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BACKGROUND: Knowledge of the bioactive content of sweet sorghum syrups compared to other common food-grade syrups will expand their utilisation as a food source. Total phenolic content (TPC), phenolics evaluated by high-performance liquid chromatography, antioxidant 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging activities and oxygen radical absorbance capacity (ORAC), as well as colour of high-fructose corn syrup (HFCS), corn, honey, maple, agave, rice and grain sorghum syrups, were compared to 10 commercial sweet sorghum syrups. RESULTS: Sweet sorghum syrups contained markedly higher (P ≤ 0.05) TPC (6471 ± 1823 mg L-1 ) compared to the other syrups (596 ± 497 mg L-1 ). HFCS, corn, white grain sorghum and rice syrups had negligible and low DPPH radical scavenging activities and ORAC values, respectively. DPPH activities, ORAC and colour values of the sweet sorghum syrups were also markedly (P ≤ 0.05) higher than other syrups and highly related. The predominant phenolic components identified in sweet sorghum syrups were phenolic acids. Ellagic acid and protocatechuic acid were found in sorghum syrups ranging in concentration from 335-1177 and 53-485 µg g-1 , respectively. Sinapic acid was detected in several sorghum syrups, ranging in concentrations between 21 and 3654 µg g-1 . CONCLUSION: HFCS, corn, white grain sorghum and rice syrups demonstrated low bioactivity with negligible and low DPPH activities and ORAC values, respectively. The TPC, DPPH, ORAC and colour values of the sweet sorghum syrups were related to each other and markedly (P ≤ 0.05) higher compared to the other syrups. Phenolic acids were the predominant phenolic compounds identified in sorghum syrups and represent potential for health benefits. Published 2020. This article is a U.S. Government work and is in the public domain in the USA.

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The inhibitory activity of soluble and insoluble starch (0-550 ppm/Brix) in factory raw sugars were investigated using simulated refinery carbonatation clarification reactions to underpin what causes the undesirable formation of CaCO3 crystal fines (≤5 µm). It was found that CaCO3 crystal growth was inhibited mostly by soluble starch by forming starch-Ca2+ metal complexes. Insoluble (granular) starch, however, had a greater affinity for inhibiting CaCO3 crystallization because it retained the carbonatation clarification reactants, i.e., Ca2+and OH-, in the granule interior which caused granule gelatinization and increased viscosity of the melt liquor. Causes for poor press filterability and CaCO3 fines using raw sugar melts were found to be complex and attributed to the combinatorial roles that both soluble and insoluble starch have, among other impurities. More studies are now warranted at the carbonatation refinery to correlate processing characteristics with raw sugars quality attributes to underpin how each impurity impedes carbonatation.

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Recently, as previously for fat and protein, there has been negative discussion about carbohydrate, including blaming it for the rise of obesity and related metabolic conditions, even though overconsumption and sedentary lifestyles are more defined contributors. In many parts of the world, natural sugar (sucrose) from sugar cane is the main dietary source of carbohydrate. Considerable misinformation about sugar is in the public domain with the average consumer being unaware of (i) the critical need of body cells, particularly brain cells, for sugar to function, (ii) the multitude of functionalities other than sweetening that sugar imparts, and (iii) micronutrients delivered with many sugar products.

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Industrial starch methods in the sugar industry are affected by sugarcane- and processing-derived colourants, and it was presumed that these methods are mathematically equatable. Using the USDA Starch Research method as a reference and factory raw sugars, the impact of colourants on the accuracy, precision, limits of detection/quantification, and mathematical equatability of the starch methods were investigated. Approximately 26-55% of raw sugar colour contributed to starch-I3- absorbance. The exclusion of a colour blank negatively affected method accuracy and the addition of a colour blank confirmed that these methods measured mostly colour instead of starch. Inefficient starch solubilization and the inability to standardize sugar colourants explained why starch results from these methods could not be mathematically equated to the USDA Starch Research method, or among different methods. An industrial starch method that efficiently solubilizes starch and includes a colour blank is urgently needed.

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The sporadic appearance of floc from refined, white cane sugars in alcohol beverages remains a technical problem for both beverage manufacturers and sugar refiners. Cane invert sugars mixed with 60% pure alcohol and water increased light scattering by up to ∼1000-fold. Insoluble and soluble starch, fat, inorganic ash, oligosaccharides, Brix, and pH were not involved in the prevailing floc-formation mechanism. Strong polynomial correlations existed between the haze floc and indicator values (IVs) (color at 420 nm pH 9.0/color at pH 4.0-an indirect measure of polyphenolic and flavonoid colorants) (R2 = 0.815) and protein (R2 = 0.819) content of the invert sugars. Ethanol-induced denaturation of the protein exposed hydrophobic polyphenol-binding sites that were further exposed when heated to 80 °C. A tentative mechanism for floc formation was advanced by molecular probing with a haze (floc) active protein and polyphenol as well as polar, nonpolar, and ionic solvents.

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Several analytical starch methods exist in the international sugar industry to mitigate starch-related processing challenges and assess the quality of traded end-products. These methods use iodometric chemistry, mostly potato starch standards, and utilize similar solubilization strategies, but had not been comprehensively compared. In this study, industrial starch methods were compared to the USDA Starch Research method using simulated raw sugars. Type of starch standard, solubilization approach, iodometric reagents, and wavelength detection affected total starch determination in simulated raw sugars. Simulated sugars containing potato starch were more accurately detected by the industrial methods, whereas those containing corn starch, a better model for sugarcane starch, were only accurately measured by the USDA Starch Research method. Use of a potato starch standard curve over-estimated starch concentrations. Among the variables studied, starch standard, solubilization approach, and wavelength detection affected the sensitivity, accuracy/precision, and limited the detection/quantification of the current industry starch methods the most.

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In approximately 25% of the sugarcane-producing countries worldwide, conventional sugarcane (Saccharum spp. hybrids) is exposed to damaging freezes. A study was conducted during the 2009 and 2010 harvest seasons to compare late-season freeze tolerance among three groups: commercial Louisiana sugarcane genotypes, early generation genotypes selected for cold tolerance in the U.S. Department of Agriculture sugarcane breeding programs at Houma, LA, and Canal Point, FL, and potential energycane genotypes selected for high total biomass per acre. Mannitol concentrations in cane juice following freezing temperatures were determined to evaluate levels of cold tolerance. Genotypes selected for cold tolerance in Houma, LA, had significantly more late-season freeze tolerance than commercial sugarcane genotypes and genotypes selected in Canal Point, FL. Genotypes showing the most cold tolerance were Ho02-146 and Ho02-152, and those that were most highly susceptible were US87-1006 and US87-1003 (early-generation breeding genotypes) and L99-233 (commercial genotype). Broad-sense heritability for late-season cold tolerance in the two-year study was estimated at g(2) = 0.78. The enzymatic mannitol analysis successfully differentiated high-fiber energycane genotypes from those from other sources.

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A rapid research method using microwave-assisted probe ultrasonication was developed to quantify total, insoluble, and soluble starch in various sugar crop products. Several variables affecting starch solubilisation were evaluated, (1) heating method, (2) boiling time, (3) probe ultrasonication time, (4) water loss, (5) concentration, (6) sample colour, and (7) sample. The optimised method solubilises < 40,000 ppm insoluble starch with microwave-assisted sonication in 6 min, has acceptable precision (<6% CV), accuracy (⩾ 95%), uses a corn starch reference, and incorporates a colour blank to remove contribution from natural colourants found in industrial samples. This method was validated using factory samples and found applicable to sugarcane and sweet sorghum bagasse (3% CV), mixed juices (2%), massecuites (4%), molasses (7%), and raw sugars (12%), 100% satisfactory performance z-scores were also obtained. Total starch values obtained with this method were significantly higher than those measured using other methods presently accepted by the sugar industry.

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Sugar crops contain a broad variety of carbohydrates used for human consumption and the production of biofuels and bioproducts. Ion chromatography with integrated pulsed amperometric detection (IC-IPAD) can be used to simultaneously detect mono-, di-, and oligosaccharides, oligosaccharide isomers, mannitol, and ethanol in complex matrices from sugar crops. By utilizing a strong NaOH/NaOAc gradient method over 45 min, oligosaccharides of at least 2-12 dp can be detected. Fingerprint IC oligosaccharide profiles are extremely selective, sensitive, and reliable and can detect deterioration product metabolites from as low as 100 colony-forming units/mL lactic acid bacteria. The IC fingerprints can also be used to (i) monitor freeze deterioration, (ii) optimize harvesting methods and cut-to-crush times, (iii) differentiate between white refined sugar from sugar cane and from sugar beets, (iv) verify the activities of carbohydrate enzymes, (v) select yeasts for ethanol fermentations, and (vi) isolate and diagnose infections and processing problems in sugar factories.

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In sugarcane processing, starch is considered an impurity that negatively affects processing and reduces the quality of the sugar end-product. In the last decade, there has been a general world-wide increase in starch concentrations in sugarcane. Industrial α-amylases have been used for many years to mitigate issues arising from starch in the sugarcane industry. Mixed results have prompted further studies of the behaviour of different physical forms of starch and their interactions with α-amylases during processing. By using corn starch as a reference in model juices and syrups, processing parameters, activities, and hydrolysis of insoluble, swollen, and soluble starch forms were evaluated for two commercial α-amylases with high (HT) and intermediate (IT) temperature stability, respectively. The ability of starch to solubilise across a sugarcane factory is largely limited by increased Brix values. Optimum target locations and conditions for the application of α-amylases in sugarcane processing are discussed in detail.

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Bacterial contamination during industrial yeast fermentation has serious economic consequences for fuel ethanol producers. In addition to deviating carbon away from ethanol formation, bacterial cells and their metabolites often have a detrimental effect on yeast fermentative performance. The bacterial contaminants are commonly lactic acid bacteria (LAB), comprising both homo- and heterofermentative strains. We have studied the effects of these two different types of bacteria upon yeast fermentative performance, particularly in connection with sugarcane-based fuel ethanol fermentation process. Homofermentative Lactobacillus plantarum was found to be more detrimental to an industrial yeast strain (Saccharomyces cerevisiae CAT-1), when compared with heterofermentative Lactobacillus fermentum, in terms of reduced yeast viability and ethanol formation, presumably due to the higher titres of lactic acid in the growth medium. These effects were only noticed when bacteria and yeast were inoculated in equal cell numbers. However, when simulating industrial fuel ethanol conditions, as conducted in Brazil where high yeast cell densities and short fermentation time prevail, the heterofermentative strain was more deleterious than the homofermentative type, causing lower ethanol yield and out competing yeast cells during cell recycle. Yeast overproduction of glycerol was noticed only in the presence of the heterofermentative bacterium. Since the heterofermentative bacterium was shown to be more deleterious to yeast cells than the homofermentative strain, we believe our findings could stimulate the search for more strain-specific antimicrobial agents to treat bacterial contaminations during industrial ethanol fermentation.

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A new plant source, sugarcane, was used to produce the stilbenes piceatannol and resveratrol. Both stilbenes were identified in sugarcane billet stalks (12 mm) after incubation at room temperature for 3 days. Low concentrations of piceatannol (30.6 µg/g) and resveratrol (12.3 µg/g) were detected at day 3. At day 7 of incubation higher concentrations of piceatannol (1659 µg/g) and resveratrol (73 µg/g) were produced. Sugarcane juice obtained from billets that were incubated for 7 days contained high levels of piceatannol (8.5 mg/L) and resveratrol (1.2 mg/L). Although high stilbene concentrations were determined in the sugarcane variety L 97-128, two other varieties (Ho 95-988 and LCP 85-384) displayed lower stilbene concentrations after incubation for 7 days. The total phenolic content (TPC) and antioxidant activities of incubated sugarcane extracts were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and ferric reducing antioxidant power (FRAP). The TPC and antioxidant activities were highest in sugarcane extracts that were incubated for 7 days. This study details a postharvest method to produce stilbene-enriched sugarcane with increased levels of piceatannol and resveratrol.

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Mannitol is a major deterioration product of Leuconstoc mesenteroides bacterial metabolism of sucrose and fructose from both sugarcane and sugar beet. The effect of crystallization conditions on the mannitol partition coefficient (K(eff)) between impure sucrose syrup and crystal has been investigated in a batch laboratory crystallizer and a batch pilot plant-scale vacuum pan. Laboratory crystallization was operated at 65.5°C (150°F), 60.0°C (140°F), and 51.7°C (125°F) with a 78.0 Brix (% refractometric dissolved solids) pure sucrose syrup containing 0%, 0.1%, 0.2%, 1.0%, 2.0%, 3.0%, and 10% (at 65.5°C only) mannitol on a Brix basis. Produced mother liquor and crystals were separated by centrifugation and their mannitol contents measured by ion chromatography with integrated pulsed amperometric detection (IC-IPAD). The extent of mannitol partitioning into the crystals depended strongly on the mannitol concentration in the feed syrup and, to a lesser extent, the crystallization temperature. At 65.5 and 60.0°C, the K(eff) varied from ~0.4% to 3.0% with 0.2% to 3.0% mannitol in the feed syrup, respectively. The mannitol K(eff) was lower than that reported for dextran (~9-10% K(eff)), another product of Leuconstoc deterioration, under similar sucrose crystal growth conditions. At 10% mannitol concentration in the syrup at 65.5°C, co-crystallization of mannitol with sucrose occurred and the crystal growth rate was greatly impeded. In both laboratory and pilot plant crystallizations (95.7% purity; 78.0 Brix; 65.5°C), mannitol tended to cause conglomerates to form, which became progressively worse with increased mannitol syrup concentration. At the 3% mannitol concentration, crystallization at both the laboratory and pilot plant scales was more difficult. Mannitol incorporation into the sucrose crystal results mostly from liquid syrup inclusions but adsorption onto the crystal surface may play a minor role at lower mannitol concentrations.

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The effect of the U.S. and worldwide change from burnt to unburnt (green) sugar cane harvesting on processing and the use of sugar cane leaves and tops as a biomass source has not been fully characterized. Sugar cane whole-stalks were harvested from the first ratoon (repeat) crop of five commercial, Louisiana sugar cane varieties (LCP 85-384, HoCP 96-540, L 97-128, L 99-226, and L 99-233). Replicated sample tissues of brown, dry leaves (BL), green leaves (GL), growing point region (GPR), and stalk (S) were separated. Composite juice from each tissue type was clarified following a hot lime clarification process operated by most U.S. factories. Only GPR and GL juices foamed on heating and followed the normal settling behavior of factory sugar cane juice, although GL was markedly slower than GPR. GPR juice aided settling. S juice tended to thin out rather than follow normal settling and exhibited the most unwanted upward motion of flocs. Most varietal variation in settling, mud, and clarified juice (CJ) characteristics occurred for GL. The quality rather than the quantity of impurities in the different tissues mostly affected the volume of mud produced: After 30 min of settling, mud volume per unit tissue juice degrees Brix (% dissolved solids) varied markedly among the tissues (S 1.09, BL 11.3, GPR 3.0, and GL 3.1 mL/degrees Brix). Heat transfer properties of tissue juices and CJs are described. Clarification was unable to remove all BL cellulosic particles. GL and BL increased color, turbidity, and suspended particles in CJs with BL worse than GL. This will make the future attainment of very high pol (VHP) raw sugar in the U.S. more difficult. Although optimization of factory unit processes will alleviate extra trash problems, economical strategies to reduce the amount of green and brown leaves processed need to be identified and implemented.

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In the United States, high-fructose corn syrup (HFCS) has become a sucrose replacement for honey bees and has widespread use as a sweetener in many processed foods and beverages for human consumption. It is utilized by commercial beekeepers as a food for honey bees for several reasons: to promote brood production, after bees have been moved for commercial pollination, and when field-gathered nectar sources are scarce. Hydroxymethylfurfural (HMF) is a heat-formed contaminant and is the most noted toxin to honey bees. Currently, there are no rapid field tests that would alert beekeepers of dangerous levels of HMF in HFCS or honey. In this study, the initial levels and the rates of formation of HMF at four temperatures were evaluated in U.S.-available HFCS samples. Different HFCS brands were analyzed and compared for acidity and metal ions by inductively coupled plasma mass spectroscopy. Levels of HMF in eight HFCS products were evaluated over 35 days, and the data were fit to polynomial and exponential equations, with excellent correlations. The data can be used by beekeepers to predict HMF formation on storage. Caged bee studies were conducted to evaluate the HMF dose-response effect on bee mortality. Finally, commercial bases such as lime, potash, and caustic soda were added to neutralize hydronium ion in HMF samples, and the rates of HMF formation were compared at 45 degrees C.

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The delivery of consignments of deteriorated sugarcane to factories can detrimentally affect multiple process units, and even lead to a factory shut-down. An enzymatic factory method was used to measure mannitol, a major degradation product of sugarcane Leuconostoc deterioration in the US, in press (consignment) and crusher juices collected across the 2004 processing season at a Louisiana factory. Weather conditions varied markedly across the season causing periods of the delivery of deteriorated sugarcane to the factory. A strong polynomial relationship existed between mannitol and haze dextran (R(2)=0.912) in press and crusher juices. Mannitol concentrations were usually higher than haze and monoclonal antibody dextran concentrations, which indicates: (i) the usefulness and higher sensitivity of mannitol to better predict sugarcane deterioration from Leuconostoc and other bacteria than dextran, and (ii) the underestimation by sugar industry personnel of the relatively large amounts of mannitol present in deteriorated sugarcane that can affect processing. Greater than ∼2500ppm/%Brix mannitol in juice predicts downstream processing problems. The enzymatic method is quantitative and could be used in a sugarcane payment formula. Approximately >300ppm/%Brix haze dextran in raw sugar indicated that the majority of the crystals were elongated. Approximately >600ppm/%Brix antibody dextran indicated when elongated crystals were predominant in the raw sugar. The enzymatic mannitol method underestimates mannitol in raw sugars.

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Factory staff must consider all costs to make sound economic decisions on how to improve the performance of evaporators, which includes knowing optimum pH levels to minimize sucrose losses. A factory study was conducted to determine the effects of target final evaporator syrup (FES) pH values across the season on sucrose losses. The factory operated Robert's type calandria evaporators, with two (2787 and 2322 m2) preevaporators in parallel and three sets of triple-body evaporators (1148 m2 each) in parallel; Rt values were 11.4 and 9.5 min in the two preevaporators, respectively, and increased from 10.0 to 21.8 min across the triple bodies. Gas chromatography was used to determine sucrose losses as Delta%glucose/%sucrose ratios on a degrees Brix basis. Most sucrose losses to acid hydrolysis occurred in the preevaporators. Increasing the target pH of the FES or clarified juice (CJ) systematically reduced losses of sucrose; however, scaling effects overrode pH effects in later bodies. Seasonal effects on evaporator sucrose losses were dramatic. In the early season when cane quality was lowest, higher amounts of impurities catalyzed further hydrolysis of sucrose. In the late season, resilient scale built-up across the season contributed to higher hydrolysis. An optimum target FES pH of approximately 6.3-6.5 measured at room temperature (equivalent to a CJ pH of approximately 7.1-7.3) is recommended, with a higher target FES pH in the early season or when processing immature cane, to reduce excessive losses. Across the evaporation station, the juice/syrup pH decreased up to the 2nd body with a consistent increase in the 3rd body due to evaporation of volatile acids into the condensate. Equations to assess the economic implications of evaporator sucrose losses are described. A target FES pH of 5.9 caused a season average sucrose loss of 0.55% equivalent to 1.52 lbs sucrose lost/ton of cane and a minimum USD 390,400 loss in profits. In contrast, a target FES pH of 6.5 reduced this sucrose loss to 0.36% and 1.01 lbs sucrose lost/ton of cane and saved the factory a minimum of USD 131,100.

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In the U.S., cold lime clarification remains the clarification process of choice in raw sugar manufacturing. A comparative study of cold vs intermediate lime clarification was undertaken at a factory that operated intermediate liming (approximately 30% mixed juice (MJ) of pH 5.2 +/- 0.3 was preheated to 87-93 degrees C to help maintain clean limed juice heaters, incubated at approximately 54 degrees C, and then limed) but still had the pipes to revert to cold liming (MJ incubated and limed at approximately 40 degrees C) for this study. Hourly samples were collected over a 6 h sampling period across cold and intermediate clarification processes on two consecutive days, respectively, and this was repeated three times across the 1999 grinding season. A total of 1.57% less sucrose was lost to inversion reactions across intermediate rather than cold liming. In intermediate liming, which required approximately 4.6% less lime, preheating of only 30% of the MJ markedly removed color (-29%), dextran (-10%), and starch (-24%) and caused large flocs to form that settled faster in the clarifiers. Faster settling led to an impressive 4.6% (season average) more turbidity removal across the clarifiers in intermediate rather than cold liming. Intermediate clarified juice (CJ) turbidity (season average 2028 ICU +/- 675) was approximately half of cold CJ turbidity (average 3952 ICU +/- 1450) with over 2-fold more CJ turbidity control. Subsequent turbidity values and control were significantly improved in the final evaporator syrup samples too. For both processes, juice incubation caused approximately 10% color removal, but this was offset by color formation on liming, because of the alkaline degradation of invert; however, overall, more color was removed than formed in intermediate liming. Starch was reduced in the incubator tank, for both processes, because added filtrate reduced the acidity enabling natural diastase from the cane to degrade starch. Some dextran occasionally formed in the incubator tank, in both processes. Summed across measured parameters, intermediate liming appears to offer several advantages over cold liming.

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