Dropping macadamia nuts‐in‐shell reduces kernel roasting quality

BACKGROUND: Macadamia nuts (‘nuts‐in‐shell’) are subjected to many impacts from dropping during postharvest handling, resulting in damage to the raw kernel. The effect of dropping on roasted kernel quality is unknown. Macadamia nuts‐in‐shell were dropped in various combinations of moisture content, number of drops and receiving surface in three experiments. After dropping, samples from each treatment and undropped controls were dry oven‐roasted for 20 min at 130 °C, and kernels were assessed for colour, mottled colour and surface damage. RESULTS: Dropping nuts‐in‐shell onto a bed of nuts‐in‐shell at 3% moisture content or 20% moisture content increased the percentage of dark roasted kernels. Kernels from nuts dropped first at 20%, then 10% moisture content, onto a metal plate had increased mottled colour. Dropping nuts‐in‐shell at 3% moisture content onto nuts‐in‐shell significantly increased surface damage. Similarly, surface damage increased for kernels dropped onto a metal plate at 20%, then at 10% moisture content. CONCLUSION: Postharvest dropping of macadamia nuts‐in‐shell causes concealed cellular damage to kernels, the effects not evident until roasting. This damage provides the reagents needed for non‐enzymatic browning reactions. Improvements in handling, such as reducing the number of drops and improving handling equipment, will reduce cellular damage and after‐roast darkening. Copyright © 2010 Society of Chemical Industry     

Effects of oil roasting temperature and time on the quality of two Macadamia integrifolia cultivars

The effects of oil roasting temperature and time on the quality of kernels from two Macadamia integrifolia cultivars, were determined. A high quality product was obtained by roasting at 115°C for 19–35 min, 125°C for 10–14 min or 135°C for 4 min. There was a significant deterioration in the quality of nuts from all roasting treatments when stored for 6 months at ambient temperature in lacquered cans at a pressure of ?85 kPa. Further deterioration had occurred after 12 months storage.     

Degradation kinetics of tomato juice quality parameters by ozonation

Tomato juice samples were ozonated with control variables of ozone concentration (1.6–7.8 %w/w) and treatment time (0–10 min). Effects of ozone processing variables on quality parameters of pH, ^oBrix, titratable acidity (TA), cloud value, non-enzymatic browning, colour values ( L *, a *, and b *) and ascorbic acid (AA) content were determined. No significant changes ( P  > 0.05) in pH, ^oBrix, TA, cloud value and Non enzymatic browning (NEB) ( P  ≤ 0.05) were found with ozonation. L *, a * and b * colour values were significantly affected by ozone concentration and treatment time. A significant reduction of AA (96 %) was observed at an ozone concentration of 7.8%w/w and a treatment time of 10 min. Results presented in this study indicate that visual colour and nutritional quality is significantly affected during ozone processing. Thus, the effects of ozonation on the nutritional properties of tomato juice should be considered by processors prior to its adoption as a preservation technique.     

Investigation of the roasting conditions with minimal acrylamide generation in tropical almond (Terminalia catappa) nuts by response surface methodology

Considering the importance of acrylamide in heated foods, a study was conducted to find optimum conditions for roasting that will produce minimal acrylamide concentration in tropical almond nuts. The data obtained were analysed using response surface methodology. The results revealed that the most significant (P < 0.05) roasting conditions that affect the acrylamide concentration were the main effect of roasting temperature and the quadratic effects of the independent variables. The minimum acrylamide value (Y₁ = 41.848 μg/kg) was achieved at a roasting temperature of 150 °C, roasting time of 14.19 min and a loading capacity of 20.20 g/m² respectively.     

Changes in color parameters of corn kernels during roasting

Changes in color parameters (L*, a*, b*, ΔE*, h°, and C* values) of corn during roasting were investigated and subsequently described using mathematical models. Corn kernels were roasted for 50 min at 160, 180, 200, 220, and 240°C. The L*, b*, h°, and C* values tended to decrease more rapidly as the roasting temperature and time increased up to 220°C and 50 min, whereas a* and ΔE* values tended to increase. Variation of L* and ΔE* values was found to be proportional to the roasting temperature and time. Variation of L* value during roasting above 180°C was adequately described by a first-order model. Cubic model satisfactorily described changes in all of color parameters over the temperature range. Activation energies of L* and ΔE* values were determined as 34.04 and 79.16 kJ/mol, respectively. Results suggest that L* and ΔE* values may be used as color control indicators during roasting of corn kernels.     

Effect of gamma irradiation on the physico‐chemical and sensory properties of raw shelled peanuts (Arachis hypogaea L.) and pistachio nuts (Pistacia vera L.)

Backround The present study evaluated the quality of raw peanuts and pistachio nuts as a function of irradiation dose in order to determine dose levels causing minimal undesirable changes to these products. Physico‐chemical (colour, peroxide value, hexanal content, fatty acid composition, volatile compounds) and sensory (colour, texture, odour, taste) properties of raw peanuts and pistachio nuts were determined after irradiation at doses up to 7 kGy. Results Results showed an eight‐ and seven‐fold increase in peroxide value and a twelve and five‐fold increase in hexanal content after irradiation at a dose of 7 kGy for peanuts and pistachio nuts, respectively. An increase was also observed in saturated fatty acids (20.51–28.28% and 15.24–24.87%) with a parallel decrease in unsaturated fatty acids (79.49–71.72% and 84.76–75.13%) for peanuts and pistachio nuts, respectively. Likewise, volatile compounds such as aldehydes, alkanes, ketones and alcohols comprising secondary oxidation products of peanut and pistachio nut lipids increased after irradiation. Pistachio nut colour parameter a* and to a lesser extent parameters, L* and b* decreased after irradiation leading to a slight but noticeable darkening in product colour while colour parameter L*, b* and a* of raw peanut remained unchanged by irradiation up to 7 kGy. Conclusion Based on sensory evaluation, peanuts and pistachio nuts become unacceptable for consumption when irradiated at doses higher than 3 kGy. Copyright © 2009 Society of Chemical Industry     

Optimization of the roasting of robusta coffee (C. canephora conillon) using acceptability tests and RSM

With the objective of optimizing the roasting of robusta coffee (Coffea canephora Conillon), a two factor central composite design (11 samples) was used to optimise the settings for roasting time and the initial internal temperature of the roaster drum on response variables of acceptance with 25 consuming assessors, for the sensory attributes of beverage aroma, flavour and colour. Predictive models were also obtained for the instumental measurement of the colour of the beans and ground coffee. The optimum range for roasting was shown to be a time of 22–28 min at a temperature of 225–230°C, corresponding to the degree of roasting characterized by the following range of colour of roasted robusta beans: L* between 37.05 and 40.69, a* between 2.29 and 4.15 and b* between 2.70 and 6.29.     

Effect of Moisture Content,Nut Size and Hot-Oil Roasting Time on the Whole Kernel “Out-Turn” of Cashew Nuts (Anacardium occidentale) During Shelling

The effect of moisture content (MC), nut size and roasting time (RT) on the whole kernel out-turn (WKO) of cashew nuts during shelling was investigated in this study. Cashew nuts were graded into three sizes: small (18 – 22 mm), medium (23 – 25 mm) and large nuts (26 – 35 mm). About 3 kg of nuts from each grade was conditioned with water at 25°C to five moisture levels of 8.34, 11.80, 12.57, 15.40 and 16.84% (wb). The nuts were subjected to roasting in hot cashew nut shell liquid at a temperature range between 180 and 190°C for 0.75, 1.00, 1.25, and 1.50 min. The nuts were then shelled using a hand-operated shelling machine. The results showed that pre-shelling treatment of cashew nuts enhanced WKO. The single effect of MC, roasting time (RT) or nut size distribution is not enough for estimating WKO; it is rather by an interaction of these parameters. The average WKO of raw nuts was characteristically below 50% at all combinations of MC and RT. Pre-treatment by roasting was found to improve WKO considerably. The highest values were 96.96, 99.63 and 100% for large, medium and small-sized nuts at MC*RT of 16.84%*1 min, 16.84%*1 min and 15.4%*1.5 min respectively. As RT and MC increased, WKO increased within the experimental range.     

Optimal salting of macadamia (Macadamia integrifolia) nuts

Roasted macadamia (Macadamia integrifolia Storey) nuts were salted at various levels up to 19 g kg^?1 and presented to a taste panel. The results showed that the assessors could be divided into 'salt dislikers', to whom perceived quality decreased linearly with increase in salt content, and 'salt likers', to whom perceived quality increased as the salt content increased. It follows that the nuts can be produced to suit these two market segments separately, or else a single lightly salted compromise product can be offered to both groups.     

Changes in volatile compounds and sensory quality during toasting of Spanish almonds

Toasting is one of the most important unit operations in turrón manufacture. The main objective was to study changes in volatile compounds and sensory odour and aroma during almond toasting. Two almond cultivars were studied 'Comuna' and 'Marcona'. CIE L * a * b * colour, instrumental aroma and sensory odour and flavour were evaluated in toasted almonds (200 °C: the most popular temperature for almond toasting in convection ovens) at five times from 12 to 23 min. The main pyrazines found were: 2,5-dimethylpyrazine, 2-ethyl-3-methylpyrazine, 2-methylpyrazine and 2,4-dimethyl-3-ethylpyrazine. Pyrazines, furans and pyrroles concentrations in 'Comuna' almonds were higher than in 'Marcona' samples at the end of toasting; however, sensory analysis showed that 23 min were too long for 'Comuna' almonds (burnt notes) and shorter toasting time must be applied. Based on both instrumental and sensory colour and aroma data, the recommended toasting time at 200 °C in convection ovens for 'Comuna' and 'Marcona' almonds should be 20 min.     

坚果的主要生物活性成分及其保健作用

坚果作为高档零食,其营养价值和保健功能也越来越受到人们的关注?本论文综述了常见坚果(如澳洲坚果、核桃、榛子、杏仁、松子、板栗、山核桃、开心果,日本核桃、巴西坚果、花生等)中的酚类(原花青素、酚酸、黄酮、单宁、烷基酚、维生素E等)?酸类?甾醇类、色素(类胡萝卜素、叶绿素等)、硒、糖苷、功能性脂肪酸等营养物质和生物活性成分,并阐述了食用坚果与预防心血管疾病?延年益寿?预防糖尿病?控制体重等保健作用的关系?这对于进一步研究坚果与健康的关系、正确挑选与消费坚果均具有较好的指导意义。     

Effect of hot water treatment of in-shell pecans on physicochemical properties and consumer acceptability of roasted pecan kernels

The effect of hot water pre-treatment of in-shell pecans on physicochemical properties, consumer acceptance and purchase intent of dehulled and roasted kernels was evaluated. In-shell pecans were first subjected to hot water at 70, 80 and 90 °C for 8.6, 6.6 and 4.6 min respectively and kernels were later dry roasted at 160 °C for 10 min. The physicochemical properties of hot water treated and untreated nuts, before and after roasting were determined. Furthermore, consumer acceptance and purchase intent of the roasted kernels were determined. Hot water treatment, alone and subsequent roasting had minimal effect on pecans’ physicochemical properties. Consumers liked (P < 0.05) the colour and aroma of treated pecans. No effect (P > 0.05) of pre-treatment was observed on the acceptability of other sensory attributes. Safety claim increased treated pecans’ overall liking; however, it decreased purchase intent. Hot water treatment showed promise as a post-harvest microbial intervention strategy without affecting the physicochemical properties and consumer acceptability.     

Quality changes in macadamia kernel between harvest and farm-gate

BACKGROUND: Macadamia integrifolia, Macadamia tetraphylla and their hybrids are cultivated for their edible kernels. After harvest, nuts‐in‐shell are partially dried on‐farm and sorted to eliminate poor‐quality kernels before consignment to a processor. During these operations, kernel quality may be lost. In this study, macadamia nuts‐in‐shell were sampled at five points of an on‐farm postharvest handling chain from dehusking to the final storage silo to assess quality loss prior to consignment. Shoulder damage, weight of pieces and unsound kernel were assessed for raw kernels, and colour, mottled colour and surface damage for roasted kernels. RESULTS: Shoulder damage, weight of pieces and unsound kernel for raw kernels increased significantly between the dehusker and the final silo. Roasted kernels displayed a significant increase in dark colour, mottled colour and surface damage during on‐farm handling. CONCLUSION: Significant loss of macadamia kernel quality occurred on a commercial farm during sorting and storage of nuts‐in‐shell before nuts were consigned to a processor. Nuts‐in‐shell should be dried as quickly as possible and on‐farm handling minimised to maintain optimum kernel quality. Copyright © 2010 Society of Chemical Industry     

Evaluation of CIE-lab colour parameters during the clarification of a sugar syrup from Mesquite pods (Prosopis Pallida L.)

Summary There are several commercial sugar syrups obtained from the Mesquite pods, however their dark-brown colour limits their use in the food industry. In this work we clarified sugar syrups from Mesquite pods by a two-step procedure: (1) lime-milk treatment with the addition of different amounts of calcium hydroxide and aluminium sulphate, and (2) ion-exchange treatment using A-400 anionic and/or C-100 cationic resins. Samples were evaluated for colour using the Hunter Lab colorimeter (Hunter Associates Laboratory Inc, Reston, VA, USA) (L*, a*, b*, ) and for sensory acceptability during the clarification process. The results showed that with the addition of 7.5% calcium hydroxide and 8.0% aluminium sulphate, followed by treatment with the anionic resin A-400, a syrup with a high degree of purity (92.3%) and a lighter-brown colour than other commercial samples could be obtained. The colour values, as measured by the Hunter meter were; a lightness of L* = 6.17 and a yellow colour of 0.74 expressed as a a/b* ratio. A negative correlation was obtained between the total polyphenol content (TP) in the sugar extract and the lightness values (L*); L* = 15.50–0.00511 TP (mg kg^–1). The A-400 resin retained the greatest amount of polyphenols (92.9%). CIE-Lab parameters are proposed as a good means for objective colour comparison with other studies on the clarification of sugar syrups.     

Quality Evaluation of Shelled and Unshelled Macadamia Nuts by Means of Near‐Infrared Spectroscopy (NIR)

The quality of shelled and unshelled macadamia nuts was assessed by means of Fourier transformed near‐infrared (FT‐NIR) spectroscopy. Shelled macadamia nuts were sorted as sound nuts; nuts infected by Ecdytolopha aurantiana and Leucopteara coffeella; and cracked nuts caused by germination. Unshelled nuts were sorted as intact nuts (<10% half nuts, 2014); half nuts (March, 2013; November, 2013); and crushed nuts (2014). Peroxide value (PV) and acidity index (AI) were determined according to AOAC. PCA‐LDA shelled macadamia nuts classification resulted in 93.2% accurate classification. PLS PV prediction model resulted in a square error of prediction (SEP) of 3.45 meq/kg, and a prediction coefficient determination value (R_p²) of 0.72. The AI PLS prediction model was better (SEP = 0.14%, R_p² = 0.80). Although adequate classification was possible (93.2%), shelled nuts must not contain live insects, therefore the classification accuracy was not satisfactory. FT‐NIR spectroscopy can be successfully used to predict PV and AI in unshelled macadamia nuts, though.     

Fracture Resistance of Cashew Nuts as Influenced by Pre-Shelling Treatment

The fracture resistance of raw and pre-treated cashew nuts during uni-axial compressive loading was investigated. Cashew nut samples were subjected to two pre-shelling treatments, namely: steam boiling and roasting in hot cashew nut shell liquid. Two loading rates of 2.5 and 50 mm/min and two loading orientations (longitudinal and transverse) were considered for fracture resistance of pre-treated cashew nuts using a 50 kN capacity Instron testing machine. The data obtained were subjected to analysis of variance. The average values at 2.5 mm/min were 342 and 318 N for raw nuts, 321 and 242 N for roasted nuts, and 341 and 309 N for steam boiled nuts during longitudinal and transverse loading, respectively; whereas corresponding values at 50 mm/min were 784 and 763 N for raw nuts, 517 and 464 N for roasted nuts, and 436 and 398 N for steam boiled nuts, respectively. In each of the pre-treatment methods and loading rates, more force was required to crack cashew nuts during longitudinal loading than transverse loading; and for each loading rate, pre-treated nuts generally required less force than raw nuts.     

Effect of polyphenol and pH on cocoa Maillard-related flavour precursors in a lipidic model system

Polyphenol and pH influence the flavour quality of cocoa beans during roasting. Amino acids and reducing sugars are flavour precursors in cocoa beans, which develop into cocoa-specific aroma through Maillard reactions during roasting. A central composite design was applied to determine the combined effect of polyphenol and pH on the flavour precursors during cocoa roasting at 120 °C for 45 min using a lipidic model system. Polyphenol was added at 40, 80 and 120 g kg⁻¹ and pH was adjusted to 4.5, 6 and 7.5. The response surface methodology revealed that a lower concentration of amino acids and reducing sugars was obtained at higher polyphenol concentration (120 g kg⁻¹) and lower pH value (4.5). Based on the constraints set, the best polyphenol concentration of 43–58 g kg⁻¹ and pH of 7.0–7.5 was found to be optimum for the formation of flavour precursors in this lipidic model study.     

Effect of temperature and fruit-moisture content on discolouration of dried, sulphured Bon Chretien pears during storage

Summary Discolouration of Bon Chretien pears which had been treated with sulphur dioxide and which had moisture contents of either 16, 18 or 20%, was monitored during storage at 4, 7, 10 and 20 °C. Colour was quantified in terms of CIE L*, a*, b*, hue and chroma. L* was used to predict quality retention. Discolouration was categorized as a decrease in all colour parameters, except a* which increased with storage. Measurement of L* showed that only fruit at 16% moisture content and stored at T ≤ 10 °C retained their original colour. The rate of change in overall colour was observed in the following order at 20 °C, 20% > 18 > 16% moisture content. Fruit with 18 and 20% moisture content could be stored at 10 °C for at least 140 weeks without changing their quality grading. Storage at 20 °C shortened this period to 60 and 27 weeks for fruit at 18 and 20% moisture content, respectively.     

Active edible coatings with Boldo extract added and their application on nut products: reducing the oxidative rancidity rate

Brazil and Cashew nuts were coated with pure (gelatin, chitosan, sodium caseinate) or blended (gelatin:chitosan, gelatin:sodium caseinate) coating solutions, with and without Boldo‐of‐Chile extract. Brazil nuts exhibited lower moisture content (1.6%) and higher fat content (56.5%) when compared to Cashew nuts (4.7% and 45.5%, respectively). Similar content (≈37.0%) of oleic and linoleic fatty acids was displayed by Brazil nuts, in contrast to Cashew nuts, which showed 64.9% of oleic and 17.5% of linoleic fatty acids. Sodium caseinate solution displayed higher instability index, which was significantly reduced when using gelatin. Coating thickness (20 μm) of the nuts was evaluated by scanning electron microscopy analysis. A lower transmission rate of oxygen was observed in blended films with Boldo extract. Lastly, due to the oxygen barrier effect and the addition of Boldo extract, the coatings protected Brazil and Cashew nuts against oxidation, when compared with the unprotected samples, during 120 days of storage.     

澳洲坚果各部位蜀黍苷含量的测定

为检测澳洲坚果果仁、花、叶、壳和青皮各部位的蜀黍苷含量,并为澳洲坚果各部位的开发利用提供依据,以苦杏仁苷为内标物质,采用高效液相色谱法,Diamonsil C₁₈(150 mm×4.6 mm,5 μm)色谱柱,柱温35℃,自动进样器进样量5 μL,总流速1.0 mL/min,乙腈(A)-0.1%甲酸水溶液(B)为流动相,使用蒸发光散射检测器(ELSD)进行检测。结果表明:蜀黍苷和苦杏仁苷标准品的浓度比(X)与对应的峰面积比(Y)所作标准曲线方程为Y=0.465389X2+0.349685X-0.000520968,决定系数R2=0.9977,RSD为2.60%。方法的平均回收率为97.93%±2.35%,RSD为2.39%。对澳洲坚果各部位蜀黍苷含量进行测定发现,澳洲坚果花中蜀黍苷含量最高,达(49.92±0.96)mg/g,叶次之,果仁中蜀黍苷含量最低,仅为(0.64±0.01)mg/g。且不同品种青皮中蜀黍苷含量亦不同。HPLC-ELSD内标法测定蜀黍苷快速简便,准确度高,重复性好,成本较低,测定结果可靠。澳洲坚果花、叶中蜀黍苷含量较高,使用时应适当考虑脱除其中的蜀黍苷。澳洲坚果仁中仅含微量蜀黍苷,在安全使用范围之内。