Micromechanical properties of almond kernels with various moisture content levels

Almond fruits are subjected to various mechanical stresses throughout production, from harvest to processing, storage and packaging. Kernel properties play an important role in reducing mechanical damage such as scratches and penetration of shell pieces. Knowledge of kernel properties under various conditions of the fruit can assist in optimising post-harvest and processing lines to minimise kernel damage and thus maximise final kernel quality. Kernel moisture content is one of the main attributes affecting the kernel’s response to mechanical processing. Increasing the kernel moisture content to an optimum level through wetting fruit prior to processing can lead to a reduced percentage of damaged kernel. Water added to the structure of kernels acted as a plasticiser and helped the kernels to absorb the mechanical load instead of fracturing and breaking into pieces. In this study, tests were conducted on almond kernels with different moisture content levels from 5.52 to 14.09g/100g wet basis. Kernels from a Nonpareil variety were tested in dried and wetted conditions. Test results showed that kernels with higher moisture content were able to undergo a larger deformation at a given force value in comparison with dry kernels. Average deformation for dry samples was from 0.12 mm, which increased to an average of 0.25 mm in wetted samples. The effect of skin on the mechanical properties of the kernels (with and without skin) was studied using a mechanical tester. The test results showed a peak force value in samples tested with skin in comparison with the kernels tested without skin.     

Dietary fibre and components of the nitrogen-free extract of almond kernels

Determinations of neutral and acid detergent fibre residues (NDF and ADF), hemicellulose, cellulose and lignin in almond nuts (Prunus amygdalus) were carried out. The NDF content was about 5% while the crude fibre content was only approximately 2%. The composition of several components of nitrogen-free extract (NFE) such as soluble sugars, starch, gums and mucilages and pectins were also determined, and the results are discussed.     

Stack ensembled model to measure size and mass of almond kernels

After harvesting almond crop, accurate measurement of almond kernel sizes is a significant specification to plan, develop and enhance almond processing operations. The size and mass of the individual almond kernels are vital parameters usually associated with almond quality and yield. In this study, we propose a novel methodology that combines image processing and machine-learning ensemble that accurately measures the size and mass of whole raw almond kernels (classification—Nonpareil) simultaneously. We have developed an image-processing algorithm using recursive method to identify the individual almond kernels from an image and estimate the size of the kernels based on the occupied pixels by a kernel. The number of pixels representing an almond kernel was used as its digital fingerprint to predict its size and mass. Various popular machine learning (ML) models were implemented to build a stacked ensemble model (SEM), predicting the mass of the individual almond kernels based on the features derived from the pixels of the individual kernels in the image. The prediction accuracy and robustness of image processing and SEM were analyzed using uncertainty quantification. The mean error in estimating the average length of 1,000 almond kernel was 3.12%. Similarly, mean errors associated with predicting the 1,000 kernel mass were 0.63%. The developed algorithm in almond imaging in this study can be used to facilitate a rapid almond yield and quality appraisals.     

Reduction of Salmonella enteritidis population sizes on almond kernels with infrared heat

Catalytic infrared (IR) heating was investigated to determine its effect on Salmonella enterica serovar Enteritidis population sizes on raw almond kernels. Using a double-sided catalytic IR heating system, a radiation intensity of 5,458 W/m2 caused a fast temperature increase at the kernel surface and minimal temperature differences between the top and bottom kernel surfaces. Exposure of dry kernels to IR heat for 30, 35 and 45 s resulted in maximum kernel surface temperatures of 90, 102, and 113 degrees C, and when followed by immediate cooling at room temperature, yielded a 0.63-, 1.03-, and 1.51-log reduction in S. enterica population sizes, respectively. The most efficacious decontamination treatment consisted of IR exposure, followed by holding of the kernels at warm temperature for 60 min, which effected a greater than 7.5-log reduction in S. enterica on the kernels. During that treatment, the kernel surface temperature rose to 109 degrees C and gradually decreased to 80 degrees C. Similar IR and holding treatments with lower maximum kernel surface temperatures of 104 and 100 degrees C yielded reductions of 5.3 and 4.2 log CFU/g kernel, respectively. During these treatments, moisture loss from the kernels was minimal and did not exceed 1.06%. Macroscopic observations suggested that kernel quality was not compromised by the IR-holding combination treatment, as skin morphology, meat texture, and kernel color were indistinguishable from those of untreated kernels. Our studies indicate that IR heating technology is an effective dry pasteurization for raw almonds.     

Survival of Salmonella Enteritidis PT 30 on inoculated almond kernels in hot water treatments

Almonds are blanched by exposure to hot water or steam-injected water to remove the pellicle (skin) from the kernel. This study evaluated the survival of Salmonella Enteritidis PT 30, Salmonella Senftenberg 775W and Enterococcus faecalis on whole raw almond kernels exposed to hot water. Whole, inoculated (7 to 9 log CFU/g) Nonpareil almonds (40 g) were submerged in 25 L of water maintained at 60, 70, 80 and 88 °C. Almonds were heated for up to 12 min, drained for 2 s, and transferred to 80 mL of cold (4 °C) tryptic soy broth. Almonds in broth were stomached at high speed for 2 min, serially diluted, plated onto tryptic soy and bismuth sulfite agars (Salmonella) or bile esculin agar (Enterococcus) and incubated at 37 °C for 24 and 48 h, respectively. D values of 2.6, 1.2, 0.75 and 0.39 min were calculated for exposure of S. Enteritidis PT 30 to water at 60, 70, 80 and 88 °C, respectively; the calculated z value was 35 C°. D values determined for Salmonella Senftenberg 775W and E. faecalis at 88 °C were 0.37 and 0.36 min, respectively. Neither Salmonella serovar could be recovered by enrichment of 1-g samples after almonds inoculated at 5 log CFU/g were heated at 88 °C for 2 min. These data will be useful to validate almond industry blanching processes.     

Compositional changes and biosynthesis of lipids in the developing kernels of almond (Prunus amygdalus batsch)

Fruit and kernel weights of developing almond kernels increased with age. The kernel contents had a translucent and jelly-like appearance in the initial developmental stages, but solidified prior to the accumulation of dry matter, mainly oil, from 50 days after fertilisation (DAF). During kernel development the oil content displayed a double sigmoid pattern. Oleic and linoleic acids accumulated to similar levels, but the linolenic acid content decreased during development. Oil-filling ([1-¹⁴C]acetate incorporation) commenced at 50 DAF, and reached a maximum level at 70 DAF. The total polar lipid content was highest at 10 DAF, as determined by radioactive labelling, but from 30 DAF onwards a de-novo synthesis was noted. Diphosphatidyl glycerol (Cardiolipin) acted as a temporary reservoir for the synthesis of phospholipids from 70 DAF, and thereafter the synthesis of phosphatidyl choline was enhanced. In the initial stages, the rate of synthesis of monogalactosyl diglycerides was greater than that of digalactosyl diglycerides, and a de-novo synthesis of both was observed from 30 DAF. The synthesis of triacylglycerols corresponded well with the pattern of oil-filling. The level of ¹⁴C radioactivity recorded in sterol esters was greater at the initial stages, but declined from 50 DAF, possibly because of the effect of dilution, as envisaged in the case of the triacylglycerols.     

Effect of γ-irradiation on the physicochemical and sensory properties of raw unpeeled almond kernels (Prunus dulcis)

The present study evaluated the quality of raw unpeeled almonds as a function of irradiation dose in order to determine dose levels causing minimal undesirable changes to almonds. Physicochemical (color, peroxide value, hexanal content, fatty acid composition, volatile compounds) and sensory (color, texture, odor, taste) properties of almonds were determined as a function of irradiation dose.Results showed a ten-fold increase in peroxide value (PV) after irradiation at a dose of 7 kGy. A small but statistically significant (p < 0.05) change was observed in hexanal concentration as a result of irradiation. No statistically significant (p > 0.05) changes were recorded in polyunsaturated fatty acids (PUFA) up to a dose of 7 kGy while monounsaturated fatty acids (MUFA) decreased manifested as a respective increase in saturated fatty acids (SFA) up to 3 kGy. Volatile compounds such as aldehydes, ketones and alcohols increased with increasing irradiation dose indicating enhanced lipid oxidation. Color parameter L^? decreased (p < 0.05) at doses > 3 kGy while color parameters a^? and b^? remained unaffected by irradiation. Sensory analysis showed that almonds remained organoleptically acceptable up to a dose of 3 kGy.Industrial Relevance: Irradiation is very efficient in controlling insects and growth of aflatogenic Aspergillus spp. in dry nuts.     

In vitro antioxidant, antimicrobial, and antitumor activities of bitter almond and sweet apricot (Prunus armeniaca L.) kernels

The aim of this study was to investigate in vitro antioxidant, antimicrobial, and antitumor activities of water, methanol, and ethanol extracts of sweet apricot and bitter almond kernels. The fruit extracts were evaluated for their antioxidant activities using various antioxidant methodologies including phosphomolybdenum assay (total antioxidant capacity), free radical scavenging assay, ferric ion reducing power, and β-carotene/linoleic acid bleaching test system. The antioxidant capacity of the sweet apricot kernels was better than those recorded for bitter almond ones. The highest total antioxidant activity (59.53 mg/g dry extract), ferric ion reducing power (1.626), antioxidant index (67%), total phenolic content (3.290 mg/g dry extract), and total lycopene content (4.70mg/mL) were detected in the aqueous extract of sweet apricot kernels. The antimicrobial activities of the above extracts were also tested against some pathogenic microorganisms using a disc-diffusion method. Additionally, the extracts of sweet apricot and bitter almond kernels could inhibit the growth of human breast (MCF-7), colon (HCT-116), and hepatocellular (Hep-G2) carcinoma cell lines in a dose-dependent manner with different sensitivity between cell lines. The overall results indicate promising baseline information for the potential uses of apricot (Prunus armeniaca L.) fruit extracts in the treatment of infectious diseases and tumors.     

杏仁香肠的研制

将杏仁加入到配料中 ,制成有特殊风味和口感的杏仁香肠。提出了杏仁香肠的制作工艺和杏仁脱苦、护色、破碎等的处理方法 ,通过试验确定了杏仁的适宜添加量 ,并指出了杏仁中的氰苷转变成有毒物质氢氰酸的条件和安全的处理方法。     

杏仁脱皮去苦及杏仁油脱色研究

采用正交实验方法研究杏仁脱皮去苦及杏仁油脱色,从中筛选出最佳工艺参数。在沸腾的pH值为9的碱液中浸泡5min杏仁脱皮效果好;在pH值为4的35℃的酸性溶液中浸泡36h,可以完全去除苦杏仁的苦味;粗制杏仁油脱色,用自制的脱色剂,油剂比20∶1,在85℃下搅拌5min后过滤可获得微黄透明的脱色杏仁油。     

Acrylamide in almond products

Acrylamide was determined in 86 different almond products, such as roasted almonds, almond-containing bakery products, raw almonds, and marzipan. The highest acrylamide concentrations were found in dark roasted almonds, while only moderate acrylamide contents were determined in bakery products. Roasting experiments under different process conditions showed that acrylamide increases with time and that temperature has a much stronger effect on acrylamide formation than time. During roasting reducing sugars are consumed faster and to a larger extent than free asparagine, suggesting that the content of reducing sugars may be a critical factor for acrylamide formation in roasted almonds. Acrylamide was found to decrease in roasted almonds during storage at room temperature.     

杏仁发酵乳制作工艺

<正> 杏仁是杏子核内的果仁,肉色洁白。杏仁分甜杏仁和苦杏仁两种,苦杏仁含氢氰酸较高,香气较为浓烈。在糖果和饮料中作为配料使用时,一般以甜杏仁为主,搭配一部分苦杏仁,可得到较好的香味。     

酶法制备巴旦杏蛋白工艺研究

以新疆巴旦杏为原料,采用酶法制备巴旦杏蛋白,通过比较纤维素酶、中性蛋白酶、酸性蛋白酶对巴旦杏蛋白的提取率,确定了最佳的酶为中性蛋白酶,同时考察了加酶量、料水比、时间、温度、pH等因素对巴旦杏蛋白提取率的影响。结果表明:中性蛋白酶提取巴旦杏蛋白的最佳工艺是:加酶量5%、料水比1:35、时间75min、温度50℃、pH为7.25。     

杏仁融化干酪的加工工艺研究

研究了在新鲜牛乳中加入细碎杏仁生产一种融化干酪的加工工艺,同时对其焙烤特性进行了评价.实验证实,当加入2%杏仁时,干酪的焙烤特性最佳.     

杏汁澄清方法的筛选研究

就几种常见的果汁澄清方法在杏汁上的应用进行了筛选研究,结果表明,杏汁澄清中果胶酶澄清效果好,成本低,操作简单,且无二次沉淀,其最佳组合为pH4,酶用量0.01‰,时间40min,温度45℃;蜂蜜虽有一定的澄清效果,但会出现二次沉淀,在实际应用中成本也较高;海藻酸钠-碳酸钠法、单宁-明胶法澄清效果差,操作繁杂。     

杏仁豆腐的加工工艺

杏仁为蔷薇科植物杏、山杏、野杏、东北杏的种子。栽培所产杏仁甜的较多,野生的一般味较苦。据《本草纲目》记载,其味甘、苦、性冷利、有小毒;其主要成分为蛋白质25%、脂肪30%～50%、碳水化合物8%～9%、纤维素8%、苦杏仁苷2%～4%,此外还含有丰富的钙、磷、硒。杏仁可药食兼用,随着现代医学发展,杏仁的其他生理功能如抗肿瘤、降血糖、抗炎、镇痛作用渐渐得到人们的证实,成为人们经常选择的保健食品之一。但由于以杏仁为原料的食品较少,且多为各种小吃,本文谈及以苦杏仁为原料,研制了一种新型豆腐制品,为杏仁的加工制造提供了另一条思路。一、…     

杏仁山楂发酵果酒的工艺优化研究

杏仁具有很好的营养和保健作用,本研究以杏仁为主料、山楂为辅料、红曲作为发酵剂进行杏仁果酒发酵研究,通过试验得出杏仁山楂果酒最佳工艺为主发酵时间7d,初始pH值为4.5,酵母菌接种量为7%,在26℃后发酵后陈酿,澄清过滤后得到酒精度在8.5%vol左右的保健型杏仁山楂果酒。     

苦杏仁蛋白质功能特性的研究

目的研究苦杏仁蛋白加工特性,为其应用提供理论依据。方法采用单因素变量法测定p H值、温度、氯化钠浓度、蛋白质浓度等因素对杏仁蛋白加工特性的影响。结果在蛋白等电点附近时,杏仁蛋白的持水性、起泡性、乳化性及乳化稳定性均最差;在25~35℃范围内,提高温度可促进杏仁蛋白各项功能特性的提高,但超出55℃后,各项功能特性降低;低浓度的氯化钠可促进蛋白质起泡性及泡沫稳定性、乳化性及乳化稳定性的提高,高浓度氯化钠(0.8 mol/L)对蛋白功能特性提高具有抑制作用;蛋白质的起泡性及泡沫稳定性、乳化性及乳化稳定性随其浓度增加略有升高。结论 p H值、温度、氯化钠浓度、蛋白质浓度等因素对蛋白特性影响显著,在将杏仁蛋白应用于食品中时应考虑这些因素的影响。