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Rice parboiled at various combinations of soaking temperature and steaming time were analyzed by differential scanning calorimetry (DSC) and X‐ray diffraction (XRD). Generally, gelatinization enthalpy decreased as the soaking temperature increased from 30°C to 50°C and 70°C to 90°C, and gelatinization enthalpy decreased as steaming times increased from 4 and 8 min to 12 min. As expected, a distinctive A‐pattern was observed in the XRD of raw rice. The most severely parboiled laboratory sample (90°C for 12 min), showed no discernable change toward the V‐pattern. Crystallinity decreased from the raw rice (24.6%) with increased cooking temperature.

Rapid visco analysis (RVA) and differential scannning calorimetry (DSC) provided overall assessments of the effects of variable temperature soaking at 30, 50, 70, and 90°C and steaming at 4, 8, and 12 min. Calculation of the relative parboiling index (RPI) and percent gelatinization provided good metrics for determining the overall effects of partial parboiling. FT‐Raman and solid‐state 13C CP‐MAS NMR spectroscopies provided insight to conformational changes in protein and starch of paddy rice under various parboiling conditions. RVA showed lower pasting curves and DSC showed lower ΔH with increased temperature and steaming times. A large decrease in viscosity occurred with only the 30‐4 treatment as opposed to raw rice. This observation was consistent with FT‐Raman results that indicated substantial conversion of the protein from α‐helix to other conformations. DSC indicated incomplete gelatinization of starch, even with 90°C soaking and 12 min of steaming. Solid‐state 13C CP‐MAS NMR spectroscopy confirmed this result. However, it indicated the percent of Vh/amorphous plus the remaining crystalline starch in the 90‐12 treatment was equal to the amorphous and partially‐ordered starch in commercially parboiled rice. These results suggest that partial parboiling, 90°C soaking, and more than 8 min of steaming (ideally ≈12 min) of paddy rice is sufficient to induce changes that inactivate enzymes and provide enough starch gelatinization to prevent kernel breakage.

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Citation for this version held on GALA:Piletska, Elena, Karima, Kal, Coker, Raymond and Piletsky, Sergey (2010) Development of the custom polymeric materials specific for aflatoxin B1 and ochratoxin A for application with the ToxiQuant T1 sensor tool. London: Greenwich Academic Literature Archive. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Two polymers were computationally designed with affinity to two of the most 10 abundant mycotoxins aflatoxin B1 (AFB1) and ochratoxin A (OTA) for application in 11 the ToxiQuant T1 System. The principle of quantification of AFB1 and OTA using 12 the ToxiQuant T1 instrument comprised of a fluorimetric analysis of mycotoxins 13 adsorbed on the polymer upon exposure to UV light. High affinity of the developed 14 resins allowed the adsorption of both toxins as discrete bands on the top of the 15 cartridge with detection limit as low as 1 ng quantity of mycotoxins. 16

The control of the occurrence of mycotoxins in foods and feeds requires effective surveillance and quality control procedures which facilitate the identification and control of the mycotoxin problem respectively. Surveillance and quality control procedures involve a sequence of sampling, sample preparation, and analysis steps; and the integrity of the data produced by these procedures will be determined by the effectiveness of these steps. It is imperative that the sampling step is performed as accurately as possible so that the sample collected is representative of the batch of food or feed under investigation. Needless to say, the collection of a biased sample will completely invalidate the resultant analytical data. Most attempts to develop effective sampling protocols have focused upon the aflatoxins, since the majority of current regulations are concerned specifically with this group of mycotoxins. However, the design of effective sampling protocols has been severely hindered by the highly skewed distribution of the aflatoxins in foods and feeds. Studies already performed indicate that representative samples of commodities, composed of large particles (e.g., corn and oilseed kernels) should be 10 kg in weight, at least, and composed of approximately one hundred incremental samples. Similar studies have indicated that samples of oilseed cakes and meal, however, should be composed of fifty incremental samples which afford a composite sample of approximately 5 kg in weight.

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Peanut meal naturally contaminated with 3.5 mg/kg aflatoxin B1 (AFB1) was spiked with radiolabelled AFB1 (meal 14C-I0) and decontaminated by a small-scale copy of an industrial ammoniation process (meal 14C-I1). During the process 15% of the radioactivity was lost, whereas 90% of the remaining radiolabel could not be extracted from the meal. In the extractable part, AFB1 accounted for 10% of the radiolabel, consistent with a total AFB1 reduction of more than 99%. No degradation products were observed in the extracts. Four lactating cows were fed with a diet containing 15% of either meal 14C-I0 or 14C-I1 for 10 days. On day 9 of this treatment, respectively 23 and 67% of the radiolabel was excreted in the urine and faeces of cows fed meal 14C-I0, as compared with 2 and 101% in the case of cows fed meal 14C-I1. Milk contained respectively 1.35 (meal 14C-I0) and 0.25% (meal 14C-I1) of the radiolabel. Milk samples taken during the equilibrium stage contained respectively 5 and 0.5 ng/ml of AFB1-derived compounds. Aflatoxin M1 (AFM1) accounted for 50-80% of these compounds in the case of milk from cows fed 14C-I0, as compared with 6-20% in the case of 14C-I1. AFB1 to AFM1 carry-over rates for 14C-I0 or 14C-I1 were estimated to be respectively 0.5 and 5.9%. Only liver and kidney samples contained detectable levels of the radiolabel, being respectively 260 and 37 micrograms/kg for cows fed meal 14C-I0, and 10 and 3 micrograms/kg for those fed meal 14C-I1. In the latter case, more than 55% of the radiolabel in the liver could not be extracted, as compared with 90% in the group fed meal 14C-I1. A small part of the extractable radiolabel in the livers of cows fed meal 14C-I0 could be attributed to AFB1 and AFM1 (less than 1% of total radioactivity). In the case of the animals fed 14C-I1 there were indications for the presence of AFB1 and AFM1 (6% of total radioactivity). Decontamination of the highly contaminated (non-radiolabelled) peanut meal by two different industrial ammoniation processes, resulted in a similar reduction of the initial AFB1 levels of 3.5 mg/kg to 15 micrograms/kg. Feeding of diets containing 15% of the non-treated and two treated peanut meals to cows for a period of 10 days, resulted in AFM1 levels in milk of respectively 2.1, 0.04 and 0.07 ng/ml. AFB1 to AFM1 carry-over rates were calculated to be respectively 0.5, 2.0, and 3.6%. It is concluded that the efficient reduction of aflatoxin levels by ammoniation of contaminated peanut meal results in a strong reduction of aflatoxin-related residues in milk and meat of cows, most likely caused by a decreased bioavailability of the degradation products.