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Effects of food irradiation on allergen and nutritional composition of giant freshwater prawn are not well documented. Thus, this study aimed to investigate the effects of gamma irradiation on tropomyosin allergen, proximate composition, and mineral elements in Macrobrachium rosenbergii. In this study, prawn was peeled, cut into small pieces, vacuum packaged and gamma irradiated at 0, 5, 7, 10 and 15 kGy with a dose rate of 0.5 kGy/h using cobalt-60 as the source, subsequently determined the level of tropomyosin, proximate composition and mineral elements respectively. The results showed that band density of tropomyosin irradiated at 10 and 15 kGy is markedly decreased. Proximate analysis revealed that moisture, protein, and carbohydrate content were significantly different as compared with non-irradiated prawn. Meanwhile, gamma irradiated M. rosenbergii at 15 kGy was observed to be significantly higher in nickel and zinc than the non-irradiated prawn. The findings provide a new information that food irradiation may affect the tropomyosin allergen, proximate composition and mineral elements of the prawn.

Summary Synthesis of carboxymethyl starch (CMSS) from sago (Metroxylon sagu), an important agricultural commodity of Malaysia, was conducted in 30 L reactor vessel using isopropanol as the non-aqueous medium. CMSS of degree of substitution (DS) 0.24, 0.40, 0.54 and 0.80 was prepared by varying the molar ratio of sodium hydroxide and sodium monochloroacetate to anhydroglucose units including reaction time. Substitution of the hydroxyl groups on the native starch with carboxymethyl group was confirmed using Fourier transform infrared. All prepared samples were water-soluble at room temperature, producing high paste clarity. Carboxymethylation markedly reduced viscosity of CMSS compared to native sago. The particle size distribution also displayed increase in the granule size range compared to native sago. However X-ray diffractometry of CMSS revealed loss of crystallinity. Scanning electron microscopy showed that the granular smooth appearance of native starch was mostly distorted after carboxymethylation process at higher DS values. The synthesis of carboxymethyl sago starch with different degrees of substitution will add value to the sago industry as new functional biomaterial with potential application in the food and non-food industry.

Sago (Metroxylon sagu) starch was exposed to gamma-irradiation in air at doses 6, 10 and 25 kGy. Subsequent changes in the physicochemical and thermal properties were measured. The apparent amylose content and swelling power of irradiated sago starch was significantly reduced while reducing sugars and starch solubility were significantly increased due to degradation. X-ray diffraction studies showed that radiation did not affect the crystalline type but induced a decrease in the degree of crystallinity, indicating the destruction of the ordered distribution of neighboring polysaccharide chains in the starch granules, in particular of the amylopectin component, which is responsible for starch crystallinity. Differential scanning calorimetry (DSC) of irradiated sago starch showed a small but significant increase in the onset and peak transition temperatures at 10 and 25 kGy dose; the conclusion temperature and gelatinization enthalpy was not affected. SEM and particle size analysis produced no evidence of physical damage to sago starch up to 25 kGy dose radiation treatment since the granular appearance and size distribution was retained.

Edible bird’s nest (EBN) is widely consumed in South-East Asia as a health food product. In recent years, the adulteration of EBN is quite common due to its high economic value and limited supplies of the natural authentic product. Authentication and traceability of EBN demands time-consuming sequential analytical measurements to confirm that the product quality meets technical and regulatory requirements. Mid Infrared spectroscopy combined with chemometric analysis by Data-Driven Soft Independent Modelling of Class Analogy (DD-SIMCA) was used in this study to screen Malaysian EBNs for structural adulterants and for confirmation of geographical origin. The samples used were authentic processed EBNs of different grades (2A, 3A, 4A and 5A) from the swiftlet species Aerodramus fuciphagus supplied by Ministry of Health, Malaysia. Similarly, adulterants commonly used in EBN namely agar, Karaya gum, bovine gelatin, fish skin, melamine and porcine gelatine were also characterized. Adulterant mixtures were prepared gravimetrically at concentrations of 1, 5 and 10%w/w by combining appropriate quantities of adulterants with individual authentic EBN samples. Samples were then analyzed by Mid-Infrared – Attenuated Total Reflectance (MIR-ATR) spectroscopy. All test samples are properly categorized as members of the target class. However, 61% of the tested adulterated EBNs were correctly classified as ‘alien’ or non-authentic samples. The sensitivity and specifity values for DD-SIMCA models applied to origin determination ranged from 90 to 100% for production regions from Kelantan, Perak and Malacca. MIR-ATR spectroscopy in combination with DD-SIMCA modelling has shown potential as a rapid screening technique to detect the presence adulterants and confirm the provenance of EBN produced in Malaysia. Further work is required to validate the approach with a larger set of authentic samples and for a wider range of adulterants including flavour enhancers and preservatives.

The effect of gamma-irradiation on formation of resistant starch (RS) in corn starch with different amylose content was examined. Normal corn starch, waxy corn starch, and high amylose corn starch (Hylon V and Hylon VII) were irradiated at 5, 10, 25 and 50 kGy. Gamma-irradiation at 5 kGy increased the amylose-like molecules in starches and thus significantly enhanced the RS content (p0.05). Highest RS content was produced by 50 kGy irradiated in all the starch samples (p0.05). The irradiation-induced RS was more evident in waxy corn starch, followed by high amylose corn starch and normal corn starch.

Photo-stimulated luminescence (PSL) technique was applied to detect irradiated black pepper (Piper nigrum), cinnamon (Cinnamomum verum) and turmeric (Curcuma longa) after dark storage for 1 day, 3 and 6 months. Using screening and calibrated PSL, all samples were correctly discriminated between non-irradiated and spices irradiated with doses 1, 5 and 10 kGy. The PSL photon counts (PCs) of irradiated spices increased with increasing dose, with turmeric showing highest sensitivity index to irradiation compared to black pepper and cinnamon. The differences in response are possibly attributed to the varying quantity and quality of silicate minerals present in each spice sample. PSL signals of all irradiated samples reduced after 3 and 6 months storage. The results of this study provide a useful database on the applicability of PSL technique for the detection of Malaysian irradiated spices.