Microstructure and digestibility of potato strips produced by conventional frying and air-frying: An in vitro study

Formation of pores and bubbles and their impacts on the quality attributes of processed foods: A review

Pores and bubbles significantly influence the physical attributes (like texture, density, and structural integrity), organoleptic properties, and shelf life of processed foods. Hence, the quality of foods and their acceptance by the consumers could be influenced by the properties and prevalence of pores and bubbles within the food structure. Considering the importance of pores, this review aimed to comprehensively discuss the factors and mechanisms involved in the generation of pores and bubbles during the processing of different food products. Moreover, the characteristics and effects of pores on the properties of chocolates, cheeses, cereal-based foods (like cake, puffed grains, and pasta), dried, and fried products were discussed. The impacts of bubbles on the quality of foam-based products, foam creamers, and beverages were also explored. This review concludes that intrinsic factors (like food compositions, initial moisture content, and porosity) and extrinsic factors (like applied technologies, processing, and storage conditions) affect various properties of the pores and bubbles including their number, size, orientation, and distribution. These factors collectively shape the overall structure and quality of processed food products such as density, texture (hardness, cohesiveness, chewiness), and water holding capacity. The desirability or undesirability of pores and their characteristics depends on the type of products; hence, some practical hints were provided to mitigate their adverse effects or to enhance their formation in foods. For example, pores could increase the nutrient digestion and reduce the shelf life of the products by enhancing the risk of fat oxidation and microbial growth. In conclusion, this study provides a valuable resource for food scientists and industry professionals by discussing the effects of pores on food preservation, heat, and mass transfer (including oxygen, moisture, flavors, and nutrients). Understanding the dynamic changes in porosity during processing will be effective in customization of final product quality with desired attributes, ensuring tailored outcomes for specific applications.

Sodium alginate edible coating to reduce oil absorption of French fries with maintaining overall acceptability: Based on a water replacement mechanism

The effect of sodium alginate (SA) coating on the oil content and quality of fries was evaluated, and the inhibitory mechanism of SA on oil absorption was analyzed based on the water replacement theory. Compared to uncoated samples, the penetrated surface oil (PSO), structure oil (STO), and total oil (TO) contents, a*, and b* of coated fries decreased, whereas moisture content, L* and hardness increased with no significant difference revealed by sensory evaluation of all samples. The water contact angle of the films correlated negatively with the water content and hardness of the fries. In contrast, it correlated positively with PSO, STO, and TO contents. The TO content of fries with 1 % SA film which had a compact microstructure, was the lowest, reduced by 52.5 % compared to the control sample. SA coating reduces the pores and roughness on the fries' surface, which inhibits the oil from penetrating into the samples. SA coating decreased the T₂₁, T₂₂, and pores of the starch, and increased the P_2b, P₂₁, relative crystallinity, and ΔH significantly (P < 0.05). Therefore, SA coating inhibits the oil absorption in fries by reducing water evaporation which is attributed to the increase in double helices and crystallinity of starch.

The study of the nutritional and biological value of functional semi-finished fish products "fish balls"

In the context of the problem of the organization of high-quality nutrition for consumers, the ways of its solution by expanding the range of products based on raw fish materials are considered. The necessity of creating combined semi-finished products with adequate substitution for plant components is justified, which allows increasing the amount of dietary fiber consumed and reducing the caloric content of the product, enriching minced fish with carbohydrates (polysaccharides and dietary fibers), amino acids, as well as macro- and microelements. Thus, a comparative analysis of the content of essential amino acids in the muscle tissue of fish in the inland waters of the Republic of Kazakhstan with some oceanic and marine fish showed that the content of amino acids such as leucine, lysine, threonine, phenylalanine is slightly higher. They are characterized by a high content of essential amino acids limiting the biological value, g/100 g of protein: lysine – 8.8-11.6; methionine – 2.1-3.1; tryptophan – 1.0-1.1. The data analysis shows that a higher pH value of fish meat corresponds to a higher elasticity value. The pH shift to the alkaline side of more than 7.5, although it promotes the release of myosin, reduces the elasticity of meat. In our study, we used minced fish from Carp, Pikeperch, Bream, and Pike. It was found that with the addition of 30% of the functional supplement of kelp, the moisture-retaining capacity of the fish semi-finished product was 48.6% and pH 6.67. With the addition of 30% of the functional pumpkin additive, the moisture-retaining capacity of the fish semi-finished product was 49.27% and pH 6.04. Developing semi-finished fish products with plant components makes it possible to obtain products of high biological value with a juicy consistency, which meets modern trends in healthy nutrition.

Simulated In Vitro Digestive Characteristics of Raw Yam Tubers in Japanese Diet: Changes in Protein Profile, Starch Digestibility, Antioxidant Capacity and Microstructure

The consumption of raw yam tuber through grated yam "tororo" is a major and popular diet in Japan. However, few studies have been undertaken to evaluate the digestive characteristics of raw yam tubers. This study aimed to fill this gap by investigating the changes in the protein profile, protein and starch digestibility, antioxidant capacity and microstructure of two typical yam tubers (Nagaimo N-10 and Nebaristar) in the Japanese diet, applying a simulated in vitro digestion method. Results showed that both samples contained a considerable protein content of about 11% (dry basis) and a protein digestibility of 43-49%. The electrophoretic patterns confirmed that dioscorin was the main protein of the yam tuber, and it could be digested into peptides and free amino acids with low molecular weight during in vitro digestion. The starch hydrolysis results suggested that eating raw yam tuber cannot induce a fast glycemic increase for consumers due to a low starch digestibility of 4.4-6.1%. In addition, Nebaristar showed a higher bioaccessibility in some key amino acids and total phenolic content than the Nagaimo N-10. This study provides some essential nutritional information and simulated digestion behaviours of the raw yam tubers, which could be useful for consumers and industries when buying and processing yam tubers from the perspective of changes in the nutritional profile during digestion.

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.

Evaluation of the Thermophysical, Sensory, and Microstructural Properties of Colombian Coastal Carimañola Obtained by Atmospheric and Vacuum Frying

The quality of fried products affects consumer purchase decisions, and frying is an important stage in the production process. The objective of this research was to evaluate the thermophysical properties, the sensory quality, and microstructure of Colombian coastal Carimañola traditionally manufactured, in atmospheric frying and vacuum frying conditions. Lower moisture and fat content were reported in samples fried under vacuum compared to samples fried under atmospheric conditions, which is associated with the vacuum pressure during the process. Thermophysical properties, related to heat transfer in the samples, showed a correlation between thermal conductivity and moisture content. The micrographs visualized the changes in the porous structure of the coastal Carimañola. A greater effect was evidenced in the samples obtained by atmospheric frying because higher temperatures were used. The sensory evaluation reflected a preference for Carimañolas made with conventional frying. This research provides a basis for consumer purchases of traditionally fried products made with vacuum frying.

Impact of Low-Temperature Storage on the Microstructure, Digestibility, and Absorption Capacity of Cooked Rice

This study examined the effects of low-temperature storage on the microstructural, absorptive, and digestive properties of cooked rice. Cooked rice was refrigerated and stored at 4 °C for 0.5, 1, 3, 5, and 7 days, as well as frozen and preserved at −20, −40, and −80 °C for 0.5, 1, 3, 5, 7, 14, 21, and 28 days. The results indicated that the stored rice samples generally exhibited a higher absorption capacity for oil, cholesterol, and glucose than the freshly cooked rice. In addition, after storage, the digestibility of the cooked rice declined, namely, the rapidly digestible starch (RDS) content and estimated glycemic index (eGI) decreased, whereas the slowly digestible starch (SDS) and resistant starch (RS) content increased. Moreover, the increment of the storage temperatures or the extension of storage periods led to a lower amylolysis efficiency. Scanning electron microscopy (SEM) analysis indicated that storage temperature and duration could effectively modify the micromorphology of the stored rice samples and their digestion. Moreover, microstructural differences after storage and during simulated intestinal digestion could be correlated to the variations in the absorption capacity and digestibility. The findings from this study will be useful in providing alternative storage procedures to prepare rice products with improved nutritional qualities and functional properties.

Cooking methods affected the phytochemicals and antioxidant activities of potato from different varieties

•

Seven cooking methods were applied to cook potatoes from three varieties.

•

Cooking decreased the phytochemicals content and antioxidant activities of the potato.

•

Steaming and microwaving could remain more phytochemicals and antioxidant activities than other cooking methods.

In order to investigate the effect of different cooking methods on the phytochemicals and antioxidant activities of potato from different varieties, three varieties of potatoes were cooked with seven domestic methods. The contents of total phenolic, total carotenoid, vitamin C and phenolic acids of cooked potato were analyzed as well as the antioxidant activities. Results indicated that all the cooking methods showed negative effects on the contents of vitamin C, total phenolic, phenolic acids and DPPH radical-scavenging activity, but the effects were depended on the cooking methods, as frying, air-drying and roasting showed a more intensive decrease of total phenolic, phenolic acids and antioxidant activities than that of steaming or microwaving, regardless of the potato verities. From the perspective of remaining phytochemicals and antioxidant activities, Zhongshubahao might be an ideal potato sample and steaming or microwaving were optional methods for cooking potatoes.

Effects of Air Frying on French Fries: The Indication Role of Physicochemical Properties on the Formation of Maillard Hazards, and the Changes of Starch Digestibility

This study focused on the formation of Maillard hazards in air fried fries, highlighting the correlation between the resultant physical properties of the fries and the formation of Maillard hazards. In the meantime, the effects of air frying on the in vitro starch digestibility of fries were explored. Potato strips were fried at various temperatures (180-200°C) and time (12-24 min). Results indicated that the extent of browning, hardness, and the contents of Maillard hazards (acrylamide, 5-hydroxymethylfurfural, methylglyoxal, and glyoxal) all increased steadily with air frying temperature and time. Moisture content were negatively correlated (p < 0.001) with Maillard hazards content and physicochemical properties except for L^* with the correlation coefficients range from -0.53 to 0.94, and positively correlated with L^* value with correlation coefficient was 0.91, hence, reducing the Maillard hazard exposure while maintaining the desired product quality can be achieved by controlling the moisture content of the air fried French fries. Compared with deep frying (180°C-6 min), air frying decreased acrylamide and 5-hydroxymethylfurfural content with the maximum reduction rate were 47.31 and 57.04%, respectively. In addition, the in vitro digestion results suggested that air frying resulted in higher levels of slowly digestible starch (48.54-58.42%) and lower levels of resistant starch (20.08-29.34%) as compared to those from deep frying (45.59 ± 4.89 and 35.22 ± 0.65%, respectively), which might contribute to more balanced blood sugar levels after consumption. Based on the above results, it was concluded that air frying can reduce the formation of food hazards and was relatively healthier.

Effect of air fryer frying temperature on the quality attributes of sturgeon steak and comparison of its performance with traditional deep fat frying

In this study, the influence of air-frying temperature on the physical properties of sturgeon steaks was explored. Meanwhile, the comparison of traditional deep fat frying (TF) and air fryer frying (AFF) methods on the quality, flavor, and digestibility of sturgeon steaks were investigated. The results indicated that along with the increase of temperature (130, 160, and 190℃) for 15 min, the moisture content of AFF sturgeon steak surface decreased dramatically while that of interior was well preserved. The applied texture property analysis exhibited that AFF sturgeon steak showed the enhanced elasticity, low hardness, and soft texture. The results indicated that AFF sturgeon steak contained higher essential amino acid content than TF sturgeon steak. More flavor compounds (aldehydes, alcohols, and esters) were produced after AFF than TF. Although the digestibility of fried sturgeon steaks decreased after frying, AFF sturgeon steaks were digested rapidly in the stomach and intestine. Conclusively, AFF sturgeon steaks exhibited a crispy texture, appealing flavor, and low oil content. This work provides a certain reference for the suitable frying methods in the processing industry of sturgeon products.

Effect of New Frying Technology on Starchy Food Quality

Frying is commonly used by consumers, restaurants, and industries around the globe to cook and process foods. Compared to other food processing methods, frying has several potential advantages, including reduced processing times and the creation of foods with desirable sensory attributes. Frying is often used to prepare starchy foods. After ingestion, the starch and fat in these foods are hydrolyzed by enzymes in the human digestive tract, thereby providing an important source of energy (glucose and fatty acids) for the human body. Conversely, overconsumption of fried starchy foods can promote overweight, obesity, and other chronic diseases. Moreover, frying can generate toxic reaction products that can damage people's health. Consequently, there is interest in developing alternative frying technologies that reduce the levels of nutritionally undesirable components in fried foods, such as vacuum, microwave, air, and radiant frying methods. In this review, we focus on the principles and applications of these innovative frying technologies, and highlight their potential advantages and shortcomings. Further development of these technologies should lead to the creation of healthier fried foods that can help combat the rise in diet-related chronic diseases.

Understanding the Properties of Starch in Potatoes (Solanum tuberosum var. Agria) after Being Treated with Pulsed Electric Field Processing

The purpose of this study was to investigate the properties of starch in potatoes (Solanum tuberosum cv. Agria) after being treated with pulsed electric fields (PEF). Potatoes were treated at 50 and 150 kJ/kg specific energies with various electric field strengths of 0, 0.5, 0.7, 0.9 and 1.1 kV/cm. Distilled water was used as the processing medium. Starches were isolated from potato tissue and from the PEF processing medium. To assess the starch properties, various methods were used, i.e., the birefringence capability using a polarised light microscopy, gelatinisation behaviour using hot-stage light microscopy and differential scanning calorimetry (DSC), thermal stability using thermogravimetry (TGA), enzyme susceptibility towards α-amylase and the extent of starch hydrolysis under in vitro simulated human digestion conditions. The findings showed that PEF did not change the properties of starch inside the potatoes, but it narrowed the temperature range of gelatinisation and reduced the digestibility of starch collected in the processing medium. Therefore, this study confirms that, when used as a processing aid for potato, PEF does not result in detrimental effects on the properties of potato starch.