0.4 MPa and nine cycles of 10 s) increased the WHC 2.3 times compared to the control. In this way, DIC could be a postharvest technology to improve maize kernels’ drying operations and functional properties.

Impact of low-frequency ultrasound technology on physical, chemical and technological properties of cereals and pseudocereals

Cereals (CE) and pseudocereals (PSCE) play a pivotal role in nourishing the human population. Low-frequency ultrasound (LFUS) modifies the structure of CE and PSCE macromolecules such as starch and proteins, often improving their technological, functional and bioactive properties. Hence, it is employed for enhancing the traditional processes utilized for the preparation of CE- and PSCE-based foods as well as for the upcycling of their by-products. We report recent advances in LFUS treatments for hydration, germination, extraction of bioactive compounds from by-products, and fortification of CEs and PSCE, including kinetic modelling and underlying action mechanisms. Meta-analyses of LFUS influence on compounds extraction and starch gelatinization are also presented. LFUS enhances hydration rate and time lag phase of CE and PSCE, essential for germination, extraction, fermentation and cooking. The germination is improved by increasing hydration, releasing promoters and eliminating inhibitors. Furthermore, LFUS boosts the extraction of phenolic compounds, polysaccharides and other food components; modifies starch structure, affecting pasting properties; causes partial denaturation of proteins, improving their interfacial properties and their peptides availability. Overall, LFUS has an outstanding potential to improve transformation processes and functionalities of CE and PSCE.

Adzuki bean (Vigna angularis): Chemical compositions, physicochemical properties, health benefits, and food applications

Adzuki bean (Vigna angularis), also called red bean, is a legume of Fabaceae (Leguminosae) family. This crop is native to East Asia and is also commercially available in other parts of the world. It is becoming a research focus owing to its distinct nutritional properties (e.g., abundant in polyphenols). The diverse health benefits and multiple utilization of this pulse are associated with its unique composition. However, there is a paucity of reviews focusing on the nutritional properties and potent applications of adzuki beans. This review summarizes the chemical compositions, physicochemical properties, health benefits, processing, and applications of adzuki beans. Suggestions on how to better utilize the adzuki bean are also provided to facilitate its development as a functional grain. Adzuki bean and its components can be further developed into value-added and nutritionally enhanced products.

Enzyme and Antioxidant Activities of Malted Bambara Groundnut as Affected by Steeping and Sprouting Times

Bambara groundnut (BGN) is termed a complete food due to its nutritional composition and has been researched often for its nutritional constituents. Malting BGN seeds have shown improved nutritional and functional characteristics, which can be used to produce an amylase-rich product as a functional ingredient for food and beverage production in homes and industries. The aim of this study was to investigate the enzyme and antioxidant activities of malted BGN affected by steeping and sprouting times. BGN was malted by steeping in distilled water at 25-30 °C for 36 and 48 h and then sprouted for 144 h at 30 °C. Samples were drawn every 24 h for drying to study the effect of steeping and sprouting times on the moisture, sprout length, pH, colour, protein content, amylase, total polyphenols, and antioxidant activities of the BGN seeds. The steeping and sprouting times significantly affected the BGN malt colour quality and pH. The protein content of the malted BGN seeds was not significantly different based on steeping and sprouting times. Steeping and sprouting times significantly affected the α- and β-amylase activities of the BGN seeds. The activity of amylases for 36 and 48 h steeping times were 0.16 and 0.15 CU/g for α-amylase and were 0.22 and 0.23 BU/g for β-amylase, respectively. Amylase-rich BGN malt was produced by steeping for 36 h and sprouting for 96 h. Amylase-rich BGN malt can be useful as a functional food ingredient in food and beverage formulations.

Modelling multiphasic starch digestograms with multiterm exponential and non-exponential equations

The first-order kinetic and the Peleg models were respectively expanded to yield three-term exponential and non-exponential models for triphasic starch digestograms. Ten typical samples are presented, and the models suitably (r² > 0.95; p < 0.05) described their digestograms. Nonlinear regression constraints or conditions to ensure the stability, convergence, and practicability of the models are discussed. These were extended to existing two-term exponential models and an adapted two-term non-exponential model. The two-term models adequately (r² > 0.88; p < 0.05) described biphasic digestograms with practical digestion parameters, as exemplified by 10 presented digestograms. These multiterm models will add to models for describing multiphasic starch digestograms, ensuring such are properly modelled with objective predictability indices to assist researchers and for inter-laboratory comparisons. The integrals of the multiterm exponential and non-exponential models are presented to estimate or predict in vitro glycaemic indices.

Effect of high hydrostatic pressure on the edible quality, health and safety attributes of plant-based foods represented by cereals and legumes: a review

Consumers today are increasingly willing to reduce their meat consumption and adopt plant-based alternatives in their diet. As a main source of plant-based foods, cereals and legumes (CLs) together could make up for all the essential nutrients that humans consume daily. However, the consumption of CLs and their derivatives is facing many challenges, such as the poor palatability of coarse grains and vegetarian meat, the presence of anti-nutritional factors, and allergenic proteins in CLs, and the vulnerability of plant-based foods to microbial contamination. Recently, high hydrostatic pressure (HHP) technology has been used to tailor the techno-functionality of plant proteins and induce cold gelatinization of starch in CLs to improve the edible quality of plant-based products. The nutritional value (e.g., the bioavailability of vitamins and minerals, reduction of anti-nutritional factors of legume proteins) and bio-functional properties (e.g., production of bioactive peptides, increasing the content of γ-aminobutyric acid) of CLs were significantly improved as affected by HHP. Moreover, the food safety of plant-based products could be significantly improved as well. HHP lowered the risk of microbial contamination through the inactivation of numerous microorganisms, spores, and enzymes in CLs and alleviated the allergy symptoms from consumption of plant-based foods.

Nutritional Characteristics of Black Lentil from Soleto: A Single-Flower Vetch Landrace of Apulia Region (Southern Italy)

Archaeological remains and historical documents demonstrate that a single-flower vetch has been cultivated in Italy from the early stages of agriculture. Some Italian communities have perpetuated the custom to eat its seeds still to the present. This is the case of people living in some villages of the southern Apulia region. In consequence of the high resemblance of the single-flower vetch (Vicia articulata Hornem.) seeds with those of lentils, the Apulian landrace is locally named “lenticchia nera di Soleto” (black lentil from Soleto). The evaluation of seed nutritional traits of this landrace revealed good macronutrient contents (proteins and starch, 28.4 and 42.4 g/100 g respectively), low trypsin inhibitor levels (4.08 TIU/mg), short cooking times after soaking (24–25 min) and a lack of broken seeds at the end of cooking. The coat content of total phenolic compounds (TPC) of the Apulian black lentil was comparable with that of the lentil cv. Beluga (68.23 vs. 66.14 mg GAE/g, respectively).

Hybrid Treatment via MHz Acoustic Waves and Plasma to Enhance Seed Germination in Mung Bean

We investigate a hybrid treatment-consisting of an atmospheric pressure plasma pretreatment, followed by an MHz surface acoustic waves (SAWs) treatment with either de-ionized (DI) water or plasma activated water (PAW)-on mung beans to accelerate the germination process, as mung bean sprout is one of the important food staples. For the early growth rate (after 320 min), we observe that the hybrid treatment with PAW can lead to approximately 217% higher moisture content for the treated beans when compared with that without hybrid treatment. Additionally, the hybrid-treated beans germinate in around 120 min, while the untreated beans germinate only in around 420 min, that is, 3.5-fold faster for treated beans. This can be attributed to the dominant effect of SAW that accelerates stage 1 water absorption process and the effect of direct plasma and PAW that promote stage 2 metabolism process, leading to the enhancement in stage 3 germination process in early growth rate. For the post growth rate (after 24 h), we observe that the hybrid treatment with DI water can lead to an approximately 44.20% in higher moisture and 71.17% in radicle length when compared with untreated beans. Interestingly, the hybrid treatment with PAW, on the other hand, is observed to have an adverse effect on germination after 24 h, that is, approximately 14.51% lower in moisture content and 43.49% lower in radicle length for the hybrid-treated beans with PAW when compared with that with DI water.

Cold Atmospheric Pressure Plasma Treatment of Maize Grains-Induction of Growth, Enzyme Activities and Heat Shock Proteins

Zea mays L. is one of the most produced crops, and there are still parts of the world where maize is the basic staple food. To improve agriculture, mankind always looks for new, better methods of growing crops, especially in the current changing climatic conditions. Cold atmospheric pressure plasma (CAPP) has already showed its potential to enhance the culturing of crops, but it still needs more research for safe implementation into agriculture. In this work, it was shown that short CAPP treatment of maize grains had a positive effect on the vitality of grains and young seedlings, which may be connected to stimulation of antioxidant and lytic enzyme activities by short CAPP treatment. However, the prolonged treatment had a negative impact on the germination, growth, and production indexes. CAPP treatment caused the increased expression of genes for heat shock proteins HSP101 and HSP70 in the first two days after sowing. Using comet assay it was observed that shorter treatment times (30-120 s) did not cause DNA damage. Surface diagnostics of plasma-treated grains showed that plasma increases the hydrophilicity of the surface but does not damage the chemical bonds on the surface.

Mathematical Model for Describing Corn Grain Dehydration Kinetics after a Nixtamalization Process

In this research, the mathematical model associated with the hydrothermal dehydration process of Nixtamalized Corn Grains (NCG) with different Steeping Time (ST) values, allows the fitting of experimental data with initial moisture M0 and the equilibrium moisture ME as a function of Isothermal Dehydration Time (IDT). The moisture percentage for any time t and dehydration rate (isolines M(t) and isolines vI respectively) of the NCG is shown by means of matrix graphics as a simultaneous function of IDT and ST. The relationship between initial dehydration rate v0 and initial moisture M0 establishes as a function of ST. Also, the mathematical model associated with the solution of the second Fick's law allows calculating the diffusivity rate vk (H₂O molecules out of NCG) and verify that the rate of change in moisture and the dynamical proportionality constant k has a non-linear dependence on the IDT and that k is directly proportional to Deff. The k values strongly relate to ST and the calcium ions percentage into NCG according to solubility lime values into cooking water (or nejayote) as a function of decreasing temperature when ST increases.

Ultrasound-assisted hydration of finger millet (Eleusine Coracana) and its effects on starch isolates and antinutrients

Finger millet (Eleusine Coracana) is rich in nutrients and minerals. The iron and calcium contents are comparatively higher than other cereal crops. Finger millet also has some antinutrients such as tannins and phytates, that needs to be removed for maximum health benefits. Traditionally, these antinutrients are removed by the hydration process. The conventional hydration process is time cumbersome and often results in poor quality grains. Ultrasonication during hydration of finger millet could reduce the processing time and antinutrient content in finger millet. The ultrasound amplitude, treatment time, and grain to water ratio during hydration were optimized. An ultrasound amplitude of 66%, treatment time of 26 min, and a grain to water ratio of 1:3 resulted in best desirability parameters with a reduction in phytate and tannin contents of the finger millet by 66.98 and 62.83%, respectively. Ultrasonication during hydration increased the water binding capacity and solubility of the finger millet starch. XRD study of the starch isolates confirmed the increased crystallinity of the particles. FESEM of the starch isolates also confirmed that ultrasound-assisted hydration of finger millet resulted in the desired size reduction and homogeneous distribution of starch particles. The optimized ultrasound-assisted hydration could be adopted and scaled up for bulk processing of finger millets.

Modelling Volume Change and Deformation in Food Products/Processes: An Overview

Volume change and large deformation occur in different solid and semi-solid foods during processing, e.g., shrinkage of fruits and vegetables during drying and of meat during cooking, swelling of grains during hydration, and expansion of dough during baking and of snacks during extrusion and puffing. In addition, food is broken down during oral processing. Such phenomena are the result of complex and dynamic relationships between composition and structure of foods, and driving forces established by processes and operating conditions. In particular, water plays a key role as plasticizer, strongly influencing the state of amorphous materials via the glass transition and, thus, their mechanical properties. Therefore, it is important to improve the understanding about these complex phenomena and to develop useful prediction tools. For this aim, different modelling approaches have been applied in the food engineering field. The objective of this article is to provide a general (non-systematic) review of recent (2005-2021) and relevant works regarding the modelling and simulation of volume change and large deformation in various food products/processes. Empirical- and physics-based models are considered, as well as different driving forces for deformation, in order to identify common bottlenecks and challenges in food engineering applications.

Sono-hydro priming process (ultrasound modulated hydration): Modelling hydration kinetic during paddy germination

Application of ultrasound technology in modulating the hydration process during paddy germination was analyzed in this study. The effect of hydropriming (24 h) and sono-hydro priming (ultrasound priming, 12 h) on the hydration behaviour of paddies was determined at different temperatures (25-40 °C). Ultrasound pulse was applied for 10 min after every one hour for sono-hydro priming. Germination potential and microstructure analysis of treated paddies were also performed. Downward concave curve observed in hydration process of paddies indicates initial high-water absorptionthrough diffusion process. Sono-hydro priming process showed higher hydration rate compared to hydropriming. The changes in moisture content during hydration processes fitted to theoretical (Fick's model) and empirical model (Peleg model) exhibited high regression coefficient (R² > 0.95) indicating suitability for predicting hydration behaviour in both paddies for germination. The Peleg model adequately predicted saturation moisture content and sono-hydro priming efficiently increased the water absorption rate. Effective moisture diffusivity determined from Fick's diffusion model increased for sono-hydro priming. Activation energy estimated from effective moisture diffusivity required in sono-hydro priming (E_a = 20.32 and 19.19 KJ/mol respectively) for pigmented rice and non-pigmented rice was lower than hydropriming (E_a = 27.11 and 32.15 KJ/mol respectively). Both hydration processes were endothermic and non-spontaneous inferred from thermodynamic properties. Sono-hydro priming exhibited < 95% germination potential with shorter soaking time (12 h) owing to the high mass transfer rate. SEM micrograph revealed water absorption through various micro-cavities during sono-hydro priming. Thus, sono-hydro priming potentially reduced the soaking process (approximately 50%) with higher germination rate in paddies beneficial for commercial malting of grains.

High Temperature Rotational Rheology of the Seed Flour to Predict the Texture of Canned Red Kidney Beans (Phaseolus vulgaris)

The pasting profile of starchy tissues is conventionally measured by recording the apparent viscosity (η) in heating/cooling cycles. However, conventional rheometers show critical limitations when the starch is embedded in compact protein-rich cotyledon matrices, as occurs in pulses. In this work, the pasting profile of 13 red kidney beans (Phaseolus vulgaris) from the same cultivar but different growing locations was investigated using a heating/cooling cycle at higher temperature (130 °C) and pressurized conditions, using both water and brine as cooking solvents. It was hypothesized that the continuous measure of η at these conditions of flours from the dry seed would correlate with the texture, as determined by the mini-Kramer cell, of the beans after the entire process of soaking and canning. Furthermore, mechanistic answers were obtained by investigating their composition (starch, protein, and ash content) and physical properties (water holding capacity, seed ratio and weight). Interestingly, as opposed to the pasting profile at 95 °C, pasting indicators at 130 °C, including trough and final viscosity, strongly correlated with starch and protein content, seed coat ratio and, remarkably, with the firmness of the beans after canning when brine was incorporated. These results clearly show that small beans with a high protein content would bring about a more compact matrix that restricts starch from swelling and results in canned beans with a hard texture, which can be predicted by a lower pasting profile of the whole bean flour.

3D imaging of bean seeds: Correlations between hilum region structures and hydration kinetics

X-ray micro-CT imaging has been applied successfully in food science and seed research due to its capacity to provide very small details of seed traits that are very complex to score. The micropyle and the tissues of the hilum region of bean seeds are recognized as structures which play an important role in hydration process. This latter influences, in turn, not only germination but also the cooking and industrial processing. Nevertheless, the role of each structure of the bean seeds is yet to be fully understood. Moreover such traits are never been quantified by using 3D imaging approaches. In this work, seeds of four ancient Italian landraces of beans have been scanned by X-ray microCT with a twofold approach: bulk scans for whole seed imaging and single seed scans for internal traits measurements. Then water uptake tests have been performed. The different structures composing the hilum region of the beans have been imaged and characterized. The two-dimensional and the three-dimensional morphometric traits have been correlated with parameters of hydration models by Principal Component Analysis (PCA) and Pearson coefficients. Micropyle groove area was the trait most influencing the very initial hydration rates while the hilum groove area was the best correlated with the overall infiltration behavior. The internal free space was the trait best correlated with the moisture at equilibrium. Moreover, strophiole shape resulted the most suitable internal trait for univocal identification of the four landraces. Overall results give a contribution to the understanding of the role of hilum region structures in bean seeds hydration process and show novel morphological traits useful for identification of local bean landraces.