Cassandra M. McDonough

Cooking Characteristics and Quality of Noodles from Food Sorghum

ABSTRACT Three white food sorghums, ATx631*RTx436, ATxARG*RTx436, and SC283-14, were decorticated, milled into flour and processed into 100% sorghum noodles. Flour, water, and salt (1%) were preheated using a hotplate or a microwave oven. The mixtures were put through a forming extruder to produce noodles. Extruded noodles were dried by three methods: air-dry method (23°C, 48 hr); one-stage (60°C, 30% rh, 3 hr), or two-stage (60°C, 100% rh for 2 hr followed by 60°C, 30% rh for 2 hr). Noodles were evaluated dry and after cooking. Sorghum flours with smaller particle sizes yielded better noodles. The microwave preheating method yielded better noodles than the hot-plate method. Stronger and firmer noodles, dry or cooked, were prepared using two-stage drying compared with the other drying methods. Fine flour that was preheated using a microwave oven and dried using the two-stage method gave the best noodles with moderate (10%) dry matter loss. Optimized processing conditions yielded sorghum noodles with good ...

Microscopy of pericarp development in the caryopsis of Sorghum bicolor (L.) Moench

Abstract Five sorghum varieties typifying differences in pericarp thickness were harvested at 0–34 days post anthesis, prepared and viewed by fluorescence, bright field, polarized light, and scanning electron microscopy. The development of the pericarp at various stages is described. The pericarp reached its maximum size around 21 days post anthesis. Compound starch granules were present in the ovary wall at anthesis and disappeared at 10–14 days post anthesis; only simple granules remained. The differences in pericarp thickness among the varieties are related to the quantity of starch in the mesocarp cells; the thick pericarp varieties contain more starch. All five varieties had maximum pericarp thickness at 5–7 days post anthesis, but values varied widely among grains. Few starch granules remained in the varieties with thin pericarps at maturity. These varieties carried the dominant Z gene. At maturity starch remained in varieties with thick pericarps; the recessive zz may have blocked resorption or stimulated extra production of the granules. A large range of pericarp thickness is possible when the z gene is recessive.

Effects of Sorghum (Sorghum bicolor (L.) Moench) Crude Extracts on Starch Digestibility, Estimated Glycemic Index (EGI), and Resistant Starch (RS) Contents of Porridges

Bran extracts (70% aqueous acetone) of specialty sorghum varieties (tannin, black, and black with tannin) were used to investigate the effects of sorghum phenolic compounds on starch digestibility, Estimated Glycemic Index (EGI), and Resistant Starch (RS) of porridges made with normal corn starch, enzyme resistant high amylose corn starch, and ground whole sorghum flours. Porridges were cooked with bran extracts in a Rapid Visco-analyser (RVA). The cooking trials indicated that bran extracts of phenolic-rich sorghum varieties significantly reduced EGI, and increased RS contents of porridges. Thus, there could be potential health benefits associated with the incorporation of phenolic-rich sorghum bran extracts into foods to slow starch digestion and increase RS content.

AIRBORNE STARCH GRANULES AS A POTENTIAL CONTAMINATION SOURCE AT ARCHAEOLOGICAL SITES

Abstract Well-known allergy literature attests to a presence of airborne starch granules from human and natural activities and illustrates that starch granules within pollen grains from starch-rich plants are released when pollen grains rupture in mid-air during thunderstorms. This study reports on starch granules extracted from Texas air samples and ruptured pollen grains from seven ethnographically important geophyte species, as well as maize (Zea mays L.). Starch granules from pollen grains are compared to those in storage organs of these plants. Results confirm that storage-like starch granules are airborne and that starch granules inside pollen can be indistinguishable from starch granules in the respective storage organs.

Functionality of rice and sorghum flours in baked tortilla and corn chips

ABSTRACT The effects of raw and gelatinized sorghum and rice flours on the structure and texture of baked corn and tortilla chips were evaluated. Dry masa flour was hydrated into masa, sheeted, and cut. Corn chips were baked in an air-impingement oven, and tortilla chips were baked first in a three-tier oven and then in an air-impingement oven. Baked tortilla chips required significantly greater force to break and were less susceptible to breakage during handling than baked corn chips. Raw and gelatinized, normal and waxy rice and sorghum flours significantly changed the texture and structure of baked chips. Waxy rice and sorghum flours reduced peak force and work, increased chip thickness, and improved overall acceptability (as assessed by a taste panel), but waxy rice and sorghum chips were more fragile and had a greater number of large central air cells. Waxy rice was more beneficial than waxy sorghum flour. Gelatinization of waxy flours increased thickness of baked chips, whereas gelatinization of non...

Effects of Brans from Specialty Sorghum Varieties on In Vitro Starch Digestibility of Soft and Hard Sorghum Endosperm Porridges

ABSTRACT Brans of specialty sorghum varieties (high tannin, black, and black with tannin) were used to investigate the effects of sorghum phenolic compounds on starch digestibility of soft and hard sorghum endosperm porridges. Endosperms of varieties with the highest and lowest grain hardness index were mixed with brans of specialty sorghum varieties in the ratio of 85:15 and cooked into porridges with distilled water using a Rapid Visco Analyzer. Brans of condensed tannin containing sorghum varieties (high-tannin and black with tannin sorghums) significantly (P < 0.05) decreased starch digestibility and estimated glycemic index (EGI) and increased resistant starch (RS) content of endosperm porridges. However, the addition of phenolic-rich tannin-free (mostly anthocyanins) black sorghum bran significantly (P < 0.05) increased starch digestibility and EGI but did not affect RS content of endosperm porridges. The disparate effects with black bran may, in part, result from its larger particle size and differ...

Structural Characteristics of Steam-Flaked Sorghum

ABSTRACT Sorghum undergoes structural changes during tempering, steam cooking, and flaking at various tempering moisture levels. Physical properties of flakes, digestibility, birefringence, scanning electron microscopy (SEM), and environmental SEM (ESEM) were used to evaluate the quality of steam-flaked sorghum from grain containing 11–23% water. As moisture levels increased, the flakes became stronger (57–69% whole flakes) and less dusty (9–4% fines). The diameter of the flakes varied among moisture levels, but preflake and final flake moisture contents increased as the temper level increased. Starch birefringence remained unchanged after tempering, and decreased only slightly after steam cooking; gelatinization occurred primarily during the flaking process. The steaming process prepared the grain for flaking by heating and softening the kernels. Tempering allowed extra water to penetrate inside the kernel endosperm. More starch granules had the opportunity to reach the glass transition temperature (T g)...

Effects of processing conditions and sorghum cultivar on alkaline-processed snacks

ABSTRACT Sorghum (Sorghum bicolor (L.) Moench) grain was boiled or autoclaved in alkali, washed, drained, and dried into shelf-stable half-products (pellets). The pellets were deep-fat fried to produce a crunchy snack product. Effects of cooking time, drying method (pellet moisture content), and sorghum cultivar on unfried and fried pellets were evaluated. Increasing the alkaline cooking time from 30 to 60 min decreased the yield of the pellets from 96 to 84% (on a dry weight basis). Cooked sorghum dried at room temperature (24°C) for 18 hr, followed by oven-drying at 50°C for an additional 18 hr, produced pellets with a low moisture content (≤5%), that required a higher frying temperature (≥220°C). However, cooked sorghum dried at room temperature for 18 hr followed by oven-drying at 50°C for 5 hr produced pellets with 9% moisture and a lighterdensity highly acceptable product when fried at 220°C. Fat content of fried pellets averaged 18%. The optimum method for producing a light, crunchy, fried product ...

Steam flaking characteristics of sorghum hybrids and lines with differing endosperm characteristics

ABSTRACT Commercial and food-type sorghum hybrids with differing kernel and endosperm characteristics were grown under comparable conditions and steam flaked in each of three years. The raw-grain kernel characteristics and proximate analyses were homogenous over the three-year period. The waxy hybrid produced large, translucent, durable flakes that had significantly higher enzyme-susceptible starch values for all years compared to the other varieties. Flakes with lower amylose contents (waxy endosperm) were positively correlated with percent whole flakes (r2 = 0.509), flake diameter (r2 = 0.846), and enzyme-susceptible starches (r2 = 0.564) and negatively correlated with higher flake fragility (r2 = -0.647), test weight (r2 = -0.626), and flake breakage (r2 = -0.560). The heterowaxy flakes had a good appearance and were generally comparable in quality to the nonwaxy commercial and experimental hybrids. Heterowaxy sorghum hybrids with good grain yields can provide improved quality grain and flakes without ...

Microstructure of wheat flour tortillas: effects of soluble and insoluble fibres / Microestructura de tortillas de harina de trigo: éfectos de la adición de fibra soluble e insoluble:

Soluble and insoluble fibres influenced both the quality and microstructure of dough and wheat flour tortillas. Doughs containing 8% soluble fibre had poor gluten development and extensive starch gelatinization during baking. This resulted in a tortilla with a dense, pasty crumb. Doughs containing 8% insoluble fibre had better gluten structures than those prepared using soluble fibres. Strands of insoluble fibre particles, however, physically disrupted the gluten network, causing the air bubbles to collapse, and decreased the shelf-stability of tortillas. It appears that soluble and insoluble fibres weaken the gluten matrix by different mechanisms.