Frederico Augusto Ribeiro de Barros

Interaction of tannins and other sorghum phenolic compounds with starch and effects on in vitro starch digestibility.

This study investigated interactions of sorghum proanthocyanidins (PAs) with starch molecules and the effect on in vitro starch digestibility. High tannin (predominant in PA), black (monomeric polyphenols), and white (low in polyphenols) sorghum phenolic extracts were mixed and cooked with starches varying in amylose content. Starch pasting properties, polyphenol profile, and resistant starch (RS) were determined. PAs decreased setback of normal starch and were least extractable after cooking with all starches. Pure amylose interacted more strongly with oligomeric and polymeric PA compared to amylopectin. The PA extract increased the net RS in normal starch by about 2 times more than the monomeric polyphenol extract; debranching amylopectin increased the difference by 4.3 times. Only treatments with PA increased RS in high amylose starch (52% higher than the control). Sorghum PAs interact strongly with starch, decreasing starch digestibility. The interactions appear to be specific to amylose and linear fragments of amylopectin, suggesting hydrophobic interactions are involved.

Effect of molecular weight profile of sorghum proanthocyanidins on resistant starch formation

BACKGROUND There is a growing interest to increase resistant starch (RS) in foods through natural modification of starch. Sorghum tannins (proanthocyanidins, PAs) were recently reported to interact with starch, increasing RS. However, there is no information about how the molecular weight profile of PAs affects RS formation. This study investigated how different-molecular-weight PAs from sorghum affected RS formation in different starch models. RESULTS The levels of RS were higher (331-437 mg g(-1)) when high-amylose starch was cooked with phenolic extracts containing mostly high-molecular-weight PAs compared with extracts containing lower-molecular-weight PAs or monomeric catechin (249-285 mg g(-1)). In general, binding capacity of PAs with amylose increased proportionally with molecular weight. For example, the percentage of PAs bound to amylose increased from 45% (PAs with degree of polymerization (DP) = 6) to 94% (polymeric PAs, DP > 10). The results demonstrate that molecular weight of the PAs directly affects their interaction with starch: the higher the molecular weight, the stronger the binding to amylose and the higher the RS formation. CONCLUSION Polymeric PAs from sorghum can naturally modify starch by interacting strongly with amylose and are thus most suitable to produce foods with higher RS.

Effect of Oxygen‐Absorbing Packaging on the Shelf Life of a Liquid‐Based Component of Military Operational Rations

Oxygen within the sealed package can reduce the quality of liquid-based food products with high oil content such as hot-filled meal-ready-to-eat (MRE) cheese spread, a component of military operational rations. The aim of this study was to test a novel oxygen absorber-containing laminate material and its ability to maintain and/or extend shelf life of a cheese-spread MRE item. An iron-based oxygen absorber (ABSO(2)RB(R)) activated by moisture was incorporated into the laminate and used to pack hot-filled cheese spread MREs. The kinetics of oxygen absorption due to humidity and temperature were characterized and peel tests performed to ensure pouch seal integrity. Accelerated shelf-life tests of ABSO(2)RB and regular MRE pouches without the O(2)-absorber were conducted for 3 mo at 51.7 degrees C (125 degrees F), and 6 mo at 37.8 degrees C (100 degrees F) by measuring oxygen concentration (Mocon O(2)-analyzer), microbiological, and physicochemical quality characteristics, including color, texture, moisture, free fatty acid (FFA), pH, water activity, and vitamins and A. Pouches stored at 26.7 degrees C (80 degrees F) for 12 mo served as calibrated controls. Consumer tests were conducted in-house and a confirmatory sensory test was conducted at Natick by a trained panel using a 9-point hedonic scale. ABSO(2)RB-laminates maintain the same seal integrity and strength as those of the control samples. The headspace oxygen concentrations in these pouches reached (P < 0.05) < 0.5% in 11 d of storage at 26.7 degrees C (80 degrees F) and remained below this level throughout the storage period (1 y). No microbial growth (aerobic, coliforms, yeast, and molds) was detected (P < 0.05) for both packages. Overall, the ABSO(2)RB-pouches indicate an improved reduction in oxygen and vitamin C retention compared with MRE controls and maintained product quality (physicochemical and organoleptic). ABSO(2)RB-laminates met the accelerated shelf-life requirement of 1 mo at 51.7 degrees C (125 degrees F), and 6 mo at 37.8 degrees C (100 degrees F). This study clearly shows the benefits of using active packaging technology on retaining nutrition and prolonging shelf life of high-fat, liquid content MRE items.

Effect of the storage time and temperature on phenolic compounds of sorghum grain and flour.

This study evaluated the effect of storage temperature (4, 25 and 40°C) and time on the color and contents of 3-deoxyanthocyanins, total anthocyanins, total phenols and tannins of sorghum stored for 180days. Two genotypes SC319 (grain and flour) and TX430 (bran and flour) were analyzed. The SC319 flour showed luteolinidin and apigeninidin contents higher than the grain and the TX430 bran had the levels of all compounds higher than the flour. The storage temperature did not affect most of the analyzed variables. The content of most of the compounds reduced during the first 60days when they became stable. At day 180, the retention of the compounds in the genotypes SC319 and TX430 ranged from 56.1-77.9% and 67.3-80.1% (3-deoxyanthocyanins), 88.4-93.8% and 84.6-96.8% (total anthocyanins) and 86.7-86.8 and 89.4-100% (phenols) respectively. The retention of tannins ranged from 56.6 to 85.3%. The color of samples remained stable for 120days.

Camu-camu (Myrciaria dubia) from commercial cultivation has higher levels of bioactive compounds than native cultivation (Amazon Forest) and presents antimutagenic effects in vivo : Commercial camu-camu as functional food

BACKGROUND Camu-camu (Myrciaria dubia) is a typical Amazonian fruit and has high antioxidant capacity due to its high levels of vitamin C and phenolic compounds. This study aimed to determine the phytochemicals, antioxidant capacity and antimutagenic effects of camu-camu fruits with different maturity stages grown in dry (commercial cultivation) or flooded environments (native cultivation, Amazon). RESULTS Total polyphenols, ascorbic acid and in vitro antioxidant capacity levels were higher in ripe fruits grown in a commercial cultivation. The extracts from ripe camu-camu grown in a commercial cultivation exerted antioxidant effects and high percentage of protection against doxorubicin and 1,2-dimethylhydrazine in all tested systems (liver, bone marrow and gut), for three camu-camu extract concentrations (17, 85 and 170 mg kg-1 body weight), as follows: bone marrow minocronucleus (37.91%, 41.75%, 43.95%); micronucleus gut test (61.01%, 64.40%, 50.28%); apoptosis index (60.26%, 62.44%, 58.22%); comet assay through the tail moment (71.64%, 72.31%, 70.70%), percent DNA in the tail (64.54%, 68.75%, 76.79%) and tail intensity (76.43%, 81.02%, 68.33%). CONCLUSION The results of this study contribute to increasing the production of camu-camu fruits grown in dry environments and their use as a health-promoting food.

Increased thermal stability of anthocyanins at pH 4.0 by guar gum in aqueous dispersions and in double emulsions W/O/W

This study investigated the potential of guar gum and a double emulsion to increase the thermal stability of anthocyanins. The effect of different guar gum concentrations (0%, 0.25%, 0.50%, 0.75%, 1%, 1.25%, 1.5% and 1.75%) was evaluated in relation to color stability, concentration of anthocyanins and antioxidant capacity under storage for 10 days at 40 °C in the presence of light. The addition of guar gum (0.75-1.75%) significantly increased the color stability and bathochromic displacement of the samples, suggesting the occurrence of a co-pigmentation process. The total anthocyanin content was to 41% after storage in treatments without guar gum, but when using 1.25% guar gum the final concentration was 70% and there was a 2.4 fold increase in the half-life time of anthocyanins. A significant effect of guar gum addition on the antioxidant capacity of the samples was observed. In the second step, the anthocyanins were added together with 1.25% guar gum in the internal aqueous phase of the double emulsion and stored for 10 days at 40 °C in the presence of light. The double emulsion presented high encapsulation efficiency (90.6%) and high kinetic stability under the conditions evaluated, in addition to protecting anthocyanin molecules against degradation.