Effect of processing procedure on the formation of resistant starch in tamales

Agave inulin as a fat replacer in tamales: Physicochemical, nutritional, and sensory attributes

Tamales are a traditional dish rich in fat and carbohydrates with increasing popularity. The present study aimed to investigate the use of agave inulin powder (AIP) as a potential fat replacer in tamales. The effect of replacing 0%, 33%, 66%, and 100% (w/w) of fat with AIP was evaluated in the physicochemical, sensory, and nutritional features of tamales. The fat content of tamales decreased up to 88% in AIP tamales, whereas total dietary fiber (TDF) increased up to 14%. TDF in AIP tamales had a higher proportion of soluble dietary fiber (SDF). Moreover, results indicated that both insoluble and SDF were formed during the processing of tamales. Fat replacement led to a reduction of up to 26% in the calorie load of tamales. Fourier transform infrared spectroscopy analysis confirmed changes in the absorption bands related to carbohydrates, with increments in peaks associated with inulin (936 and 862 cm-1 ), and inhibition of retrogradation when inulin was included. AIP addition resulted in tamales with lighter color. Fat replacement with AIP affected the texture of tamales increasing their softness, adhesiveness, and cohesiveness. In general, inulin positively affected the hedonic attributes and acceptance of tamales. Interestingly, full-fat tamales had a lower glycemic index and presented higher contents of resistant starch compared to tamales with AIP. Nevertheless, agave inulin may serve as a fat replacer yielding reduced-fat tamales with higher TDF and SDF and yielding a lower calorie load without significantly affecting the sensory acceptability of this traditional meal.

Storage temperature and time affect the enzyme resistance starch and glycemic response of cooked noodles

White-salted noodles are prepared, stored and consumed in various ways. However, relationships among cooking and storage conditions on nutritional functionality are not fully understood. The manuscript elucidates the mechanism of formation of resistant starch (RS) leading to slower digestion rate of variously cooked (boiled, steamed, stir-fried, fried and microwave heated) noodles followed by storage under different conditions (-18, 4 and 25 °C for 4, 24 and 48 h). RS content of noodles stored at 25 °C was higher than noodles stored at 4 °C, which was consistent with increases in the degree of crystallinity during storage. We showed that the residual moisture content primarily facilitated the mobility of starch chains and contributed towards the increase in RS associated with the decrease of enzyme susceptivity of noodles after storage. Evidence that supramolecular organization (helical structure and crystallinity) had a more pronounced effect than the macroscopic structure such as compactness or bulk density was also provided.

Physicochemical Properties and Resistant Starch Content of Corn Tortilla Flours Refrigerated at Different Storage Times

The tortilla is a foodstuff that has a short shelf-life, causing great losses to the industry. The objective of this work was to evaluate, for the first time, the physicochemical properties and resistant starch (RS) content of flours. These were obtained from nixtamalized corn tortillas made with traditional and industrial (commercial) methods, stored at 4 °C for 7, 15, and 30 days. The flours were characterized by measuring particle size distribution, color, water absorption index (WAI), water solubility index (WSI), viscosity, calcium, and RS content. Additionally, chemical proximate analysis, scanning electron microscopy (SEM), and thermal analysis were conducted. Storage at 4 °C increased the friability of tortillas and shifted the particle size distribution toward a greater content of coarse particles in corn tortilla flours. The commercial corn tortilla flours showed higher WAI and WSI values than the traditional corn tortilla flours. On the other hand, the traditional corn tortilla flours exhibited higher RS content values than commercial corn tortilla flours as well as peak viscosity. X-ray diffractograms revealed the presence of amylose-lipid complexes (RS5) in experimental samples. The thermograms evidenced three endotherms corresponding to corn starch gelatinization and melting of type I and type II amylose-lipid complexes.

RS Content and eGI Value of Cooked Noodles (I): Effect of Cooking Methods

Noodles are widely consumed in China, which can be cooked in different ways. The effects of different cooking methods (boiling, steaming, microwave heating, stir-frying and frying) on the resistance starch (RS) content and digestive properties (digestion rate, digestibility and estimated glycemic index (eGI) value) of noodles were investigated. The RS content was greatly affected by the cooking time, and it was varied when the noodles were optimally cooked using different cooking methods. The RS contents of the microwaved and stir-fried noodles were relatively high (0.59%-0.99%), but it was lower (0.43%-0.44%) in the boiled and steamed noodles. Microwaved noodles showed the slowest digestion rate and the lowest eGI. Due to the limited water within fried noodles, none RS was found in the fried noodles, whereas stir-fried noodles showed RS5 formation from the XRD and DSC results. Compared with boiled and steamed noodles, the microwaved noodles showed a more compact morphology without porous holes on the surface, whereas fried noodles showed irregular morphology. The results indicated that the digestive properties of noodles made with the same ingredients can be greatly altered by using different cooking methods, and the digestive properties of different cooked noodles are worthy of confirmation using in vivo analysis.

A novel, simple, economic and effective method for retarding maize tortilla staling

BACKGROUND

Staling of maize tortillas is a major drawback affecting their manufacture, commercialization and consumption. The development of methods that may help retard staling of maize tortillas is an ongoing research topic. In this work, a novel, simple, economic and effective method is proposed, based on adding completely gelatinized nixtamalized maize flour (GMF) dispersion to the basic masa formulation recipe (water, 600 g kg^-1 ; nixtamalized maize flour, 400 g kg^-1 ) in substitution of 50, 100 and 150 g kg^-1 of water.

RESULTS

Masa added with GMF showed increased water retention capacity, reduced freezable water content and improved flow and dynamic rheological properties and produced tortillas with decreased firmness. The infrared 1047/1022 cm^-1 spectral ratio indicated that a more disordered starch granule arrangement was formed, while enthalpy peaks associated with starch retrogradation decreased. All the above indicators were more pronounced the higher was the GMF content.

CONCLUSION

This work showed that GMF can play the role of a self-hydrocolloid anti-staling agent by retarding the retrogradation of maize starch and deterring the loss of water and rheological properties of masa and the increase in undesirable sensory characteristics of tortilla such as increased firmness. © 2018 Society of Chemical Industry.

Nixtamalization Process Affects Resistant Starch Formation and Glycemic Index of Tamales

Tamales were prepared with 3 nixtamalization processes (traditional, ecological, and classic) and evaluated for chemical composition, starch properties, and glycemic index. Resistant starch (RS) in tamales increased 1.6 to 3.7 times compared to raw maize. This increment was due to the starch retrogradation (RS3) and amylose-lipid complexes (RS5) formation. Tamales elaborated with classic and ecological nixtamalization processes exhibited the highest total, soluble and insoluble dietary fiber content, and the highest RS content and lower in vivo glycemic index compared to tamales elaborated with traditional nixtamalization process. Thermal properties of tamales showed 3 endotherms: amylopectin retrogradation (42.7 to 66.6 °C), melting of amylose lipid complex type I (78.8 to 105.4), and melting of amylose-lipid complex type II (110.7 to 129.7). Raw maize exhibited X-ray diffraction pattern type A, after nixtamalization and cooking of tamales it changed to V-type polymorph structure, due to amylose-lipid complexes formation. Tamales from ecological nixtamalization processes could represent potential health benefits associated with the reduction on blood glucose response after consumption.