Bread crispness and morphology can be controlled by proving conditions

Bread crust crispness is lost when water migrates from crumb to crust during storage. To what extent water migration is influenced by morphology is not known. Therefore, the effect of crispy rolls morphology on crust crispness was studied. Crispy rolls were prepared at three proving volumes: 300 mL (short proving), 500 mL (control) and 800 mL (long proving). X-ray microtomography was used to characterize morphology.Water transport from crumb to crust was determined. Short proved crispy rolls showed lower rate of crust water uptake while longer proved rolls showed faster uptake during cooling down. Sensory analysis revealed higher crispness for short proved crispy rolls after the same storage time at low RH. We hypothesize that shorter proved crispy rolls with finer crumb morphology, more closed structure, smaller gas cells with less gas cells interconnections and a thicker crust have a significant positive effect on water uptake kinetics and crispness retention.     

Performance of cellulose derivatives in deep-fried battered snacks: Oil barrier and crispy properties

The performance of batters containing cellulose derivatives (methyl cellulose (A4M), three hydroxypropylmethyl celluloses (E4M, F4M and K4M) with different degree of hydroxypropyl and/or methyl substitution and carboxymethyl cellulose (CMC)) to produce crispy deep-fried snacks crusts was studied by using a deep-fried crust model. Their performance was compared in terms of their ability to retain moisture content, to decrease oil content and the effect on crispness. Thermogelation properties of the cellulose derivatives depended on the type and degree of substitution. All increased the water content and decreased the oil content of the deep-fried crusts, except for CMC, which does not thermogelate and did not increase the amount of water retained in the crust, although a decrease in the oil content was found. The highest oil reduction and the lowest water retention were found for the cellulose with the lowest level of methyl substitution (K4M). The sound emitted during fracture of K4M crusts had higher intensity than the other cellulose derivatives indicating a crispier crust.     

Characterization of crispness of French fries by fracture and acoustic measurements,effect of pre-frying and final frying times

The influence of pre-frying and final frying time on the crispness of French fries was evaluated by simultaneous analysis of the fracture and acoustic properties during instrumental simulation of human chewing. The analysis of the frequency distribution of the force and sound events corresponding to the crust of the French fry reflected an effect of both pre-frying and final frying time on instrumental crispness. Up to 60 s pre-frying, an increase in the number and magnitude of force and sound events was found, which reflect an increase in crispness. The increase in final frying time increased crispness, but it cannot counterbalance a lack of pre-frying. The moisture content of the whole French fries cannot explained the effect of pre-frying on crispness. Conversely, the effect of pre-frying can be explained when considering only the moisture content of the crust. Pre-frying may allow an easier loss of water from the crust during final frying, which will enhance its crispness.     

Crust morphology and crispness development during deep-fat frying of potato

Crust formation is an important factor in determining the crispness of French fries. This study aimed at unravelling detailed structural and textural properties of the crust in relation to crispness during frying as a function of the process temperature and time. X-ray tomography showed a larger overall pore volume at higher frying times, while a lower final moisture content mainly resulted in an increase in the amount of large pores. Texture analysis revealed that the increase in porosity, due to the increased formation of pores, results in a more crispy behaviour after frying with oil of up to 180 °C. At temperatures above 180 °C crispness is actually found to decrease again, which is explained by the increased plastic behaviour of the crust. This may be related to the reduced glass transition temperature of the crust because of increased sugar degradation at a very high temperature.     

Effects of ultrasound pretreatments on the kinetics of moisture loss and oil uptake during deep fat frying of sweet potato (Ipomea batatas)

The possibility of ultrasound assisted pretreatments of sweet potato to lower the moisture content and oil uptake during deep fat frying and its effects on the mass transfer rate was investigated. Sweet potato samples prior to frying were immersed in distilled water with ultrasound (UD), osmotic dehydration without ultrasound (OD) and ultrasound assisted osmotic dehydration (UOD). Ultrasound probe having frequency of 28 kHz at 300 W maximum power and time of 30 min was used for the pretreatment. The control (without pretreatment) and the pretreated samples were fried using sunflower oil at temperature of 130, 150 and 170 °C for 2, 4, 6, 8 and 10 min. The first order kinetic model was used for the mass transfer rate for moisture loss and oil uptake. The lowest moisture content was found in fried samples pretreated in UOD and OD while the lowest oil uptake was obtained in fried samples pretreated in UD having 65.11 and 71.47% oil reduction at temperature of 150 and 170 °C, respectively, compared to the untreated sample. The k values of all pretreated samples were higher than that of the untreated at 150 and 170 °C. The highest activation energy for moisture loss was found in untreated samples while the lowest activation energy for oil uptake was found in samples pretreated in UOD. The results from this work proved that ultrasound is a good pretreatment that can be used to obtain a low moisture content and oil uptake during deep fat frying of sweet potato.Industrial relevanceUltrasound is a novel technology that is widely used in the food industries because of its numerous advantages over conventional methods. Its application in the frying of foods could also help in the reduction of oil uptake, thus making safe the consumption of fried foods. The information about frying kinetics could also help in the design and optimization of the process in the food industry.     

CRISPY/CRUNCHY CRUSTS OF CELLULAR SOLID FOODS: A LITERATURE REVIEW WITH DISCUSSION

Literature on the crispy/crunchy behavior of cellular solid foods with a crust is discussed. The emphasis is on products with a dry crispy or crunchy crust as bread and various snacks and especially on mesoscopic and macroscopic aspects. Successively, the sensory sensations involved, the mechanical and fracture behavior of crispy/crunchy products, morphological aspects, and the relation between crispy and crunchy behavior and mobility of the macromolecules and plasticizer (primarily water) involved, are discussed. Finally, some ideas for an integrated approach of crispy/crunchy behavior of cellular solid foods with a dry crust will be discussed.     

Crystallization of NaCl by fast evaporation of water in droplets of NaCl solutions

Excessive salt (NaCl) intake has been related to several diseases. Small salt crystals that rapidly dissolve in the oral cavity may decrease swallowing of untasted salt. The aim of this research was to evaluate the crystallization of salt as microcrystals by fast water evaporation from droplets of saline solutions within a hot oil phase. The effects of the oil temperature (150; 165 and 180 °C), droplet volume (17 and 42 μL) and brine concentration (15 and 26% w/v) were studied. Crystalline particles with mean sizes between 9 and 23 μm, and containing about 2% of remaining oil were obtained. The crystal size decreased by increasing the oil temperature, solution concentration and volume of the droplets. The dissolution rate of these microcrystals was more than 2 times faster than that of the original crystals. The microcrystals obtained could be added in surface-salted foods (snacks, salads) to optimize or reduce the sodium intake while maintaining saltiness perception.     

Investigation of the formation of (E)-2-butenal in oils and foods during frying

The formation of (E)-2-butenal in oils subjected to temperatures applied in frying as well as in fried foods was evaluated. For this purpose, a sensitive and accurate stable isotope dilution essay was developed and validated using as an internal standard (E)-2-butenal d6 synthesized in the lab. Heating of corn oil, sunflower oil, extra virgin and refined olive oil, ω-3 frying oil and palm oil at 170 °C for a total of 8 h resulted in the formation of (E)-2-butenal at levels between 0.05 and 1 μg g^− 1 and the highest amounts were already formed after 2 h of heating. The highest (E)-2-butenal formation was observed in the oil containing ω-3 unsaturated fatty acids indicating that (E)-2-butenal content is mainly affected by the fatty acid composition. No significant amount of free (E)-2-butenal was detected in fried foods purchased from fast food shops with the exception of one chicken sample and a pork brochette. Further experiments including several foods did not indicate any increase of free (E)-2-butenal content due to frying. It can be suggested that fried foods may not be a significant dietary source of free (E)-2-butenal for humans. However, these results in combination with the available literature indicated that investigation of the contamination of the indoor environment where frying is taking place could be more relevant than the presence of free (E)-2-butenal in oils and foods.     

Effect of processing conditions on the stability of annatto (Bixa orellana L.) dye incorporated into some foods

Annatto dye is an orange-yellow pigment extensively used in dairy products. Studies were carried out to determine the stability of bixin (oil-soluble dye) during different treatments and processing in traditional foods of India. The annatto dye was exposed to heat treatments in a baking oven at 100, 150 and 180 °C for time periods up to 60 min; deep fat heating at 160, 180 and 200 °C for periods ranging from 30 to 120 s; microwave oven at 300 and 700 W for periods ranging from 15 to 60 s; and in a pressure cooker for a 15-min period. The losses in bixin concentration during these experiments were compared with the losses of bixin in the preparation of products like cakes, chegodis, biscuits and fried rice. The mass fractions of bixin lost were maximum when the dye was exposed directly to heating in a baking oven (0.54) and in deep fat heating (0.47). The mass fraction of bixin lost was 0.30 in cakes and negligible losses were observed in biscuits (0.015). In case of the deep fat fried snack, the dye leached in to the oil, which resulted in maximum loss (0.65). Microwaves did not affect the bixin in the dye when exposed directly or in the products. Pressure cooking resulted in mass fractions of bixin lost (0.25–0.33) comparable to those of other products.     

Influence of addition of green tea and green coffee extracts on the properties of fine yeast pastry fried products

This study investigated the influence of antioxidants of green tea aqueous extract (GTE) and green coffee aqueous extract (GCE) in concentrations of 0.25, 0.5 and 1 g·100 g^? 1 on the nutritional properties of fine yeast pastry fried products such as donuts. Yeast donuts were made according to the traditional processing technology. In fried donuts physical properties (water activity, pH, hardness and color with the use of instrumental methods) as well as sensory properties were established. Moreover, quality of fat extracted from donuts (composition of fatty acids and peroxide value), content of acrylamide, composition of polyphenols and antioxidant activity were analyzed. Obtained extracts of GTE and GCE contained 26 and 41% of polyphenols, respectively, and the degree of polyphenol degradation during production of donuts was less when the dilution in dough was greater. Both tests indicated that the highest antioxidant activity had donuts with the highest analyzed addition of extract, however depending on the applied test or GTE or GCE had better antioxidant properties. Fatty acid composition was the most beneficial when the addition of GTE and GCE was on a level of 0.25 and 0.5 g·100 g^? 1, respectively. In fried donuts relatively low amounts of acrylamide were obtained, amounting to 18–46 μg·kg^? 1. Only the lowest addition of GTE and the highest addition of GCE caused an increase of acrylamide content in donuts, while all other levels of added extracts caused a decrease in the content of formed acrylamide.     

What are domestic apples worth? Hedonic responses and sensory information as drivers of willingness to pay

The effects of written information of key sensory characteristics of apple cultivars on hedonic ratings and willingness to pay (WTP) were measured in an experimental auction. Participants (n = 118, 95F, 23M, mean age 37 y.) rated, in three subsequent rounds, pleasantness and WTP based on (1) appearance only (n = 25), (2) appearance, written information and tasting (n = 44), or (3) appearance, tasting and written information (n = 49). Four domestic cultivars were described as medium sour and crispy (‘Amorosa’), sour and medium crispy (‘Konsta’), medium sweet and medium crispy (‘Lobo’) and sweet and medium crispy (‘Tobias’). The differences between the cultivars in pleasantness and WTP were minimal when the evaluation was based on appearance only. The effect of tasting after visual inspection was positive in three cultivars and negative in one (‘Konsta’). Written information after tasting did not affect pleasantness or WTP. For one cultivar (‘Tobias’), information given before tasting created expectations that were not fulfilled, thus tasting decreased hedonic ratings and WTP. Mean WTP was 2.36 euro/kg. When pleasantness increased by one point, WTP increased by 0.31–0.45 euro/kg. Regression models showed that pleasantness explained 38–55% of WTP. Respondents who reported consuming domestic apples more often than once a week had 0.52–0.74 euro/kg higher WTP than those who consumed them less frequently, suggesting that familiarity with the product increases WTP. Results indicate that both written information and tasting contribute to the ratings of pleasantness and WTP.     

Effect of processing conditions on the structure of monostearin–oil–water gels

The effect of processing conditions on the formation and stability of a gel comprised of oil, water, monostearin and stearic acid was studied. Processing conditions (homogenization rate (10,000–30,000 rpm), cooling rate (0.05–20 °C/min), homogenization temperature (70–95 °C)) had no effect on the initial storage modulus and melting temperature of the gel. Salt (NaCl) addition to the aqueous phase in the range 0–0.25% did not affect these parameters either; however, 0.5% salt addition lead to a ∼2 °C decrease in melting temperature and a doubling of the storage modulus. Optimal preparation conditions for the gel were mainly determined from its microstructure by polarized light microscopy – a smaller globule size and a more homogenous size distribution were considered a desirable feature. Optimum conditions included homogenization rates greater than 20,000 rpm, cooling rates above 6 °C/min, homogenization temperatures above, but close to, the Krafft temperature of monostearin (72 °C), and 0% salt concentration. The gelation temperature decreased by 2 °C with each 1 °C/min increase in cooling rate, from 1 °C/min to 5 °C/min.     

INFLUENCE OF WATER ON THE CRISPNESS OF CEREAL-BASED FOODS: ACOUSTIC, MECHANICAL, AND SENSORY STUDIES

The texture properties of crispy breads were studied as a function of water content using compression tests, acoustic measurements and sensory analysis. The addition of water slowly lowers the characteristics associated with crispness up to 9%, after which they steeply decrease. Dynamic Mechanical Thermal Analysis (DMTA) measurements were carried out, at room temperature and at 5 Hz, on the same bread samples. The evolution of the textural properties of crispy bread are accompanied by an increase of the loss factor prior to the one associated to the glass transition. It was therefore proposed that the effect of water on the brittle character, on crispness and on the intensity of the sound emitted at fracture were due to the onset of molecular motions preceding or accompanying the glass transition.     

Effect of green tea extract and microwave pre-cooking on the formation of acrylamide in fried chicken drumsticks and chicken wings

Since 2002, it has been well-known that carbohydrate-rich foods have a high level of acrylamide (AA). Some researchers have drawn attention on the formation of AA in coated and fried chicken meat products in recent years. From this viewpoint, the purpose of the present study was to mitigate acrylamide formation in fried chicken drumsticks (CDs) and chicken wings (CWs) using green tea extract (GTE) alone or combined with microwave pre-cooking (MPC) by decrease frying time. In brief, CDs and CWs marinated for one day were divided into eight groups. Four of those were first covered with batter and breading, including 0%, 0.5%, 1.5% and 3% GTE and deep fried in fat for 8.5 min for CDs and 3.5 min for CWs at 175 °C and 8 psi of pressure. In the second step, the remainder of the marinated CDs and CWs were subjected to MPC for 7 min and 5 min, respectively. Then, they were covered with batter and breading including 0%, 0.5%, 1.5% and 3% GTE and deep fried in fat for 5.5 min for CDs and 2.5 min for CWs at 175 °C and 8 psi for pressure. With increasing levels of GTE, the AA concentration decreased gradually in CDs and CWs. In addition, MPC also decreased AA formation in CWs due to the shorter frying time. Moreover, MPC was more efficient at reducing AA formation in CWs when it was combined with GTE. A lighter and more yellowish color was measured in CDs as a consequence of the shorter frying time. It is crucial to state that the incorporation of GTE into the breading or MPC did not negatively affect the sensory properties of CDs and CWs, while it reduced AA formation. In conclusion, it can be stated that GTE alone or combined with MPC is an effective and practical mitigation strategy for AA formation.     

Heat transfer coefficients during deep fat frying of sweetpotato: Effects of product size and oil temperature

Heat transfer coefficient, h during deep fat frying of sweetpotato was determined from designed experiments. Samples of three different disc sizes were fried at four oil temperatures between 150 and 180 °C. Heat transfer coefficient estimation was based on heat energy balance between the oil and sample during frying. Maximum h was reached at the earlier stage of frying (80–120 s). The range of maximum h reached was 710–850 W/m² °C. h at latter period of frying (200–300 s) was 450–550 W/m² °C. h was found to vary directly with oil temperature but inversely with sample size (p <0.05).     

Human Serum Vitamin A and β-Carotene Contents in Relation to Locally Consumed Foods,Social Status and Gender in Kano Metropolis

Determination of the levels of vitamin A (as retinol) and β-carotene in locally consumed foods in relationship to their occurrence in the serum of individuals grouped according to different social groups and sexes was carried out in Kano metropolis. Both raw and prepared foods (meals/snacks) investigated showed the presence of β-carotene while vitamin A was only present in the latter. The levels of β-carotene in foods/snacks ranged from 2.00 – 3.40 and 88 – 1120 iu/kg in raw foods while that of vitamin A in the former was 13.00 – 23.50 iu/kg. Food/snacks derived from animal products and those made from vitamin A fortified foods showed marginally higher vitamin contents. The mean serum β-carotene and retinol concentrations of the individual grouped according to sex and social class showed significant differences between the three social groups (P < 0.05). The higher the income class, the higher the value of vitamin A and its precursor. There was no significant difference in the β-carotene and retinol concentration between males and females of low income and high income class (P > 0.05). However, there was significant difference between males and females of the medium income class (P < 0.05). These results are discussed in terms of an apparent relationship between income and serum vitamin A content.     

Carbohydrate composition of raw and extruded pulse flours

Extrusion cooking technology is commercially used in the fabrication of a variety of snack-type and ready-to-eat foods made from cereal grains. However, with the exception of soybean, pulses such as lentil, dry pea and chickpea have not been used for the development of extruded food products. In this study, total carbohydrates, mono-, di- and oligosaccharides, and soluble and insoluble dietary fiber were determined before and after extrusion cooking under specific processing conditions. Concentrations of total available carbohydrates (TAC) in lentil, chickpea and dry pea flours ranged from 625 g/kg to 657 g/kg dry matter. Dry pea showed the highest concentration of TAC, followed by chickpea and lentil. Extrusion processing did not significantly (p < 0.05) affect the TAC content of dry pea and lentil flours. However, extrusion processing decreased the concentration of the raffinose family of oligosaccharides (raffinose and stachyose) in pulse extrudates. Formulated pulse flours demonstrated a beneficial increase in dietary fiber. This research indicates that value-added, nutritious snacks with reduced levels of flatulence factors and higher contents of dietary fiber can be fabricated successfully by extrusion processing of formulations based on lentil, dry pea or chickpea, and represent good alternatives to traditional cereal-based snacks. Also, the commercialization of value-added, pulse-based snacks would increase pulse consumption.     

4种亲水多糖对油炸调理鸡排品质的影响

亲水多糖常被用来改善即食类油炸产品的质量.针对油炸调理类产品含油量高的问题,通过向油炸调理鸡排外裹糊中添加黄原胶、海藻酸钠、羟丙基甲基纤维素和魔芋胶4种亲水多糖,探究亲水多糖对二次油炸调理鸡排品质(水分含量、油分含量、色泽、脆性、可冻结水含量及感官评价)的影响.结果 表明:与对照组相比,添加4种亲水多糖可以显著提升油炸...     

Carotenoid transfer to oil during thermal processing of low fat carrot and tomato particle based suspensions

Carotenoid solubilization in the oil phase is a prerequisite for carotenoid bioaccessibility during digestion. However, the level of bioencapsulation and the hydrophobicity of carotenoids were proven to strongly affect their transfer to oil during in vitro digestion. Therefore, thermal processing (95–110 °C) was exploited to favor carotenoid transfer from tomato- and carrot-based fractions to the oil before digestion. Initially, the total (all-trans + cis) carotenoid content in the oil increased quickly, thereafter, depending on the temperature applied, either a drop or a plateau was reached at longer treatment times. Treatment conditions of > 100 °C for 10 min significantly favoured carotenoid transfer to oil (≥ 75%). The rates of transfer to oil were as follows: β-carotene ≈ α-carotene > lycopene. The results revealed that the cell wall hinders carotenoid transfer to oil during thermal processing. Overall, the results indicate that typical high temperature short time thermal processing can be sufficient to achieve maximal carotenoid transfer to oil with minimal degradation in real food systems/food emulsions and this can be crucial to improve the nutritional quality of carrot and tomato based products.