Acorn Flour Research Articles

Physicochemical, Functional, Antioxidant, Pasting and FT-IR Spectroscopic Properties of Fermented Acorns and Sorghum Using Traditional Algerian Processes

The fermentation of acorns and sorghum is an ancient practice among the inhabitants of northeastern Algeria. This study aimed to establish the traditional fermentation processes of acorns and sorghum through a regional survey conducted in Algeria. Additionally, it investigated the impact of fermentation on the physicochemical, functional, antioxidant, and pasting properties, as well as the FT-IR spectroscopic profiles of the flours derived from these fermented materials. Characteristics of fermented sorghum and acorn flours were compared with those of non-fermented flours. The study included a survey that was carried out in Algeria at the regional level to establish the traditional processes for fermented acorns and sorghum. The key findings reveal the existence of two production methods: the first, the oldest, involves fermentation in underground pits called Matmor, while the second, more recent, is conducted outside the Matmor. Most manufacturers employed the new process outside of the Matmor, usually in various sized and shaped containers to meet market demand. Acorns and sorghum flour, obtained by drying and grinding fermented acorns and fermented sorghum grains according to the process carried out outside the Matmor, are characterized by a unique biochemical, functional, and structural composition. Detailed analysis of the flours showed a significant decrease in their physicochemical properties after fermentation, with a simultaneous overall increase in antioxidant activity. Moreover, FT-IR spectroscopy suggests that fermentation differentially affects protein secondary structure and starch crystallinity.

In Vitro Digestion of Polyphenolic Compounds and the Antioxidant Activity of Acorn Flour and Pasta Enriched with Acorn Flour

Acorn flour is a rich source of nutrients and is beneficial to human health due to, among other things, its low glycemic index and polyphenol content. In order to obtain more accurate data on the levels and activities of the substances tested after ingestion and digestion, it may be beneficial to use a simulated in vitro digestion method. Therefore, the objective of the present study was to elucidate the content of polyphenols, individual phenolic acids, flavonoids and antiradical properties of acorn flour and pasta enriched with acorn flour before and after simulated in vitro gastrointestinal digestion. The results indicate that the total polyphenol content (TPC), flavonoid content and radical scavenging activity exhibited an increasing trend following the initial digestion stage and a decreasing trend following the second stage. Nevertheless, the levels of phenolic acids demonstrated an increase in both digestion phases. The digestion processes of polyphenols in acorn flour differ significantly from those in pasta. In the case of pasta, total polyphenols, phenolic acids and flavonoids, as well as free radical scavenging properties, demonstrated a decreasing trend following each digestion stage.

The Effects of Acorn Flour on Some Quality Characteristics of Chicken Patties

The study was carried out to develop chicken patties by incorporating acorn flour as a meat replacer at 3%, 6%, and 9% levels in the formulation. For this purpose, the chemical (moisture, protein, fat, ash), pH, thiobarbituric acid (TBA), and color analyses in the raw and cooked chicken patties were analyzed. In addition, the cooking properties (cooking yield, diameter reduction, thickness reduction), functional properties (moisture and fat retention) and sensory properties were examined on cooked chicken patties. There were significant changes in the chemical, cooking, functional, and color properties of chicken patties with acorn flour. The moisture and protein values decreased, in both raw and cooked samples incorporated with acorn flour but fat level increased only in raw acorn flour added samples. Lightness (L*) and redness (a*) values decreased significantly. The addition of acorn flour caused an increase in b* values of raw samples and a decrease in cooked samples. Acorn flour was not effective in preventing lipid oxidation. The addition of acorn flour contents in chicken patties improved functional and cooking properties, decreased cooking loss, and increased moisture and fat retention. The use of acorn flour improved the quality parameters of patties, but the addition of acorn flour resulted in a darker color in patties. The use of acorn flour in chicken meatballs did not negatively affect sensory properties except color. In conclusion, acorn flour can be used as a filler and binder in chicken patties.

Acorn (Quercus ithaburensis) Flour's effect on the physicochemical, textural, and sensory characteristics of raw and cooked beef meatballs

This research focused on examining the physicochemical properties, cooking attributes, textural qualities, and sensory analyses of meatballs containing varying percentages (control - 0%, 3%, 6%, and 9%) of acorn flour. The investigation encompassed both raw samples (on days 1, 3, 5, and 7) and cooked samples (on days 0, 4, 7, 10, and 14), all stored at a temperature of 4 ± 2 °C. Compared to the control group, the moisture, ash, and protein values of the cooked meatballs containing acorn flour decreased, while the fat values increased. However, there was no statistically significant difference between the moisture, ash, and protein values (P > 0.05). It was found that the pH levels of raw and cooked meatball groups decreased over the course of storage. L* values of meatballs were affected by adding acorn and darker-colored meatballs tended to have higher a* values. It was found that acorn flour was not effective in preventing lipid oxidation in raw and cooked meatballs during storage. It was found that the cooking efficiency, thickness increase, water holding capacity, and moisture retention values of the meatballs were improved when acorn flour was added (P < 0.05). Although the fat retention value of the meatball samples increased when the acorn flour level was increased from 3% to 9%, it was determined that there was no significant difference between the meatball groups (P > 0.05). Compared to the control group, the addition of acorn flour increased the hardness values and decreased the adhesiveness, cohesiveness, springiness, gumminess, and chewiness values. In general, as a result of the use of acorn flour in meatballs, sensory properties other than color were not adversely affected.

Blood-biochemical Indicators of White Texas, Pharaoh Quails During Temperature Stress

In the development of poultry farming in Azerbaijan, there are big changes in the microclimate indicators in the building due to the rise in temperature in the summer months. The variability in the microclimate, in turn, affects the productivity of the birds and the blood-biochemical indicators. The research work was carried out on White Texas, Pharaoh meat-oriented quails in laboratory no. 23 of the Anatomy, Pathoanatomy and Pathophysiology department of the Azerbaijan State Agrarian Univer­sity’s training and practice center for quail breeding. The experiment was carried out mainly in hot summer days depending on the air temperature, and during the experiment, the indicators formed in the homeostasis of the quails along with their productivity were clarified. In order to investigate the reasons preventing high yield from White Texas, Pharaoh quails during temperature stress, we aimed to study the factors affecting their homeostasis along with studying other factors. In the article, a change in the feed ration of quails was made in order to avoid the negative factors created in homeostasis caused by temperature stress which occurs frequently among quails in the summer months. It is better to keep full-grown quails in cages under the shed during the warm months. We reduced the amount of corn, wheat and barley used in the ration and replaced it with other non-traditional feeds determining the period in advance when temperature stress will increase. To prevent changes in homeostasis, acorn flour from non-traditional forages was used in the feed ration. This feed supplement-acorn flour was applied to each quail per a day in order to increase temperature tolerance during temperature stress.

The Quality Assessment of Starch Based Noodles Enriched with Acorn Flour, Cooking Characteristics, Physical, Chemical and Sensorial Properties

The Quality Assessment of Starch Based Noodles Enriched with Acorn Flour, Cooking Characteristics, Physical, Chemical and Sensorial Properties

Utilization of Oak (genus Quercus) tree parts in food industry: a review

Abstract Acorns, the fruit of the oak tree, as well as oak leaves have been for a long time an important source of food in various cultures throughout history. However, over the time they have disappeared from the diet and their usage in the food industry was minimal, especially due to the high tannin content and astringency. Despite that, several products have begun to appear on the market in the recent years such as an acorn flour or acorn coffee substitute and some studies were focused on the possibilities of using oak leaves extracts as a natural antioxidant against protein and lipid oxidation in the meat industry as well as for the beverage production.

Effect of oil extraction on physicochemical and structural properties of starch isolated from acorn (Quercus brantii).

Acorn (Quercus brantii) is a rich source of starch. Since the presence of lipids affects the physicochemical properties of starch and the extraction of nutritious acorn oil and its starch is economical, it's essential to study the acorn starch characteristics before and after oil extraction. Firstly, the best condition for reaching the maximum extraction yield of acorn starch (AS) was determined, and defatted acorn starch (DAS) was extracted in the same conditions. Then the physicochemical properties of both samples were compared. The structural properties were investigated by Scanning Electron Microscopy images. The maximum yield of AS was obtained in a 1:10 ratio (acorn flour: water) at 45 °C and 180 min. Results demonstrated significant differences between color parameters and fat content (0.65 ± 0.04 and 12 ± 0.02) of AS and DAS. Also, DAS had higher swelling power, solubility, and lower turbidity than AS. The X-ray diffraction pattern showed that AS was C-type with relative crystallinity of 27.77 %. Pasting, thermal, and textural properties reflected the higher viscosity, gelatinization, retrogradation, and hardness for DAS compared to AS. Consequently, all of these analyses exhibited structural changes in acorn starch by removing lipids from acorn flour and provided essential information for further applications of acorn starch in different industries.

Effect of inulin polymerization degree on nutritional and technological characteristics of gluten free bread

Introduction: Wheat bread is the staple food all over the world. Gluten sensitivity in some people has led to the development of gluten-free ones. Inulin is a soluble dietary fiber with beneficial nutritional effects is able to restore the function of gluten in gluten-free products by increasing water absorption and creating a structure. The function of gluten depends on its polymerization degree. This study is aimed to investigate the effect of inulin polymerization degree on the technological and nutritional characteristics of rice-acorn flour based gluten-free bread.&#x0D; Methods: This study is an experimental type. To investigate the effect of the inulin polymerization degree on technological and nutritional characteristics of rice:acorn flour based gluten-free bread, the textural, physicochemical, sensory characteristics and inulin stability of samples enriched inulin with different polymerization degree were assessed. All tests were done in triplicate. Data analysis was done with SPSS 25 software&#x0D; Results: Results indicated that the optimized technological characteristics and lowest inulin loss ratio (31% w/w-1) is found at gluten-free bread samples containing 30% w/w-1 of acorn flour and long-chain inulin fermented by MF-SD (A30R70SL). Long-chain inulin is found to be able to restore gases produced during the fermentation and expanded through cooking process, which seems to be induced by its potential ability to form a gel.&#x0D; Conclusion: Using long-chain inulin is recommended to achieve desirable technological characteristics and high nutritional value in the formulation of gluten-free bread.

Effects of Feeding Oak Acorn Flour on Hematology and Serum Biochemical Profile, and Carcass Characteristics of Japanese Quail

Effects of Feeding Oak Acorn Flour on Hematology and Serum Biochemical Profile, and Carcass Characteristics of Japanese Quail

In vitro and in vivo glycemic responses and antioxidant potency of acorn and chickpea fortified gluten-free breads

Gluten-free (GF) breads, based on rice flour and corn starch (50:50), were fortified with a mixture of acorn flour (ACF) - chickpea flour (CPF) at 30% substitution level of corn starch (i.e., rice flour:corn starch:ACF-CPF 50:20:30) using different flour blends of ACF:CPF at weight ratios of 5:25, 7.5:22.5, 12.5:17.5, and 20:10 in order to improve the nutritional quality and antioxidant potential as well as the glycemic responses of the GF breads; a control GF bread with rice flour:corn starch 50:50 ratio was also prepared. ACF was richer in total phenolic content than CPF, whereas CPF was characterized by higher amounts of total tocopherols and lutein compared to ACF. For both ACF and CPF as well as the fortified breads, the most abundant phenolic compounds were gallic (GA) and ellagic (ELLA) acids as found by HPLC-DAD analysis, while a hydrolysable tannin, valoneic acid dilactone, was also identified and quantified by HPLC-DAD-ESI-MS in high amount in the ACF-GF bread having the highest level of ACF (ACF:CPF 20:10), even though it seemed to decompose during breadmaking, possibly into GA and ELLA. Therefore, the inclusion of these two raw materials as ingredients in GF bread formulations resulted in baked products with enhanced concentrations of such bioactive compounds and higher antioxidant activities, as indicated by three different assays (DPPH, ABTS and FRAP). The extent of glucose release, as evaluated by an in vitro enzymic assay, was negatively correlated (r = −0.96; p = 0.005) with the level of added ACF, and was significantly reduced for all ACF-CPF fortified products when compared with their non-fortified GF counterpart. Furthermore, the GF bread containing a flour mixture of ACP:CPF at a weight ratio of 7.5:22.5, was subjected to an in vivo intervention protocol to assess the glycemic response when consumed by 12 healthy volunteers; in this case, white wheat bread was used as reference food. The glycemic index (GI) of the fortified bread was significantly lower compared to the control GF bread (97.4 versus 159.2, respectively), which along with its lower amount of available carbohydrates and the higher level of dietary fibers, resulted in a significantly reduced glycemic load (7.8 versus 18.8 g per serving of 30 g). The present findings underlined the effectiveness of acorn and chickpea flours in improving the nutritional quality and glycemic responses of fortified GF breads with these flours.

The effect of acorn muffin consumption on glycemic indices and lipid profile in type 2 diabetic patients: A randomized double-blind placebo-controlled clinical trial.

Acorn is a nutritious fruit with the reported potential of ameliorating diseases, including diabetes. This research aimed to assess the effects of acorn muffin consumption on glycemic, lipid indices, and appetite in patients with type 2 diabetes. Sixty-six subjects were dichotomized to receive either one muffin containing 10grams of acorn flour or a placebo muffin containing white wheat flour (no bran), per day, for 8 weeks. Acorn muffin consumption improved glycated hemoglobin (p= .06, mean difference [MD]=-0.65), triglyceride (p= .06, MD=-36.38), and high-density lipoprotein (p= .05, MD=1.30), albeit only marginally significantly. Among appetite parameters, hunger, desire to eat, and prospective to eat were significantly lower, and satiety and fullness were significantly higher, in the acorn muffin group. In conclusion, acorn muffins could be utilized as an adjuvant therapy to control appetite and ameliorate glycated hemoglobin in patients with type 2 diabetes. However, further investigations are required for a more comprehensive conclusion.

Acorn flour and sourdough: an innovative combination to improve gluten free bread characteristics

Nowadays, challenges in gluten free breads (GFB) are focused on improving the nutritional and health benefits. Acorn flour is an underexploited sustainable ingredient, naturally gluten free, with many nutritional and technological advantages. The aim of this study was to explore the interaction of acorn flour supplementation (up to 35%) to rice flour and sourdough process to obtain rice based GFB. Different levels of rice flour replacement with acorn flour (0%, 23% and 35%), and sourdough (20%) were tested in a basic GFB recipe, and technological, nutritional, and functional GFB characteristics evaluated. The combination of acorn flour and sourdough was responsible for acidifying dough and bread. Breads containing 35:65 acorn flour: rice flour led to harder breads with lower crumb luminosity and with reddish and brownish tones, besides improved structural features when adding sourdough. That combination of sourdough and acorn flour reduced the rate and the extent of starch hydrolysis, as well as increase the minerals content, total phenolic compounds and antioxidant activity. Therefore, the combination of acorn flour and sourdough process allows obtaining rice based GFB with better nutritional pattern.

Effects of Endogenous Non-Starch Nutrients in Acorn (Quercus wutaishanica Blume) Kernels on the Physicochemical Properties and In Vitro Digestibility of Starch.

The present study investigated the multi-scale structure of starch derived from acorn kernels and the effects of the non-starch nutrients on the physicochemical properties and in vitro digestibility of starch. The average polymerization degree of acorn starch was 27.3, and the apparent amylose content was 31.4%. The crystal structure remained as C-type but the relative crystallinity of acorn flour decreased from 26.55% to 25.13%, 25.86% and 26.29% after the treatments of degreasing, deproteinization, and the removal of β-glucan, respectively. After the above treatments, the conclusion temperature of acorn flour decreased and had a significant positive correlation with the decrease in the crystallinity. The aggregation between starch granules, and the interactions between starch granules and both proteins and lipids, reduced significantly after degreasing and deproteinization treatments. The endogenous protein, fat, and β-glucan played key roles in reducing the digestibility of acorn starch relative to other compounds, which was dictated by the ability for these compounds to form complexes with starch and inhibit hydrolysis.

Effects of Endogenous Polyphenols in Acorn (Quercus wutaishanica Blume) Kernels on the Physicochemical Properties of Starch

AbstractThe effects of endogenous polyphenols in acorn kernels on granule morphology, crystal properties, and in vitro digestibility of starch are investigated. The granule surface smoothness, relative crystallinity, short‐range molecular order, and starch hydrolysis rate increase after the removal of polyphenols from acorn flour. With the addition of polyphenol extracts, the hydrolysis rates of acorn, corn, potato, and chestnut starches are all reduced, and the free‐polyphenol extract shows higher inhibitory activity than the bound‐polyphenol extract. These results are expected to be helpful for understanding the low digestibility of starch in acorn kernels, which is attributed to the inhibitory effects of polyphenols on the activities of α‐amylase and α‐glucosidase, but not the increase of long and short‐range molecular orders of starch.

Acorn flour from holm oak (Quercus rotundifolia): Assessment of nutritional, phenolic, and technological profile

Acorn is the fruit of holm oak (Quercus rotundifolia), being mainly used nowadays to feed animals, however a substantial part remains in the fields without any valorization. Underexploited crops are gaining new interest, driven by food security concerns and health benefits potential as well. In the present work, it was studied the physicochemical characteristics and functional perspective of acorn flour, as an ingredient for human diet. The study included nutritional composition analysis, phenolic compounds profile through HPLC, starch content and its microstructure, fibre, and pasting properties assessment. Acorn flour presented a high content in fat, particularly monounsaturated and polyunsaturated (oleic and linoleic acids), and high minerals content in particular K. Concerning phenolic profile, rutin, catechin, ellagic acid, gallic acid, and syringic acid were identified. In regards to technological profile, fibre was mainly insoluble, with around 11%, and starch content was 50%. Its pasting behaviour revealed a high gelatinization temperature (85 °C), with low breakdown, and higher retrogradation consistency. These results show acorn flour potential as a valuable and sustainable multipurpose food ingredient.

The Rheological Performance and Structure of Wheat/Acorn Composite Dough and the Quality and In Vitro Digestibility of Its Noodles.

Wheat flour was partially replaced by debittered acorn flour (DAF) with 0%, 10%, 15%, 20% as well as 25%. Rheological properties of wheat/acorn dough and quality and in vitro digestibility of its noodles were determined. Results showed that DAF addition significantly improved pasting viscosity and dough stability time while excessive addition weakened the protein network and decreased maximum fermentation height. Furthermore, noodles with substitutions exhibited promising technological properties as a food ingredient for noodle making (higher hardness, chewiness, gumminess, firmness, and less cooking time) but poor extensibility, smaller lightness values, and a slight deterioration in cooking quality. Furthermore, PCA and correlation analysis demonstrated a significant relationship between textural and cooking properties and pasting and mixing parameters. Moreover, SEM images of acorn noodles presented coarser surfaces but a tighter cross-section structure. Finally, in vitro digestibility results indicated that DAF addition significantly reduced the susceptibility of the starches to enzyme hydrolysis, while the addition of acorn flour slightly decreased the overall acceptability. Thus, the partial substitution of wheat flour with acorn flour can favorably be used in noodles formulation.

Effect of varying levels of acorn flour on antioxidant, staling and sensory properties of Iranian toast

Due to the high level of antioxidant activity of acorn fruits, they can be used as an ingredient the production of functional foods. The goal of the this research was to partially substitute wheat flour with varying levels (10% - 50% w/w) of debittered acorn flour and to investigate its effects on the rheological characteristics of the dough, total phenolic content (TPC), staling, colour indices and sensory properties of toast bread. The farinograph degree of softening and water absorption of the dough decreased with increasing the acorn flour content, while the stability and time of development of the dough increased. Resistance and extensibility to deformation of the samples respectively increased and decreased compared to those of the control. Toast bread with 30% acorn flour replacement was observed to have lower staling than the control. The highest TPC (9.44 mg GAE/g) and the lowest peroxide value (0.36 m eq O2/kg) were obtained for the bread having 30% acorn flour substitution. Moreover, the breads showed darker crumbs with significantly lower specific loaf volumes. Overall, the bread with 30% of acorn flour substitution showed good rheological, staling properties and reasonable anti-oxidant content compared to the control bread as well as the highest sensorial acceptability.

Effect of varying levels of acorn flour on antioxidant, staling and sensory properties of Iranian toast

Due to the high level of antioxidant activity of acorn fruits, they can be used as an ingredient the production of functional foods. The goal of the this research was to partially substitute wheat flour with varying levels (10% - 50% w/w) of debittered acorn flour and to investigate its effects on the rheological characteristics of the dough, total phenolic content (TPC), staling, colour indices and sensory properties of toast bread. The farinograph degree of softening and water absorption of the dough decreased with increasing the acorn flour content, while the stability and time of development of the dough increased. Resistance and extensibility to deformation of the samples respectively increased and decreased compared to those of the control. Toast bread with 30% acorn flour replacement was observed to have lower staling than the control. The highest TPC (9.44 mg GAE/g) and the lowest peroxide value (0.36 m eq O2/kg) were obtained for the bread having 30% acorn flour substitution. Moreover, the breads showed darker crumbs with significantly lower specific loaf volumes. Overall, the bread with 30% of acorn flour substitution showed good rheological, staling properties and reasonable anti-oxidant content compared to the control bread as well as the highest sensorial acceptability.

Technological characteristics of inulin enriched gluten-free bread: Effect of acorn flour replacement and fermentation type.

Textural, physicochemical, and sensory characteristics of rice‐based gluten‐free bread in the presence of acorn flour; inulin and different fermentation type (yeast starter fermentation [Y] or mixed fermentation based on sourdough [MF‐SD]) were investigated. Acorn flour was added to replace rice flour at a proportion of 10, 30, and 50% W/W. Furthermore, the mixture flour was replaced by inulin as a functional prebiotic ingredient at 10% W/W. Considering results obtained at this study, using mixed fermentation based on sourdough and inulin at 10% W/W provide the structure able to restore gases through baking process at formulations containing acorn flour at 30% W/W (A30R70SL). The highest specific volume (1.47 ± 0.04 cm3 g−1) and the lowest hardness (40.97 ± 0.87 N) are observed in A30R70SL which seems to be induced by its potential to form gel. Acorn flour substitution level at 50% W/W adversely influenced the technological characteristics of final product and its perception by the consumer. Acorn flour substitution up to 30% W/W is preferred by the consumer which is attributed to its potential role to improve the unpleasant pale color of rice‐based gluten‐free products. A negatively significant correlation has been observed between the color perception by the consumer and crumb lightness (r = −.493, p ≤ .05).