Effect of cooking pressure on phenolic compounds, gamma-aminobutyric acid, antioxidant activity and volatile compounds of brown rice

An insight into the full aspects of bound polyphenols in dietary fiber: Interaction, composition, function and foundation as well as alteration in food processing

Dietary fiber (DF) and polyphenols are both bioactive compounds with various health-promoting effects while close relationship between them aroused wide concern in recent years. Abundant polyphenols combine with DF and contribute greatly to its beneficial effects. Although efforts made to uncover such bound polyphenols (BPs) from different angles before, systematic overview of full aspects is deficient. Here, more details about polyphenols conjugated in DF reported recently were summarized systematically. Meanwhile, the disposition of BPs in gastrointestinal tract and their interaction with microbiome were introduced to clarify the foundation of their functions. Moreover, considering the great impacts of food processing on polyphenols, different technics used in food handling were introduced with their effects on BPs emphatically discussed to provide guideline for reasonable application of specific technics for given materials. Our work is supposed to promote the understanding of BPs in DF and facilitate their future exploitation and application as a whole.

Effect of storage temperature on the quality of brown rice revealed by integrated GC-MS and lipidomics analysis

Brown rice is highly nutritious but more susceptible to deterioration without the rice husk's protection. In this study, the mechanism of storage temperature on brown rice quality was investigated based on GC-MS and lipidomics. The results showed that both 15 °C and 20 °C storage retarded the lipids oxidation of brown rice and maintained its texture properties. Moreover, 1-octanol, 1-octen-3-ol, octanal, fitone, 2, 3-dihydrobenzofuran, dodecane, and tridecane were key biomarkers in cooked brown rice flavor. Furthermore, significant correlations between lipid oxidation, texture, and flavor biomarkers were revealed. Notably, the quality of brown rice stored at 15 °C (Fatty acid value = 23.0 mg/100 g) was superior to that at 20 °C (Fatty acid value = 24.3 mg/100 g) due to more effective retardation of glycerophospholipid, glycerolipid, and phospholipid metabolism. This work provided a better understanding of temperature-controlled storage of brown rice and give recommendation for potential commercial applications.

Ferulic Acid—A Brief Review of Its Extraction, Bioavailability and Biological Activity

Ferulic acid is a widespread phenolic compound that occurs in seeds and leaves, both in its free form and conjugated to polysaccharides, carbohydrates, glycoproteins and lignins in the plant cell walls. It exhibits various biological activities, like antioxidant, anticarcinogenic, anti-inflammatory, hepatoprotective, antimicrobial, and antiviral activity, and it modulates enzyme activity. Given these wide potential health benefits, ferulic acid has attracted considerable research interest and may be considered a biomolecule with strong prospects as a functional food ingredient. Great attempts have been made to enhance its extraction process and recovery from natural matrices and agro-industrial wastes for its various applications relating to human health and nutrition. This review presents the recently available information on the extraction methods for quantifying ferulic acid in different samples, along with its bioavailability and stability in processing foods and biological activities.

Effect of cooking methods on volatile compounds and texture properties in maize porridge

To investigate the optimal processing of maize porridge, the volatile compounds and texture under different cooking methods and time have been studied. A total of 51 volatile compounds were identified in maize porridge. Notably, the major volatiles, aldehydes and esters exhibited a relatively high content in electric pressure cooker (EPC), and esters tend to significantly increase after cooking. Among aldehydes, nonanal and hexanal played a great role in flavor due to their relatively high content. Volatile compounds of maize porridge in different cooking methods could be clearly distinguished by multiple chemometrics. Furthermore, texture analysis revealed that almost all the indicators in the EPC can reach the lowest value at 60 min. To summarize, different cooking methods had a more significant influence on the volatile compounds and texture compared to time. This study helps to improve the sensory attributes of maize porridge, and thus contributes to healthier and more sustainable production.

Oxidative Stability and Pasting Properties of High-Moisture Japonica Brown Rice following Different Storage Temperatures and Its Cooked Brown Rice Flavor

The study proposed to investigate the impacts of storage temperatures (15, 20, 25 °C) on the oxidative stability (peroxide value, carbonyl value, malondialdehyde content) and sensory attributes (pasting properties, cooked brown rice flavor) of high-moisture japonica brown rice. According to the findings, the peroxide value, the carbonyl value, and the malondialdehyde content of high-moisture japonica brown rice stored at a temperature of 15 °C exhibited consistently low levels, and the pasting properties were favorable. In addition, 22 out of 51 flavor volatiles were screened as key differential volatile flavor compounds in cooked brown rice via a combination of ANOVA and orthogonal projections to latent structures-discriminant analysis (OPLS-DA). Among them, 3-heptylacrolein had an aroma of fat and mushroom, and its contents were higher at 15 °C and 20 °C. These findings could serve as a valuable reference for storing high-moisture japonica brown rice under low temperature conditions as well as for investigating the flavor characteristics of cooked brown rice derived from this variety.

Gamma-aminobutyric acid (GABA): a comprehensive review of dietary sources, enrichment technologies, processing effects, health benefits, and its applications

Gamma-aminobutyric acid (GABA) is a naturally occurring potential bioactive compound present in plants, microorganisms, animals, and humans. Especially, as a main inhibitory neurotransmitter in the central nervous system, GABA possesses a broad spectrum of promising bioactivities. Thus, functional foods enriched with GABA have been widely sought after by consumers. However, the GABA levels in natural foods are usually low, which cannot meet people's demand for health effects. With the increasing public awareness on the food securities and naturally occurring processes, using enrichment technologies to elevate the GABA contents in foods instead of exogenous addition can enhance the acceptability of health-conscious consumers. Herein, this review provides a comprehensive insight on the dietary sources, enrichment technologies, processing effects of GABA, and its applications in food industry. Furthermore, the various health benefits of GABA-enriched foods, mainly including neuroprotection, anti-insomnia, anti-depression, anti-hypertensive, anti-diabetes, and anti-inflammatory are also summarized. The main challenges for future research on GABA are related to exploring high GABA producing strains, enhancing the stability of GABA during storage, and developing emerging enrichment technologies without affecting food quality and other active ingredients. A better understanding of GABA may introduce new windows for its application in developing functional foods.

Dynamic Changes in Volatiles, Soluble Sugars, and Fatty Acids in Glutinous Rice during Cooking

Cooking is an important process before rice is consumed and constitutes the key process for rice flavor formation. In this paper, dynamic changes in aroma- and sweetness-related compounds were tracked during the entire cooking process (including washing with water, presoaking, and hydrothermal cooking). The volatiles, fatty acids, and soluble sugars in raw rice, washed rice, presoaked rice, and cooked rice were compared. After being washed with water, the total volatiles decreased while aldehydes and unsaturated fatty acids increased. Meanwhile, oligosaccharides decreased and monosaccharides increased. The changes in fatty acids and soluble sugars caused by the presoaking process were similar to those in the water-washing process. However, different changes were observed for volatiles, especially aldehydes and ketone. After hydrothermal cooking, furans, aldehydes, alcohols, and esters increased while hydrocarbons and aromatics decreased. Moreover, all fatty acids increased; among these, oleic acids and linoleic acid increased most. Unlike with washing and presoaking, all soluble sugars except fructose increased after hydrothermal cooking. Principal component analysis showed that cooked rice possessed a volatile profile that was quite different from that of uncooked rice, while washed rice and presoaked rice possessed similar volatile profiles. These results indicated that hydrothermal cooking is the pivotal process for rice flavor formation.

Effects of Soaking on the Volatile Compounds, Textural Property, Phytochemical Contents, and Antioxidant Capacity of Brown Rice

Brown rice is a staple whole grain worldwide. Hence, the effects of cooking on the nutritional properties of brown rice are important considerations in the field of public health. Soaking is a key stage during rice cooking; however, different rice cookers use different soaking conditions and the effects of this on the physiochemical properties and nutritional composition of cooked brown rice remain unknown. In this study, the setting of varied soaking conditions was realized by a power-adjustable rice cooker, and the effects of soaking temperature (40, 50, 60 and 70 °C) and time (30 and 60 min) on cooked brown rice were thoroughly analyzed. Textural results revealed that cooked brown rice was softer and stickier after soaking. Grain hardness decreased by increasing the soaking temperature and time. Furthermore, stickiness after soaking for 60 min was higher than that after 30 min, and this decreased with the soaking temperature. There was no significant unpleasant flavor after soaking, and the volatile compound profile between soaked and unsoaked brown rice was similar. Neither soaking temperature nor time had any significant effect on the phytochemical contents (phenolic compounds, α-tocopherol and γ-oryzanol) or antioxidant capacity of cooked brown rice, whereas γ-aminobutyric acid content was effectively preserved within a certain soaking temperature range. Textural properties can be effectively controlled by soaking temperature and time, and nutritional properties remain stable when soaking at 40-70 °C for 30-60 min.

Volatile Organic Compounds, Evaluation Methods and Processing Properties for Cooked Rice Flavor

Rice (Oryza sativa L.), as the main refined grain in China, has attracted much attention in terms of quality. Rice is usually consumed after cooking, and it is a commonly staple food. Nowdays, people's requirements for cooked rice focus more on the taste characteristics and quality. Furthermore, aroma is one of the primary sensory reference points, which is the most intuitive way for people to judge cooked rice. By integrating and analyzing the researches of cooked rice aroma identification in recent five years, this paper expounds the extraction and identification methods (sensory evaluation method, GC-MS, SPME, MOS sensors, electronic nose, etc.) of the flavor substances in cooked rice, as the processing methods and properties of cooked rice, and the volatile organic compounds of cooked rice under different conditions are summarized as well.

Effect of heat-moisture treated brown rice crackers on postprandial flow-mediated dilation in adults with mild endothelial dysfunction

Background

Endothelial dysfunction is an early pathophysiological feature and independent predictor of a poor prognosis in most forms of cardiovascular disease. We evaluated the effect of brown rice crackers (BR-C) on endothelial function.

Methods

Effect of heat-moisture treated (HMT) -BR-C on postprandial flow-mediated dilation (FMD) in adults with mild endothelial dysfunction was compared with that of BR-C and white rice crackers (WR-C) in 12 adults with mild endothelial dysfunction (less than 7.0% of FMD) by a randomized, single-blind, three-treatment three-period crossover trial (UMIN 000034898). Since we considered that the FMD increase was associated with the treatment of HMT-BR-C, we examined the effect of three possible factors: postprandial glucose levels, polyphenol content, and polyphenol release from the food matrix.

Results

Mean pre-intake baseline FMD values of HMT-BR-C, BR-C, and WR-C were 4.9%, 5.1%, and 4.9%, respectively, and those values 1 h post-intake were 6.3%, 5.1%, and 4.8%, respectively. There was no difference in intergroup comparisons of FMD using Dunnett's multiple comparison test. There was a significant increase in FMD only in HMT-BR-C in intragroup comparisons (P = 0.042 by paired-t test). In comparison with BR-C, no significant difference was noted in the postprandial glucose level nor in the content of total polyphenols and ferulic acid derivatives in HMT-BR-C. However, the 70% ethanol extracted from HMT-BR-C contained a significantly larger amount of free and bound ferulic acids than from BR-C.

Conclusion

HMT-BR-C intake increased the postprandial FMD response.