Mineral analysis of mono-floral New Zealand honey

The levels of 18 different minerals in ten locally produced mono-floral honeys (clover, honeydew, ka¯mahi, ma¯nuka, nodding thistle, ra¯ta¯ , rewarewa, ta¯wari, thyme and viper’s bugloss honey) were determined, as well as moisture content, pH, conductivity and colour. The most abundant minerals were potassium, phosphorus and calcium, ranging between 34.8–3640, 29.5–255 and 7.21–94.3 mg/kg, respectively. Potassium made up 73% of the total mineral content. There was a large range of mean total mineral contents, with honeydew honey having the highest level (4060 mg/kg) and viper’s bugloss honey the lowest (126 mg/kg). Honeydew had more than twice the mean total mineral contents than ka¯mahi, the next highest. The heavy metal contents (Cd, Pb and Zn) of the mono-floral honey types investigated were very low. A strong positive relationship between mean conductivity and total mineral content (r2 = 0.973), and pH and total mineral content (r2 = 0.776) was observed in this study

Response surface methodology optimization of vacuum-fried gold kiwifruit slices based on its moisture, oil and ascorbic acid contents

Response surface methodology was used to investigate the effects of a higher level of maltodextrin (MD) (40–70%) as a pretreatment for gold kiwifruit slices and the temperature and time used during vacuum frying of the samples on the moisture, oil and ascorbic acid contents of the products. The moisture content of vacuum-fried gold kiwifruit slices decreases with increases in frying temperature. The oil content of the sample increases with increases in frying temperature and time. The ascorbic acid content of the sample decreases with increases in frying temperature and MD level. When processing vacuum-fried gold kiwifruit slices, there is a need to use frying temperatures of 72.0–76.3C, frying times of 35.0–65.0 min and an MD level of 40% in order to achieve a product with moisture contents of 8.4–8.9% (dry basis) and acceptable qualities. The use of response surface methodology enabled the derivation of mathematical models for describing the effects of the independent variables on the dependent variables for vacuum-fried kiwifruit. Vacuum frying is one of the latest preservation method applied to fruits. This method processes the fruits at lower temperatures and reduced pressure, which enables the production of dried products with superior sensory and nutritional qualities. The information provided in this work will be very useful in producing vacuum-fried gold kiwifruit slices at optimal pretreatment and vacuum-frying conditions

Effect of cooking on the soluble and insoluble oxalate content of some New Zealand foods

Oxalates occur as end products of metabolism in a number of plant tissues; some leafy plants and some root crops contain markedly high levels of soluble and insoluble oxalates. When consumed these oxalates can bind calcium and other minerals. Measurement of oxalate content in vegetables commonly consumed in New Zealand shows that cooking reduces the oxalate content of the food by leaching losses into the cooking water. Roots and brassicas grown in New Zealand appear to contain relatively low levels of oxalates. Leafy vegetables such as silverbeet and NZ spinach appear to approach and exceed levels found in rhubarb stalks, although New Zealand silverbeet stems contain lower levels

Nutritional quality of almond, canarium, cashew and pistachio and their oil photooxidative stability

Hosseini Bai, S ORCiD: 0000-0001-8646-6423Daily consumption of nuts is recommended as a part of a healthy diet as they contain protein and are rich in beneficial fatty acids and essential nutrients. The nutritional qualities of nuts are affected by their fatty acid composition and other factors such as maturity. Oil oxidative stability is important to determine nut nutritional quality in terms of fatty acid composition over storage. Therefore, this study aimed to (a) assess the nutritional quality (photooxidative stability and nutrient composition) of almond, cashew, pistachio and canarium (a newly commercialised indigenous nut); and (b) explore differences in nutrient concentrations between immature and mature canarium nuts. A decrease in polyunsaturated fats after photooxidation in almond and pistachio was observed. Canarium oil did not change following photooxidation suggesting canarium may display a long shelf life when stored appropriately. Our study indicated that almond provided over 50% of the recommended daily intake for manganese whereas canarium intake provided 50% of the recommended daily intake for iron (for males). Pistachio was richer in potassium compared with other nuts and canarium was richer in boron, iron and zinc than other nut species. Mature canarium kernels were richer in boron, iron and zinc but contained less potassium than immature canarium. Therefore, the current study recommended to store kernels in dark to decrease oil photooxidation, and maturity of canarium kernels at the harvest time was important affecting nutrient concentrations of kernels. © 2018, Association of Food Scientists & Technologists (India)